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Week 4 Flashcards

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1
Q

Defining Fungi

A

Mycologists believe there may be as many as 1.5 million fungal species​

Single-celled or multicellular​

Sexual or asexual​

Exhibit an unusual form of mitosis​

Specialized to extract and absorb nutrients from surroundings​

Animal and fungi last shared a common ancestor 460 M Y A

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2
Q

Mycologists agreed on 6 major monophyletic phyla

A

Blastocladiomycota​

Neocallismastigomycota​

Chytridiomycota​

Glomeromycota​

Basidiomycota​

Ascomycota​

(1 paraphyletic phylum​

Zygomycota​

Microsporidia are sometimes included​)

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3
Q

Chytridiomycota

A

Aquatic, flagellated fungi that produce haploid gametes by sexual reproduction or diploid zoospores by asexual reproduction.

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4
Q

Zygomycota

A

Multinucleate hyphae lack septa, except for reproductive structures; fusion of hyphae leads directly to formation of a zygote in zygosporangium, in which meiosis occurs just before it germinates; asexual reproduction is most common.

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5
Q

Glomeromycota

A

Form arbuscular mycorrhizae. Multinucleate hyphae lack septa. Reproduce asexually.

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6
Q

Ascomycota

A

In sexual reproduction, ascospores are formed inside a sac called an ascus; asexual reproduction is also common.

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7
Q

Basidiomycota

A

In sexual reproduction, basidiospores are borne on club-shaped structures called basidia; asexual reproduction occurs occasionally.

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8
Q

Neocallimastigomycota

A

Fungi lacking mitochondria that use anaerobic metabolism to grow in the guts of herbivores. Possess the ability to degrade cellulose.

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9
Q

Blastocladiomycota

A

Exhibit alternation of generations as seen in plant reproduction. Possess characteristic nuclear cap composed of membrane-bound ribosomes.

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10
Q

General features of the Fungi

A

Multicellular fungi consist of long, slender filaments called hyphae​

Some hyphae are continuous.​

Others are divided by septa.​

Cytoplasm flows throughout hyphae​

Allows rapid growth under good conditions.

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11
Q

Mycelia and Cell Walls

A

Mycelium – mass of connected hyphae​

Grows through and digests its substrate.​

Fungal cell walls include chitin​

Also found in the hard shells (exoskeletons) of arthropods.

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12
Q

Hyphae may have more than one nucleus

A

Hyphae may have more than one nucleus​

Monokaryotic – 1 nucleus.​

Dikaryotic – 2 nuclei.​

Both genomes transcribed.

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13
Q

Heterokaryotic and Homokaryotic

A

Heterokaryotic – nuclei from genetically distinct individuals.​

Homokaryotic – nuclei are genetically similar to one another.

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14
Q

Mitosis

A

Fungi have an unusual mitosis​

Cell is not relevant unit of reproduction – nucleus is.​

Nuclear envelope does not break down and re-form.​

Instead, the spindle apparatus is formed within it.​

With the exception of the chytrids, fungi lack centrioles​

Spindle plaques regulate microtubule formation during mitosis.

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15
Q

Reproduction

A

Capable of both sexual and asexual reproduction​

Sexual reproduction​

Fusion of two haploid hyphae of compatible mating types.​

In some fungi, fusion immediately results in a diploid (2n) cell.​

Others, have a dikaryotic stage (n + n) before parental nuclei form diploid nucleus.​

May form mushrooms or puffballs.

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16
Q

Spores

A

Spores are the most common means of reproduction among fungi​

May form from sexual or asexual processes.​

Most are dispersed by wind.

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17
Q

Nutrition

A

Obtain food by secreting digestive enzymes into surroundings​

Then absorb the organic molecules produced by this external digestion​

Great surface area-to-volume ratio.​

Fungi can break down cellulose and lignin​

Decompose wood.​

Some fungi are carnivorous.

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18
Q

Fungal Ecology

A

Fungi, together with bacteria, are the principal decomposers in the biosphere​

Many are difficult or impossible to culture in the lab—difficult to assess the diversity of species​

Can study environmental D N A, which reveals organisms prevent without having to culture them.​

Make materials available to other organisms​

Break down cellulose and lignin from wood.​

Release carbon, nitrogen, and phosphorus.

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19
Q

Fungi symbioses

A

Obligate symbiosis – essential for fungus survival.​

Facultative symbiosis – nonessential.

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20
Q

Interactions w/ Pathogens and Parasites

A

Pathogens harm host by causing disease.​

Parasites harm host, but do not cause disease.​

Commensal relationships benefit one partner but do not harm the other.​

Mutualistic relationships benefit both partners.

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21
Q

Endophytic fungi

A

Live in the intercellular spaces inside plants​

Some parasites, some commensals or mutualists​

Some fungi protect their hosts from herbivores by producing toxins.​

Perennial rye grass is more resistant to aphid feeding in the presence of endophytes.

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22
Q

Lichens

A

Symbiotic associations between a fungus and a photosynthetic partner​

Cyanobacteria, green algae, or sometimes both.​

Most are mutualistic (but some are parasites on the photosynthesizer)​

Ascomycetes are found in all but about 20 of the 15,000 lichen species

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23
Q

Lichen Biology

A

Fungi in lichens are unable to grow normally without their photosynthetic partners​

Fungi protect their partners from strong light and desiccation​

Lichens have invaded the harshest habitats​

Striking colors play a role in protecting photosynthetic partner​

Sensitive to pollutants

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24
Q

Mycorrhizae

A

Mutualistic relationships between fungi and plants​

Found on the roots of about 90% of all known vascular plant species​

Function as extensions of root system​

Increase soil contact and absorption.​

Two principal types​

Arbuscular mycorrhizae.​

Ectomycorrhizae.

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25
Q

Arbuscular mycorrhizae

A

By far the most common – on 80% of plant species​

Fungal partners are glomeromycetes​

No aboveground fruiting structures​

Potentially capable of increasing crop yields with lower phosphate and energy inputs​

Hyphae penetrate the root cell wall but not cell membranes

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26
Q

Ectomycorrhizae

A

Most hosts are forest trees (pines, oaks)​

Hosts are important carbon sinks​

Fungal partners are mostly basidiomycetes​

At least 5000 species of fungi are involved in ectomycorrhizal relationships​

Hyphae surround but do not penetrate the root cells​

Extract nitrogen and other nutrients from soil and pass them to the host

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27
Q

Animal mutual symbioses

A

Ruminant animals host neocallimastigomycete fungi in their gut​

Leaf-cutter ants have domesticated basidiomycete fungi which they keep in underground gardens​

Ants provide fungi with leaves.​

Fungi are food for the ants.

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28
Q

Fungal Parasites and Pathogens

A

Cause health issues in humans:​

Allergens trigger immune responses.​

Fungal spores cause allergic reactions but also can cause illness when in high numbers.​

Mycoses, direct infections (skin and nails).​

Ingested toxins produced by fungi.

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29
Q

Fungal toxins

A

Fungi may secrete mycotoxins making food unpalatable, carcinogenic, or poisonous​

Aspergillus flavus – aflatoxin.​

Ustilago maydis – corn smut, harms plants but not animals that eat the plants.

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30
Q

Diseases Caused by Fungi

A

Fungal diseases are difficult to treat because of the close phylogenetic relationship between fungi and animals

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31
Q

Batrachochytrium dendrobatidis causes chytridiomycosis

A

Associated with the worldwide decline in amphibian populations

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32
Q

Basidiomycota

A

Basidiomycetes are some of the most familiar fungi​

Include mushrooms, toadstools, puffballs, shelf fungi, etc.​

Also important plant pathogens like rusts and smuts.​

“Club fungi” named for basidium – club-shaped sexual reproductive structure

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33
Q

Basidiomycota Reproduction

A

Karyogamy occurs within basidia​

Only diploid cell in life cycle.​

Meiosis follows​

The four haploid products are incorporated into basidiospores

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34
Q

Basidiomycota Development

A

Spore germination leads to the production of monokaryotic hyphae​

Results in a monokaryotic mycelium, or primary mycelium.​

Different mating types of monokaryotic hyphae may fuse​

Results in a dikaryotic mycelium, or secondary mycelium.​

Heterokaryotic mycelium.​

Basidiocarps (mushrooms) are formed entirely of secondary mycelium.

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35
Q

Ascomycota

A

Contain about 75% of the known fungi​

Includes bread yeasts, common molds, cup fungi, truffles, and morels​

Serious plant pathogens – cause of chestnut blight and Dutch elm disease​

Penicillin-producing fungi are in the genus Penicillium​

“Sac fungi”, named for ascus – microscopic, saclike reproductive structure

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36
Q

Reproduction in the Ascomycota

A

Karyogamy occurs within asci​

Only diploid nucleus of life cycle.​

Asci differentiate in ascocarp​

Meiosis and mitosis follow, producing 8 haploid nuclei that become walled ascospores

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37
Q

Asexual Reproduction in the Ascomycota

A

Asexual reproduction is very common​

Conidia formed at the ends of modified hyphae called conidiophores.​

Easily dispersed, so allow for the rapid colonization of a new food source.​

Hyphae are divided by perforated septa.​

Allows cytoplasm to flow along the length of the hypha.​

Later perforations may become blocked.

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38
Q

Yeast

A

Single-celled ascomycetes​

Most reproduce asexually by cell fission or budding​

Yeasts can ferment carbohydrates​

Break down glucose into ethanol and CO2.​

Used to make bread, beer, and wine.​

Saccharomyces cerevisiae.

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39
Q

Yeast as a Model in Genetic Research

A

Yeast is a long-standing model system for genetic research​

First eukaryotes to be genetically engineered extensively.​

Saccharomyces cerevisiae first eukaryote to have genome sequenced in 1996.​

Coccidioides species can cause disease​

Endemic in soil of S W U S A.​

Cause coccidioidomycosis (Valley Fever).

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40
Q

Glomeromycota

A

Glomeromycetes are a tiny group of fungi​

Form intracellular associations with plant roots called arbuscular mycorrhizae​

Cannot survive in absence of host plant.​

Probably key for plant colonization of land​

No evidence of sexual reproduction

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41
Q

Zygomycota

A

Zygomycetes are incredibly diverse​

Not monophyletic – still under research​

Include the common bread molds​

A few human pathogens

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42
Q

Zygomycota Reproduction

A

Sexual reproduction​

Fusion of gametangia – plasmogamy.​

Haploid nuclei fuse to form diploid zygote nuclei – karyogamy.​

Develops into zygosporangium in which zygospore develops.​

Meiosis occurs during germination of zygospore.​

Releases haploid spores.​

Asexual reproduction more common​

Sporangiophores have sporangia that release spores.

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43
Q

Chytridiomycota

A

Chytridiomycetes or chytrids​

Aquatic, flagellated fungi​

Closely related to ancestral fungi​

Have motile zoospores​

Batrachochytrium dendrobatidis has been implicated in amphibian die-offs

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44
Q

Blastocladiomycetes

A

Aquatic and terrestrial​

Parasites of plants, animals, algae and fungi​

Uniflagellated zoospores​

Allomyces example​

Water mold.​

Haplodiplontic life cycle – Alternation of haploid and diploid generations in multicellular forms

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45
Q

Neocallimastigomycota

A

Digest plant biomass in mammalian herbivore rumens​

Sheep, cows, kangaroos, elephants​

Mammal depends on fungi for sufficient calories.​

Greatly reduced mitochondria lack cristae​

Zoospores have multiple flagella​

Horizontal gene transfer brought cellulase gene from bacteria into Neocallimastix genome​

Might be useful for biofuel production

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46
Q

Microsporidia

A

Unclear how they should be classified​

Tiny, obligate, intracellular, animal parasites​

Tiny genomes too​

Long thought to be protists​

Lack mitochondria​

Do not undergo aerobic respiration.​

Need their host for A T P

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47
Q

Encephalitozoon cuniculi

A

Commonly cause disease in immunosuppressed patients​

Infect hosts with their spores, which contain a polar tube​

Infects intestinal and neuronal cells, leading to diarrhea and neurodegenerative disease

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48
Q

Heterotrophy

A

obtain energy and organic molecules by ingesting other organisms

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49
Q

Active movement

A

Move more rapidly and in more complex ways

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50
Q

Diversity of form

A

Vary greatly in form, ranging in size from organisms too small to see with the unaided eye to enormous

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51
Q

Diversity of habitat

A

Grouped into 35 to 40 phyla, most that occur only in the sea but many occur in fresh water and on land

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52
Q

Sexual reproduction

A

Most animals reproduce sexually. Animal eggs, which are nonmobile

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53
Q

Embryonic development

A

Zygote first undergoes a series of mitotic divisions that produces a ball of cells

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54
Q

Tissues

A

Cells of most animals are organized into structural and functional units called tissues

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55
Q

No cell walls

A

They lack rigid cell walls and are usually flexible

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56
Q

Five key innovations can be noted in animal evolution

A

Symmetry​

Tissues​

Body cavity​

Various patterns of embryonic development​

Segmentation, or repeated body units

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57
Q

Evolution of symmetry

A

Sponges also lack any definite symmetry.​

Virtually all other animals have a symmetry defined along an imaginary axis drawn through the animal’s body.​

There are two main types of symmetry

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58
Q

There are two main types of symmetry

A

Radial symmetry​

Body parts arranged around central axis.​

Can be divided into two equal halves by any plane that passes through the center.​

Bilateral symmetry​

Body has right and left halves that are mirror images.​

Only the sagittal plane bisects the animal into two equal halves.

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59
Q

Bilaterally symmetrical animals have two main advantages over radially symmetrical ones

A

Cephalization​

Evolution of a definite brain area.​

Directional movement

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60
Q

Evolution of tissues

A

Zygotes (fertilized eggs) are totipotent.​

Can give rise to all other body cells.​

As the embryo develops, cells specialize.​

This process is irreversible, except in sponges.​

In sponges – the simplest animals– defined tissues and organs are not present.​

Have the ability to disaggregate and aggregate their cells.​

All other animals have distinct and well-defined tissues.​

Have irreversible differentiation for most cell types.

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61
Q

Evolution of a body cavity

A

Most animals have embryos that produce three germ layers, which makes them triploblastic.​

Outer ectoderm (body coverings and nervous system).​

Middle mesoderm (skeleton and muscles).​

Inner endoderm (digestive organs and intestines). ​

All triploblastic animals have bilateral symmetry.​

Cnidarians are diploblastic.​

Have an endoderm and an ectoderm.​

Sponges lack germ layers.

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62
Q

Body cavity

A

Space surrounded by mesoderm tissue that is formed during development

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63
Q

Three basic kinds of body plans​

A

Acoelomates = No body cavity.​

Pseudocoelomates = Body cavity between mesoderm and endoderm.​

Called the pseudocoelom.​

Coelomates = Body cavity entirely within the mesoderm.​

Called the coelom.

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64
Q

Circulatory Systems

A

The body cavity made possible the development of advanced organ systems​

Coelomates developed a circulatory system to flow nutrients and remove wastes​

Open circulatory system: blood passes from vessels into sinuses, mixes with body fluids, and reenters the vessels​

Closed circulatory system: blood moves continuously through vessels that are separated from body fluids​

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65
Q

Evolution of different patterns of development

A

The basic Bilaterian pattern of development:​

Mitotic cell divisions (called cleavage) of the egg form a hollow ball of cells, called the blastula.​

Blastula indents to form a two-layer- thick ball with:​

Blastopore = Opening to outside.​

Archenteron = Primitive body cavity.

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66
Q

Bilaterians can be divided into two groups:​

A

Protostomes develop the mouth first from or near the blastopore.​

Anus (if present) develops either from blastopore or another region of embryo.​

Deuterostomes develop the anus first from the blastopore.​

Mouth develops later from another region of the embryo.

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67
Q

Cleavage pattern of embryonic cells

A

Protostomes = Spiral cleavage.​

New cells form to the right or left of previous cells.​

Deuterostomes = Radial cleavage.​

New cells form on top of previous cells.

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68
Q

Developmental fate of cells

A

Protostomes = Determinate development.​

Cell fate is determined early.​

Deuterostomes = Indeterminate development.​

Cell fate is not determined until after several divisions.

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69
Q

Formation of the coelom​

A

Protostomes—cells move apart to form coelom.​

Deuterostomes—groups of cells pouch off to form coelom.

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70
Q

Evolution of segmentation

A

Segmentation provides two advantages.​

Allows redundant organ systems in adults such as occurs in the annelids​

Allows for more efficient and flexible movement because each segment can move independently​

Segmentation appeared several times in the evolution of animals

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71
Q

Anatomy and embryology have been used previously to infer phylogeny

A

In the past 30 years, sequence data have accumulated​

May suggest different phylogenetic relationships.​

Has resolved some problematic issues with previous phylogeny.

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72
Q

Although they do have differences, traditional animal phylogeny shares common ground with new phylogenies

A

Traditional animal phylogeny was developed from morphological, molecular, life history, and other types of relevant data.​

New phylogenies are constructed from molecular data.​

Some parts of this phylogeny are not firmly established.​

New studies are constantly appearing, often with somewhat different conclusions.

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73
Q

Animals are divided into two main branches:

A

Sponges: monophyletic.​

Eumetazoa = Animals other than sponges.​

Cnidaria—branch off evolutionary tree before bilateria.​

Bilateria.​

Phylogeny of deuterostomes has not changed much.​

Phylogeny of protostomes has changed due to molecular data.

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74
Q

Arthropoda​

(arthropods)

A

Chitinous exoskeleton covers segmented, coelomate body. With paired, jointed appendages; many types of insects have wings. Occupy marine, terrestrial, and freshwater habitats. Most arthropods are insects (as are most animals!).

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75
Q

Mollusca​

(mollusks)

A

Coelomate body of many mollusks is covered by one or more shells secreted by a part of the body termed the mantle. Many kinds possess a unique rasping tongue, a radula. Members occupy marine, terrestrial, and freshwater habitats.

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76
Q

Chordata​

(chordates)

A

Each coelomate individual possesses a notochord, a dorsal nerve cord, pharyngeal slits, and a postanal tail at some stage of life. In vertebrates, the notochord is replaced during development by the spinal column. Members occupy marine, terrestrial, and freshwater habitats.

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77
Q

Platyhelminthes​

(flatworms)

A

Unsegmented, acoelomate, bilaterally symmetrical worms. Digestive cavity has only one opening; tapeworms lack a gut. Many species are parasites of medical and veterinary importance. Members occupy marine, terrestrial, and freshwater habitats (as well as the bodies of other animals).

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78
Q

Nematoda (roundworms)

A

Pseudocoelomate, unsegmented, bilaterally symmetrical worms; tubular digestive tract has mouth and anus. Members occupy marine, terrestrial, and freshwater habitats; some are important parasites of plants and animals, including humans.

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79
Q

Annelida​

(segmented worms)

A

Segmented, bilaterally symmetrical, coelomate worms with a complete digestive tract; most have bristles (chaetae) on each segment that anchor them in tubes or aid in crawling. Occupy marine, terrestrial, and freshwater habitats.

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80
Q

Porifera​

(sponges)

A

Bodies of most asymmetrical: defining “an individual” is difficult. Lacking tissues or organs, the body is a meshwork of cells surrounding channels that open to the outside through pores and expand into internal cavities lined with food-filtering flagellated cells (choanocytes). Most species are marine (150 species live in freshwater).

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81
Q

Echinodermata​

(echinoderms)

A

Adult body pentaradial (fivefold) in symmetry. Water-vascular system​

is a coelomic space; endoskeleton of calcium carbonate plates. Many can regenerate lost body parts. Fossils are more diverse in body plan than extant species. Exclusively marine.

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82
Q

Cnidaria​

(cnidarians)

A

Radially symmetrical, acoelomate body has tissues but no organs. Mouth opens into a simple digestive sac and is surrounded by tentacles armed with stinging capsules (nematocysts). In some groups, individuals are joined into colonies; some can secrete a hard exoskeleton. The very few nonmarine species live in freshwater.

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83
Q

Cnidaria​

(cnidarians)

A

Radially symmetrical, acoelomate body has tissues but no organs. Mouth opens into a simple digestive sac and is surrounded by tentacles armed with stinging capsules (nematocysts). In some groups, individuals are joined into colonies; some can secrete a hard exoskeleton. The very few nonmarine species live in freshwater.

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84
Q

Bryozoa (moss animals) (also called Polyzoa and Ectoprocta)

A

The only exclusively colonial phylum; each colony comprises numerous small, coelomate individuals (zooids) connected by an exoskeleton (calcareous in marine species, organic in most freshwater ones). A ring of ciliated tentacles (lophophore) surrounds the mouth of each zooid; the anus lies beyond the lophophore.

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85
Q

Rotifera (wheel animals)

A

Small pseudocoelomates with a complete digestive tract including a set of complex jaws. Cilia at the anterior end beat so they resemble a revolving wheel. Some are very important in marine and freshwater habitats as food for predators such as fishes.

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86
Q

Nemertea (ribbon worms) (also called Rhynchocoela)

A

Protostome worms notable for their fragility—when disturbed, they fragment into pieces. Long, extensible proboscis occupies their coelom; that of some tipped by a spearlike stylet. Most marine, but some live in freshwater, and a few are terrestrial.

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87
Q

Tardigrada (water bears)

A

Microscopic protostomes with five body segments and four pairs of clawed legs. An individual lives a week or less but can enter a state of suspended animation (“cryptobiosis”) in which it can survive for many decades. Occupy marine, freshwater, and terrestrial habitats.

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88
Q

Brachiopoda​

(lamp shells)

A

Protostomous animals encased in two shells that are oriented with respect to the body differently than in bivalved mollusks. A ring of ciliated tentacles (lophophore) surrounds the mouth. More than 30,000 fossil species are known.

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89
Q

Ctenophora​

(sea walnuts)

A

Gelatinous, almost transparent, often bioluminescent marine animals; eight bands of cilia; largest animals that use cilia for locomotion; complete digestive tract with anal pore.

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90
Q

Chaetognatha​

(arrow worms)

A

Small, bilaterally symmetrical, transparent marine worms with a fin along each side, powerful bristly jaws, and lateral nerve cords. Some inject toxin into prey and some have large eyes. It is uncertain if they are coelomates, and, if so, whether protostomes or deuterostomes.

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91
Q

Onychophora​

(velvet worms)

A

Segmented protostomous worms with a chitinous soft exoskeleton and unsegmented appendages. Related to arthropods. The only exclusively terrestrial phylum, but what are interpreted as their Cambrian ancestors were marine.

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92
Q

Loricifera​

(loriciferans)

A

Tiny marine pseudocoelomates that live in spaces between grains of sand. The mouth is borne on the tip of a flexible tube. Discovered in 1983.

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93
Q

Cycliophora (cycliophorans)

A

Microscopic animals that live on mouthparts of claw lobsters. Discovered in 1995.

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94
Q

Placozoa

A

Simple animals with only a few cell types and a few thousand cells. Flat with irregular body outline; these marine animals are only 1 mm in diameter. Their biology is not well-known.

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95
Q

Micrognathozoa (micrognathozoans)

A

Microscopic animals with complicated jaws. Discovered in 2000 in Greenland.

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96
Q

Protostomes are divided into

A

Lophotrochozoans​

Grow by gradual addition to the body mass.​

Have spiral cleavage.​

Ecdysozoans​

Animals that molt.​

Includes the arthropods and many other phyla.

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97
Q

Deuterostomes include chordates and echinoderms

A

They consist of fewer phyla and species than protostomes.​

They are more uniform in many ways, despite great differences.

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98
Q

Kingdom Animalia (the Metazoa) is divided into two branches:

A

Parazoa: Animals lacking tissues (and therefore organs) and a definite symmetry​

Phylum Porifera.​

Eumetazoa: Animals with a definite shape and symmetry, tissues, and possibly organs and organ systems

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99
Q

Phylum Porifera

A

Sponges​

26,000 marine species; 150 freshwater species​

Among the most abundant animals in the deep ocean

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100
Q

Sponge Characteristics

A

Most members lack symmetry​

Various growth forms​

Larval sponges free-swimming.​

Adults remain attached – sessile.​

Cell types​

Truly multicellular.​

3 functional layers in vase-shaped body.

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101
Q

Functional Layers of the Body Wall

A

Outer epithelium​

Made up of flattened cells.​

Water comes in ostia, exits through osculum.​

Mesohyl​

Middle layer – gelatinous matrix.​

Spicules – needles of calcium carbonate.​

Spongin – reinforcing tough protein fibers.​

Lining of the internal cavity​

Choanocytes.​

Collar cells.​

Flagellated – contributes to water circulation.​

Face internal cavity.​

Engulf and digest food from passing water.

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102
Q

Sponge Reproduction

A

Asexual​

Fragmentation.​

Sexual​

Choanocytes transform into sperm.​

Sperm captured and passed to egg cell in mesohyl.​

Development may occur within mother or in open water.​

Larva is planktonic; will settle and transform into adult.

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103
Q

Eumetazoa

A

Animals with true tissues​

Embryos have distinct layers​

Inner endoderm forms the gastrodermis (digestive tissue).​

Outer ectoderm forms the epidermis and nervous system.​

Middle mesoderm (only in bilateral animals) forms the muscles.​

True body symmetry​

Radial symmetry.​

Bilateral symmetry.

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104
Q

Phylum Ctenophora​

A

Known as comb jellies, sea walnuts, or sea gooseberries​

8 rows of comblike plates of fused cilia that beat in a coordinated fashion​

Many bioluminescent​

2 tentacles covered with colloblasts​

Discharge strong adhesive used to capture prey.​

Phylogenetic position unclear

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105
Q

Phylum Cnidaria

A

Most marine, few fresh water species​

Diploblastic​

Bodies have distinct tissues but no organs​

No reproductive, circulatory, or excretory systems.​

No concentrated nervous system​

Latticework of nerve cells.​

Touch, gravity, light receptors.​

Capture prey with nematocysts​

Unique to this phylum.

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106
Q

2 Basic Body Forms

A

Polyps – cylindrical and sessile​

Medusa – umbrella-shaped and free-living

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107
Q

Body plan has single opening leading to gastrovascular cavity

A

Site of digestion.​

Most gas exchange.​

Waste discharge.​

Formation of gametes in many.​

2 layers to body wall​

Epidermis.​

Gastrodermis.​

Mesoglea occurs between layers.

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108
Q

Gastrovascular space also serves as hydrostatic skeleton

A

Provides a rigid structure against which muscles can operate.​

Gives the animal shape.​

Many polyp species build an exoskeleton of chitin or calcium carbonate around themselves​

Some build an internal skeleton.

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109
Q

Cnidarian Life Cycle

A

Some cnidarians occur only as polyps, and others exist only as medusae, but many alternate between these two phases​

Both phases consist of diploid individuals.​

In general, in species having both polyp and medusa in the life cycle, the medusa forms gametes​

Sexes separate.​

Gonochorism – individual is either male or female.​

Zygote develops into planktonic planula.​

Metamorphosis into polyp.​

Polyp produces medusae or other polyps asexually.

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110
Q

Digestion

A

Major evolutionary innovation in cnidarians is extracellular digestion of food inside the animal​

Digestion takes place partly in gastrovascular cavity.​

Cells then engulf fragments by phagocytosis.

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111
Q

Nematocysts

A

Cnidarians use nematocysts to capture prey​

Secreted within nematocyte.​

Mechanism of discharge unknown.​

Some carry venom.

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112
Q

5 Cnidarian Classes

A

Anthozoa

Cubozoa​

Hydrozoa

Scyphozoa

Staurozoa

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113
Q

The Bilaterian Acoelomates

A

Characterized by bilateral symmetry​

Allowed for high levels of specialization​

Divided into 2 clades​

Protostomes and Deuterostomes.​

Acoel flatworms.

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114
Q

Phylum Acoela

A

Acoel flatworms were once considered basal members of the phylum Platyhelminthes​

Have a primitive nervous system and lack a digestive cavity​

Based on molecular evidence, similarities are convergent

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115
Q

Lophotrochozoa

A

Embryos develop using spiral cleavage​

Most live in water​

Move using cilia or contractions of the body musculature

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116
Q

Defining Characteristics of the Lophotrochozoa​

A

Two characteristics define members of this group​

Trochophore—a free-living larva.​

Lophophore—a horseshoe-shaped crown of ciliated tentacles surrounds the mouth used in filter-feeding.

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117
Q

Ecdysozoa

A

Contains animals that molt​

Exoskeleton.​

Hard external skeleton.​

Two large groups​

Arthropods.​

Nematodes.

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118
Q

Flatworms (Platyhelminthes)

A

Simple bodies with no circulatory or respiratory systems, but complex reproductive system​

Includes marine and freshwater planarians and parasitic flukes and tapeworms

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119
Q

Flatworms

A

Flatworms are ciliated, soft-bodied animals​

Bodies are solid aside from an incomplete digestive cavity​

Many species are parasitic​

Others are free-living​

Marine, freshwater, moist terrestrial

Only one opening to digestive cavity

Lack circulatory system

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120
Q

Excretion and Osmoregulation

A

Have an excretory and osmoregulatory system​

Network of fine tubules runs through body.​

Flame cells located on the side branches.​

Flagella move water and excretory substances into the tubules and then to pores located between the epidermal cells through which the liquid is expelled.​

Metabolic wastes are excreted into the gut and eliminated through the mouth.

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121
Q

Nervous System and Reproduction

A

Simple nervous system​

Anterior cerebral ganglion and nerve cords.​

Eyespot can distinguish light from dark.​

Reproduction​

Most are hermaphroditic.​

Undergo sexual reproduction.​

Also have capacity for asexual regeneration.

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122
Q

Major Groups of Flatworms

A

Subphylum Neodermata.​

Includes the parasitic flatworms​

Two subgroups​

Trematoda​

Cercomeromorpha

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123
Q

Trematoda

A

Trematoda – flukes.​

Attach within host body by suckers, anchors, or hooks.​

Life cycle may have 2 or more hosts.​

Includes the miracidium, sporocyst, redia, and cercaria stages.​

Clonorchis sinensis, oriental liver fluke.​

Schistosoma.

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124
Q

Schistosoma

A

One of most important trematodes to human health are blood flukes Schistosoma​

Afflict 200 million people in tropical Asia, Africa, Latin America, and the Middle East.​

About 200,000 people die each year from schistosomiasis or bilharzia.​

Fertilized egg must break through the wall of the blood vessels in intestine or the urinary bladder to get out.

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125
Q

Tapeworms

A

Most of tapeworm body is proglottids​

Complete hermaphroditic unit, containing both male and female reproductive organs.​

Formed continuously.​

Beef tapeworm, Taenia saginata​

Frequent human parasite.​

From eating uninspected rare beef.

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126
Q

Phylum Rotifera

A

Bilaterally symmetrical, unsegmented pseudocoelomates​

Highly developed internal organs​

Corona – “wheel animals”​

Conspicuous ring of cilia at anterior end.​

Used for locomotion and sweeping food into the mouth.

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127
Q

Phylum Mollusca

A

Second in diversity only to arthropods​

Include snails, slugs, clams, octopuses and others​

Some have a shell, some do not

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128
Q

Features of the Phylum Mollusca

A

Range in size from microscopic to huge​

Giant clams may weigh 270 kg.​

Evolved in the oceans, and most groups have remained there​

Important source of human food​

Economically significant in other ways​

Pearls are produced in oysters.​

Mother-of-pearl is produced in the shells of abalone.​

Pests – Zebra mussel (Dreissena polymorpha).

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129
Q

Mollusk Body Plan: Mantle and Foot

A

Mantle​

Thick epidermal sheet.​

Bounds mantle cavity.​

Secrete shell (if there is one).​

Foot​

Primary means of locomotion for many.​

Divided into arms or tentacles in cephalopods.

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130
Q

Mollusk Body Plan: Internal Organs

A

Internal organs​

Coelom is highly reduced.​

Limited to small spaces around the excretory organs, heart, and part of the intestine.​

Digestive, excretory, and reproductive organs are concentrated in a visceral mass.​

Ctenidia – gills in aquatic mollusks.​

Also filter food in most bivalves.

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131
Q

Mollusk Body Plan: Shell

A

Shell​

Protects against predators and adverse environments.​

Secreted by outer surface of mantle.​

Clearly not essential – repeated loss or reduction.​

Typical shell has 2 layers of calcium carbonate.​

Internal layer may be mother-of-pearl or nacre.​

Pearls are formed by coating foreign object with nacre to reduce irritation.

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132
Q

Mollusk Body Plan: Radula

A

Radula​

Characteristic of most mollusks.​

Rasping, tonguelike structure used in feeding.​

Used to scrape up algae.​

In predatory gastropods, modified to drill through clam shells.​

In Conus snails, modifies into harpoon with venom gland.​

Bivalves do not have a radula.​

Gills used in filter feeding.

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133
Q

Waste Removal and Circulatory System

A

Nitrogenous waste removal – nephridia​

Consist of cilia-lined openings called nephrostomes.​

Tube to excretory pore to mantle cavity.​

Circulatory system​

Open circulatory system.​

Hemolymph sloshes around hemocoel.​

3-chambered heart.​

Cephalopods have a closed circulatory system.

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134
Q

Mollusk Reproduction

A

Most mollusks are gonochoric (individuals are either male or female)​

A few are hermaphroditic.​

Some oysters change sex.​

Most engage in external fertilization​

Gastropods have internal fertilization.​

Mollusk zygote undergoes spiral cleavage

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135
Q

Mollusk Life Stages

A

Trochophore​

Free-swimming larval stage.​

Veliger​

Second free-swimming larval stage.​

Only in bivalves and most marine snails.​

Both forms drift widely in the ocean

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136
Q

Classes of Mollusks

A

There are 7 or 8 recognized classes; 4 will be discussed here​

Polyplacophora – chitons​

Gastropoda – limpets, snails, slugs​

Bivalvia – clams, oysters, scallops​

Cephalopoda – squids, octopuses, cuttlefishes, and chambered nautilus

137
Q

Class Polyplacophora (Chitons)

A

Marine mollusks that have oval bodies​

8 overlapping dorsal calcareous plates​

Body is not segmented under the plates​

Most chitons are grazing herbivores

138
Q

Class Gastropoda

A

Limpets, snails, slugs​

A primarily marine group – some freshwater, and only terrestrial mollusks​

Most have a single shell – some lost it​

Heads typically have pairs of tentacles with eyes​

Torsion​

Unique among animals.​

Mantle cavity and anus are moved from the posterior to the front.

139
Q

Coiling

A

spiral winding of the shell

140
Q

Nudibranchs

A

Nudibranchs are active predators​

Exposed gills.​

Many secrete distasteful chemicals.​

Some extract nematocysts from cnidarian prey and transfer them to their body surface.

141
Q

Class Bivalvia (Bivalves)

A

Includes clams, scallops, mussels, oysters, and others​

Most marine, some freshwater​

No radula or distinct head​

Have 2 shells (valves) hinged together​

Adductor muscles counter hinge ligament.​

Water enters through inhalant siphon and exits through exhalant siphon

142
Q

Class Cephalopoda

A

More than 700 strictly marine species​

Active marine predators​

Only mollusk with closed circulatory system​

Foot has evolved into a series of arms equipped with suction cups​

Beak-like jaws, toxic saliva.​

Largest relative brain sizes among invertebrates​

Highly developed nervous system

143
Q

The Siphon and the Skin

A

Living cephalopods lack external shell​

Except chambered nautilus.​

Squid and cuttlefish have internal shells.​

Jet propulsion using siphon​

Ink can be ejected from siphon​

Chromatophores allow for changing skin color for camouflage or communication

144
Q

Annelids (Annelida)

A

Segmented worms​

Body built of repeated units​

Allows for specialization​

Segmentation may have evolved multiple times

145
Q

Annelid Features

A

Body plan​

Head has well-developed cerebral ganglion.​

Sensory organs in ringlike segments.​

Many species have eyes.​

Segments divided internally by septa.​

Each segment has a pair of excretory organs, a ganglion, and locomotory structure.​

Closed circulatory system.​

Ventral nerve cord.

146
Q

Other Annelid Features

A

Each part of digestive tract specialized for different function​

Locomotion​

Coelomic fluid creates a hydrostatic skeleton.​

Alternating muscle contractions allows complex movements.​

Chaetae – bristles of chitin found in most groups.​

Closed circulatory system​

Gas exchange by diffusion across body surfaces.​

Excretory system – nephridia similar to mollusks

147
Q

Annelid Clades

A

Roughly 32,000 described species of annelids occur in many habitats​

Formerly classified as Polychaeta, Oligochaeta and Hirudinea​

Now grouped into 2 clades​

Errantia​

Sedentaria

148
Q

Errantia

A

Include clamworms, scaleworms, lugworms, sea mice, tubeworms, and others​

Have paired parapodia on most segments​

Used in locomotion or gas exchange.​

Chaetae on parapodia.​

May have gonads in in most segments or just certain segments​

External fertilization.​

Trochophore larva.

149
Q

Sedentaria

A

Little movement​

May burrow or live in tubes​

May feed using tentacles or may filter-feed

150
Q

Riftia

A

Adults are gutless​

Sulfur-oxidizing bacteria housed on Riftia synthesize organic compounds used by worm​

Found near hydrothermal vents

151
Q

Clade Clitellata

A

Clitellum found in all members​

Earthworms​

Head not well differentiated.​

No parapodia.​

Few chaetae project from body wall.​

Hermaphroditic but cross-fertilize.​

Clitellum secretes mucus cocoon.​

152
Q

Earthworms

A

100-175 similar segments​

Chaetae project from body wall​

Eat their way through the soil​

No eyes​

Can sense light, touch, and also have chemoreceptors​

Hermaphroditic cross fertilizers

153
Q

Leeches

A

Occur mostly in freshwater​

Usually flattened dorsoventrally​

Hermaphroditic and cross-fertilization​

Clitellum develops only during breeding season.​

Coelom reduced, not divided into segments​

Suckers at both ends of body​

No chaetae (except for one species)​

Some eat detritus, others suck blood

154
Q

Ribbon Worms (Nemertea)

A

About 2400 species of cylindrical to flattened very long worms

155
Q

Nemertean Features

A

Most are marine; a few species live in fresh water and humid terrestrial habitats​

Lineus longissimus has been reported to measure 60 m in length – the longest animal known!​

Body plan resembles a flatworm​

Has a complete gut​

Rhynchocoel – fluid filled coleomic cavity

156
Q

Other Nemertean Features

A

Gonochoric with sexual reproduction​

Asexual reproduction through fragmentation.​

Blood flows entirely in vessels.

157
Q

Bryozoa and Brachiopoda

A

Mostly marine animals​

Both characterized by lophophore​

Circular or U-shaped ridge around the mouth with 1–2 rows of ciliated tentacles.​

Functions in gas exchange and feeding.​

May be convergent evolution.​

Phylogeny a puzzle

158
Q

Phylum Bryozoa

A

Also called “moss animals”​

Bryozoans are small and live in colonies​

Their anus opens near their mouth​

Individuals secrete a tiny chitinous chamber called a zoecium attached to substrate​

May deposit calcium carbonate (formed reefs in past).​

Asexual reproduction occurs frequently by budding

159
Q

Phylum Brachiopoda

A

Brachiopods or lamp shells​

Have two calcified shells​

Dorsal and ventral (not lateral as in bivalves).​

Lophophore lies on the body, between the shells.​

Phoronids were once a separate phylum​

Each individual secretes a chitinous tube.​

Extends lophophore to feed.

160
Q

Nematode Characteristics

A

Vinegar eels, eelworms, and other roundworms​

Members of this phylum are found everywhere – abundant and diverse​

Marine, freshwater, parasites, free-living

161
Q

Additional Nematode Characteristics

A

Bilaterally symmetrical and unsegmented​

Covered by a flexible, thick cuticle that is molted as they grow​

Digestive system well developed​

Stylets – piercing organs near mouth.​

Pharynx – creates sucking action.​

Anus.

162
Q

Reproduction and Composition

A

Sexual reproduction​

Most gonochoric.​

Sexual dimorphism – male smaller with hooked end.​

Internal fertilization.​

Indirect development – egg, larva, adult.​

Cellular composition​

Adults consist of a fixed number of cells.​

Caenorhabditis elegans has only 959 cells.​

Important in genetic and developmental studies.

163
Q

Lifestyles

A

Many are active hunters, preying on protists and other small animals​

Others are parasites of plants​

Still others live within the bodies of larger animals​

Largest known nematode, which can attain a length of 9 m, parasitizes the placenta of sperm whales.

164
Q

Nematodes and Human Disease

A

About 50 species cause human diseases​

Hookworms​

Common in southern U.S.​

Produce anemia.​

Trichinella causes trichinosis​

Forms cysts in muscles.​

Infection from eating undercooked meat.

165
Q

Additional Nematodes Associated with Human Disease

A

Pinworms, Enterobius vermicularis​

Infects 11% of U.S. population.​

Causes itching of the anus.​

Ascaris lumbricoides – intestinal roundworm​

Infects 1 in 6 worldwide.​

Adult female can be 30 cm long.​

Rare in areas with modern plumbing.​

Serious tropical nematode diseases​

Filariasis.​

Elephantiasis.

166
Q

Arthropod Characteristics

A

By far the most successful animals​

Well over 1,200,000 species (2/3 of all named species).​

Arthropods affect all aspects of human life​

Divided into four extant classes​

Chelicerata.​

Crustacea.​

Hexapoda.​

Myriapoda.

167
Q

Chelicerata

A

Anterior appendages (chelicera) are specialized as pincers or fangs.

168
Q

Crustacea

A

Mouthparts are mandibles; appendages are biramous (“two-branched”); the head has two pairs of antennae.

169
Q

Hexapoda

A

Mouthparts are mandibles; the body consists of three regions: a head with one pair of antennae, a thorax, and an abdomen; appendages are uniramous (“single-branched”).

170
Q

Arthropod Success: Segmentation and Exoskeleton

A

Part of arthropod success explained by​

Segmentation​

In some classes specialized into tagmata.​

Head, thorax, abdomen.​

Head and thorax may be fused into cephalothorax or prosoma.​

Exoskeleton​

Made of chitin and protein.​

Protects against water loss.​

Must undergo ecdysis – molting.

Jointed appendages​

May be modified into antennae, mouthparts, or wings.​

Can be extended and retracted.

170
Q

Myriapoda

A

Mouthparts are mandibles; the body consists of a head with one pair of antennae, and numerous segments, each bearing paired uniramous appendages.

171
Q

Circulatory and Nervous Systems

A

Open circulatory system​

Nervous system​

Double chain of segmented ganglia.​

Ventral ganglia control most activities.​

Can eat, move, or copulate with brain removed.

172
Q

Arthropod Eyes

A

Compound eyes are found in many arthropods​

Composed of independent visual units called ommatidia.​

Other arthropods have simple eyes, or ocelli​

May be in addition to compound eyes.​

Have single lenses.​

Distinguish light from darkness.

173
Q

Respiratory system

A

Many marine arthropods have gills​

Some tiny arthropods lack any structure for gas exchange​

Terrestrial arthropods use tracheae​

Branch into tracheoles in direct contact with cells.​

Connected to the exterior by spiracles.​

Valves control water loss.​

Many spiders use book lungs​

Leaflike plates.

174
Q

Excretory system

A

In aquatic arthropods much of the waste diffuses out of gills​

Terrestrial insects and some others use Malpighian tubules​

Eliminates nitrogenous wastes as concentrated uric acid or guanine.​

Efficient conservation of water.

175
Q

Class Chelicerata

A

Spiders, ticks, mites, scorpions, daddy long-legs, horseshoe crabs, sea spiders​

Most anterior appendages called chelicerae​

May function as fangs or pincers.​

Body divided into 2 tagmata​

Anterior prosoma bearing all appendages.​

Pedipalps and 4 pairs of walking legs.​

Posterior opisthosoma contains reproductive organs.

176
Q

Order Araneae (spiders)

A

About 35,000 species​

Particularly important as predators​

Many spiders catch their prey in silk webs​

Silk protein forced out of spinnerets found on the posterior of the abdomen.​

Other spiders actively hunt their prey​

All spiders have poison glands with channels through their chelicerae

177
Q

Order Acari (mites and ticks)

A

Most diverse of the chelicerates​

Predators and parasites​

Most mites are small​

Cephalothorax and abdomen are fused into an unsegmented ovoid body.​

Ticks are larger​

Blood-suckers.​

Can carry many diseases​

Rocky Mountain spotted fever, Lyme disease.

178
Q

Class Crustacea

A

Largely marine, some freshwater​

Crabs, shrimps, lobsters, barnacles, crayfish, copepods, pill bugs, sand fleas​

Have three tagmata​

Cephalon and thorax fused to form a cephalothorax.​

2 pairs of antennae, 3 pairs of appendages for chewing, and various pairs of legs​

Most appendages are biramous.​

Gas exchange through gills or across cuticle

179
Q

Crustacean Reproduction

A

All crustaceans but barnacles are gonochoric​

Many kinds of copulation​

Nauplius stage​

Several stages before maturity.​

Evidence of common ancestor for diverse group.

180
Q

Decapod crustaceans

A

Shrimps, lobsters, crabs, and crayfish​

Have 10 feet – 5 pairs of thoracic appendages​

Exoskeleton usually enforced with CaCO3​

Cephalothorax covered by carapace​

Lobsters and crayfish​

Swimmerets used in reproduction and swimming.​

Uropods paddle on either side of telson.​

Crab has small abdomen held under carapace

181
Q

Order Cirripedia (Barnacles)

A

Sessile as adults​

Captures food with feathery legs​

Hermaphroditic

182
Q

Class Hexapoda

A

Insects are by far the largest group of animals​

Number of species and number of individuals.​

More than half of all named animal species​

Approximately one billion billions insects are alive at any one time

183
Q

Coleoptera

A

Two pairs of wings, the front one hard, protecting the rear one; heavily armored exoskeleton; biting and chewing mouthparts. Complete metamorphosis. The most diverse animal order.

184
Q

Lepidoptera

A

Two pairs of broad, scaly, flying wings, often brightly colored. Hairy body; tubelike, sucking mouthparts. Complete metamorphosis.

185
Q

Diptera

A

Front flying wings transparent; hindwings reduced to knobby balancing organs called halteres. Sucking, piercing, or lapping mouthparts; some bite people and other mammals. Complete metamorphosis.

186
Q

Hymenoptera

A

Two pairs of transparent flying wings; mobile head and well-developed compound eyes; often possess stingers; chewing and sucking mouthparts. Many social. Complete metamorphosis.

187
Q

Hemiptera

A

Wingless or with two pairs of wings; piercing, sucking mouthparts, with which some draw blood, some feed on plants. Simple metamorphosis.

188
Q

Orthoptera

A

Wingless or with two pairs of wings; among the largest insects; biting and chewing mouthparts in adults. Third pair of legs modified for jumping. Simple metamorphosis.

189
Q

Odonata

A

Two pairs of transparent flying wings that cannot fold back; large, long, and slender body; chewing mouthparts. Simple metamorphosis.

190
Q

Isoptera

A

Two pairs of wings, but some stages wingless; chewing mouthparts; simple metamorphosis. Social organization; labor divided among several body types. Some are among the few types of animals able to digest wood. Incomplete metamorphosis.

191
Q

Siphonaptera

A

Wingless; flattened body with jumping legs; piercing and sucking mouthparts. Small; known for irritating bites. Complete metamorphosis.

192
Q

Three body regions

A

Head​

Thorax has three segments, each with a pair of legs​

May have one or two pairs of wings – outgrowths of body wall.​

Abdomen​

Most insects have compound eyes

193
Q

Insect Mouthparts

A

Insect mouthparts all have the same basic structure​

Modifications reflect feeding habits

194
Q

Internal organization

A

The digestive tract is a tube​

Digestion takes place in stomach (midgut)​

Excretion tales place through Malpighian tubules​

Winged insects have dilated tracheae forming air sacs​

Form bellows to force air deep into body.​

spiracles through which air enters the tracheal system.​

Some parasitic or aquatic forms have permanently closed spiracles – use diffusion

195
Q

Sensory receptors

A

Sensory setae are hairlike structures​

Detect chemical and mechanical signals.​

Tympanum – a thin membrane associated with tracheal air sacs​

Detect sound.​

May also use sensory hairs to detect sound.​

Pheromones also used for communication​

Mating signals, trail markers.

196
Q

Insect life histories

A

Many insects undergo metamorphosis​

Simple metamorphosis (grasshoppers)​

Immature stages similar to adults.​

Complete metamorphosis (butterflies)​

Immature larva are wormlike.​

A resting stage, pupa or chrysalis, precedes the final molt into adult form.

197
Q

Class Myriapoda

A

Centipedes (subclass Chilopoda)​

One pair of appendages per segment.​

Carnivorous – poison fangs.​

Millipedes (subclass Diplopoda)​

Two pairs of appendages per segment.​

Each segment is a tagma of 2 segments.​

Herbivores.​

Complex glands produce bad-smelling fluid in defense.

198
Q

Myriapod Characteristics

A

Head regions followed by numerous segments​

Gonochoric, internal fertilization, lay eggs​

Young add segments as they grow.

199
Q

Phylum Echinodermata

A

Exclusively marine​

Deuterostomes with an endoskeleton​

Pentaradial symmetry​

Sea stars, brittle stars, sea urchins, sand dollars, sea cucumbers

200
Q

Origin of the Echinoderms

A

Origin remains unclear​

Thought to have evolved from bilaterally symmetrical ancestors because larvae are bilaterally symmetrical.

201
Q

Symmetry and Endoskeleton

A

Symmetry​

Pentaradial as adult, bilateral as larva.​

Oral surface defines mouth.​

All systems organized with branches radiating from center.​

Nervous system is nerve ring with branches.​

No centralization of function.​

Endoskeleton​

Epidermis covers endoskeleton.​

Composed of calcium carbonate ossicles.​

May be tightly or loosely joined.​

All members have mutable collagenous tissue.

202
Q

Water-vascular System

A

Water-vascular system​

Radially organized.​

Radial canal extends from ring canal into each body branch.​

Water enters through madreporite.​

Flows through stone canal to ring canal.​

Tube feet – may or may not have suckers.​

Ampulla – muscular sac at base.​

Used in movement, feeding, gas exchange.

203
Q

Regeneration and Reproduction

A

Regeneration​

Many able to regenerate lost parts.​

Some reproduce asexually by splitting.​

Most reproduction is sexual​

Gonochoric.​

Gametes released into water.​

Free-swimming larvae.​

Each class has a characteristic type of larva.

204
Q

Class Asteroidea

A

Sea stars and sea daisies​

Important predators in many marine systems​

Most have 5 arms, some have multiples of 5

205
Q

Classes Crinoidea & Holothuroidea

A

Class Crinoidea: sea lilies and feather stars​

Class Holothuroidea: sea cucumbers

206
Q

Class Echinoidea

A

Sea urchins and sand dollars​

Lack arms​

Double rows of tube feet​

Protective moveable spines

207
Q

Class Ophiuroidea

A

Brittle stars​

Largest class​

Arms are equal diameter their entire length​

Arms are easily autotomized

208
Q

Phylum Chordata

A

Chordate endoskeleton is very different than echinoderm endoskeleton​

Chordate endoskeleton is truly internal.​

Echinoderm endoskeleton is functionally similar to arthropod exoskeleton.​

Fishes, amphibians, reptiles, birds, and mammals

209
Q

Chordate Features

A

Nerve cord​

Notochord​

May be replaced by vertebral column.​

Pharyngeal slits​

Pharyngeal pouches present in all vertebrate embryos.​

Postanal tail

210
Q

Other Chordate Characteristics

A

All chordates have all four of these characteristics at some time in their lives​

Other characteristics also distinguish chordates​

Chordate muscles are arranged in segmented blocks called somites.​

Most chordates have an internal skeleton against which the muscles work.

211
Q

Chordate Subphyla

A

Phylum Chordata can be divided into three subphyla​

Urochordata–Nonvertebrates​

Cephalochordata–Nonvertebrates​

Vertebrata

212
Q

Subphylum Urochordata

A

Tunicates and salps are marine animals​

Larvae are tadpolelike and have notochord and nerve cord​

Are free-swimming but do not feed.​

Adults typically lose the tail and notochord​

Are immobile filter-feeders.​

Many secrete a tunic (cellulose sac) that surrounds the animal.​

213
Q

Subphylum Cephalochordata

A

Lancelets are scaleless chordates​

Notochord persists throughout animal’s life​

Spend most of their time partly buried​

Have no distinguishable head​

Feed on plankton using cilia-generated currents​

Closest relatives to vertebrates

214
Q

Subphylum Vertebrata

A

Vertebrates are chordates with a spinal column​

Distinguished from nonvertebrates by​

Vertebral column – Encloses and protects the dorsal nerve cord.​

Head – Distinct and well-differentiated possessing sensory organs.

215
Q

More Vertebrate Characteristics

A

Neural crest – unique group of embryonic cells that forms many vertebrate structures​

Internal organs – liver, kidneys, endocrine glands, heart, and closed circulatory system​

Endoskeleton – made of cartilage or bone​

Makes possible great size and extraordinary movement.

216
Q

History of the Vertebrates​

A

The first vertebrates appeared in the oceans about 530 M Y A​

Mouth at one end, fin at the other.​

Jawed fishes soon became dominant​

Amphibians invaded the land​

Reptiles replaced them as the dominant land vertebrates​

Birds and mammals became dominant after Cretaceous mass extinction

217
Q

Fishes

A

Most diverse vertebrate group​

Over half of all vertebrates​

Provided the evolutionary base for invasion of land by amphibians

218
Q

Fishes Characteristics

A

Vertebral column​

Hagfish and lamprey exceptions.​

Jaws and paired appendages​

Hagfish and lamprey exceptions.​

Internal gills​

Single-loop blood circulation​

Nutritional deficiencies​

Inability to synthesize aromatic amino acids has been inherited by all their vertebrate descendants.

219
Q

Actinistia

A

One of two types of living lobe-finned fishes (lungfishes being the other), coelacanths have remained morphologically unchanged since the Mesozoic. Actinistia and Dipnoi used to be considered subclasses of the Sarcopterygii, but because tetrapods (legged vertebrates) arose from a lobe-finned fish, the Sarcopterygii is paraphyletic

220
Q

Dipnoi

A

These lobe-finned fishes can breathe air and live for extended periods out of water.

221
Q

Actinopterygii

A

Most diverse group of vertebrates; swim bladders and bony skeletons; paired fins supported by bony rays

222
Q

Chondrichthyes ​

A

Cartilaginous skeletons; no swim bladders; internal fertilization

223
Q

Petromyzontida

A

Largely extinct group of jawless fishes with no paired appendages; parasitic and nonparasitic types; all breed in freshwater

224
Q

Myxini

A

Jawless fishes with no paired appendages; scavengers; mostly blind, but having a well-developed sense of smell

225
Q

Placodermi

A

Jawed fishes with heavily armored heads; many were quite large​

226
Q

Acanthodii and Ostracoderms

A

Fishes with (acanthodians) or without (placoderms) jaws; paired fins supported by sharp spines; head shields made of bone; rest of skeleton cartilaginous

227
Q

History of the Fishes

A

The first fishes had mouths with no jaws​

Agnatha extant as hagfish (class Myxini) and lampreys (class Cephalaspidomorphi).​

Ostracoderms are now extinct.​

The development of jaws occurred in the late Silurian period​

Jaws evolved from the anterior gill arches that were made of cartilage.

228
Q

Placoderms

A

Armored fishes (placoderms) and spiny fishes both had jaws​

Spiny fish were common during early Devonian – replacing ostracoderms.​

Cartilage skeleton but skin had small plates of bone.​

Extinct at close of Permian.​

Placoderms became common in late Devonian.​

Jaw more improved than in spiny fishes.​

Upper jaw fused to the skull and the skull hinged on the shoulder.​

Extinct by end of period.

229
Q

Emergence of Sharks and Bony Fish

A

At the end of the Devonian period, essentially all of these pioneer vertebrates disappeared, replaced by sharks and bony fishes in one of several mass extinctions​

Sharks and bony fishes first evolved in the early Devonian, 400 M Y A​

Jaw was improved even further allowing the mouth to open much wider than was previously possible

230
Q

Class Chondrichthyes

A

Sharks, skates, rays​

Became the dominant sea predators in the Carboniferous period (360–280 M Y A)​

Cartilage skeleton “calcified” with granules of calcium carbonate​

Light, strong skeleton.

231
Q

Teeth and the Lateral Line System

A

Sharks were among the first vertebrates to develop teeth​

Evolved from rough scales on mouth’s skin.​

Easily lost but continuously replaced.​

Sharks (and bony fishes) have a fully developed lateral line system​

Series of sensory organs under the skin that detects changes in pressure waves.

232
Q

Shark Reproduction & Development

A

Reproduction in sharks differs from that of other fishes​

Eggs are fertilized internally.​

Most pups are born alive.​

A few species do lay fertilized eggs.​

Sharks have long gestation periods and relatively few offspring​

Therefore, are not able to recover quickly from population declines.

233
Q

Bony fishes

A

Evolved at the same time as sharks (400 M Y A)​

However, they adopted a heavy internal skeleton made completely of bone.​

Bony fishes are the most species-rich group of all vertebrates (> 30,000 living species)​

Significant adaptations include swim bladder and gill cover

234
Q

Swim Bladder and Gill Cover

A

Swim bladder​

Gas-filled sac that allows bony fishes to regulate their buoyant density.​

In most modern fish, filled and drained with gases internally.​

Gill cover​

Hard plate, the operculum, covers gills.​

Flexing plate permits water pumping over gills.​

Efficient bellows system when stationary.

235
Q

Gas Regulation

A

Gases are taken from the blood, and the gas gland secretes the gases into the swim bladder. Gas is released from the bladder by a muscular valve, the oval body.

236
Q

Three Major Groups of Bony Fishes

A

Ray-finned fishes, lungfish, and coelacanths​

Ray-finned fishes (class Actinopterygii)​

Parallel bony rays support and stiffen each fin.​

There are no muscles within the fins.​

Lobe-finned fishes​

Lungfish (class Dipnoi) and Coelacanths (class Actinistia)​

Have paired fins that consist of a long fleshy muscular lobe.​

Supported by central core of bones with fully articulated joints.

237
Q

5 distinguishing amphibian features

A

Legs – adaptation to life on land​

Lungs​

Cutaneous respiration – supplement lungs​

Pulmonary veins – separate pulmonary circuit allows higher pressure blood to tissues​

Partially divided heart – improves separation of pulmonary and systemic circuits

238
Q

Successful Invasion of Land by Vertebrates

A

Required several adaptations​

Legs to support body’s weight.​

Lungs to extract oxygen from air.​

Redesigned heart and circulatory system to drive larger muscles.​

Reproduction still in water to prevent egg drying.​

System to prevent whole body desiccation.

239
Q

Ichthyostega

A

Amphibians evolved from lobe-finned fish​

Ichthyostega was one of the first amphibians​

Sturdy forelegs, flipper-shaped hindlimbs​

Moved like a seal.​

Long, broad, overlapping ribs form solid cage for lungs and heart

240
Q

Tiktaalik

A

In 2006, a transitional fossil was found between fish and Ichthyostega​

Had gills and scales like a fish, but a neck like an amphibian​

Shoulder, forearm, and wrist bones were like those of amphibians, but at the end of the limb was a lobed fin, rather than the toes of an amphibian​

241
Q

Anura

A

Compact, tailless body; large head fused to the trunk; rear limbs specialized for jumping

242
Q

Caudata

A

Slender body; long tail and limbs set out at right angles to the body

243
Q

Apoda

A

Tropical group with a snakelike body; no limbs; little or no tail

244
Q

3 Modern Amphibian groups

A

Over 7000 species descended from 3 different families that survived the Age of the Dinosaurs​

Order Anura: frogs and toads​

Order Caudata: salamanders​

Order Apoda: caecilians

245
Q

Order Anura (frogs and toads)

A

Frogs have smooth, moist skin and long legs​

Most live in or near water, aquatic tadpole stage before metamorphosis into adult.​

Toads have bumpy, dry skin and short legs​

Most live in dry environments.​

Not a monophyletic group.​

Eggs laid in water – lack watertight membranes​

Eggs fertilized externally.​

Tadpole – swimming larval form.​

Gradual metamorphosis into adult form.

246
Q

Order Caudata and Order Apoda

A

Order Caudata (salamanders)​

Have long bodies, tails, and smooth, moist skin.​

Live in moist places.​

Eggs are fertilized internally – sperm packet.​

Larvae similar to adults.​

Order Apoda (caecilians)​

Tropical, burrowing amphibians.​

Legless with small eyes and jaws with teeth.​

Fertilization is internal.

247
Q

Class Reptilia

A

Over 10,000 living species​

All living reptiles exhibit three key features​

Amniotic eggs, which are watertight​

Dry skin, which covers body and prevents water loss​

Thoracic breathing, which increases lung capacity​

248
Q

Amniotic Eggs

A

Reptiles, birds, and mammals are amniotes​

The amniotic egg has four membranes​

Chorion.​

Outermost layer, allows gas exchange.​

Amnion.​

Encases embryo in fluid-filled cavity.​

Yolk sac.​

Provides food.​

Allantois.​

Contains excreted wastes from embryo.

249
Q

Squamata, suborder Sauria

A

Limbs set at right angles to body; anus is in transverse (sideways) slit; most are terrestrial

250
Q

Squamata, suborder Serpentes

A

No legs; move by slithering; scaly skin is shed periodically in a single piece; most are terrestrial; snakes evolved from lizards, making lizards a paraphyletic group

251
Q

Rhynchocephalia

A

Sole survivors of a once successful group that largely disappeared before dinosaurs; fused, wedgelike, socketless teeth; primitive third eye under skin of forehead

252
Q

Chelonia

A

Armored reptiles with shell of bony plates to which vertebrae and ribs are fused; sharp, horny beak without teeth

253
Q

Crocodylia

A

Large reptiles with four-chambered heart and socketed teeth; anus is a longitudinal (lengthwise) slit; closest living relatives to birds​

254
Q

Ornithischia

A

Dinosaurs with two pelvic bones facing backward, like a bird’s pelvis; herbivores; legs under body

255
Q

Saurischia

A

Dinosaurs with one pelvic bone facing forward, the other back, like a lizard’s pelvis; both plant- and flesh-eaters; legs under body; birds evolved from Saurischian dinosaurs.

256
Q

Pterosauria

A

Flying reptiles; wings were made of skin stretched between fourth fingers and body; wingspans of early forms typically 60 cm, later forms nearly 8 m

257
Q

Plesiosaura

A

Barrel-shaped marine reptiles with sharp teeth and large, paddle-shaped fins; some had snakelike necks twice as long as their bodies

258
Q

Ichthyosauria

A

Streamlined marine reptiles with many body similarities to sharks and dolphins

259
Q

Anapsids, Synapsids, and Diapsids

A

Reptiles are distinguished by the number of holes on side of the skull behind eye orbit​

0 (anapsids), 1 (synapsids), 2 (diapsids).

260
Q

Pelycosaurs

A

First land vertebrates to kill beasts their own size.

261
Q

Therapsids

A

Replaced pelycosaurs about 250 M Y A​

May have been endotherms​

“Mammal-like” reptile​

Most became extinct 170 M Y A​

One group survived and has living descendants today – the mammals

262
Q

Diapsids

A

A number of different diapsids occurred in the Triassic period (248–213 M Y A)​

Diapsids have skulls with two pairs of holes on each side

263
Q

Archosaurs

A

Therapsids were replaced by diapsids about 230 M Y A​

Archosaurs were the first land vertebrates to be bipedal​

Gave rise to crocodiles, pterosaurs, dinosaurs, and birds.​

264
Q

Dinosaurs

A

Dinosaurs dominated for over 150 million years​

Became extinct 66 M Y A.​

Except bird descendents.​

Asteroid’s impact.

265
Q

Modern Reptiles

A

Modern reptiles developed two important characteristics​

Internal fertilization.​

Sperm fertilizes egg before protective membranes are formed.​

Improved circulation.​

Oxygen is provided to the body more efficiently.​

Septum in heart extended to create partial wall.​

Crocodiles, birds, and mammals have completely divided 4-chambered heart.

266
Q

All living reptiles are ectothermic

A

Obtain heat from external sources​

Regulate body temperature by moving in and out of sunlight​

Compare to endothermic animals that generate their own heat internally

267
Q

Reptile Taxonomy

A

There are four surviving orders of reptiles​

Chelonia (turtles and tortoises).​

Rhynchocephalia (tuataras).​

Squamata (lizards and snakes).​

Crocodylia (crocodiles and alligators).​

More than 10,000 species​

Reptiles occur worldwide except in the coldest regions, where it is impossible for ectotherms to survive

268
Q

Order Chelonia

A

Differ from all other reptiles because their bodies are encased within a protective shell​

Carapace (dorsal) and plastron (ventral).​

Tortoises are terrestrial while turtles are mostly aquatic​

Both lack teeth but have sharp beaks​

Marine turtles must return to land to lay eggs

269
Q

Order Rhynchocephalia

A

Contains a single species–the tuataras​

Large, lizard-like animals about half a meter long​

Only found on islands near New Zealand​

Parietal eye​

Eye with lens and retina concealed under layer of scales on top of head.

270
Q

Order Squamata

A

A characteristic of this order is the presence of paired copulatory organs in the male​

Snakes – 3,500 species​

Lack limbs, movable eyelids, and external ears.​

Lizards​

Iguanas, chameleons, geckos, anoles.​

Many have ability to regenerate lost tails.

271
Q

Order Crocodylia

A

28 species of large, primarily aquatic carnivorous reptiles​

Crocodiles, alligators, caimans, gavials.​

Crocodiles​

Typically nocturnal.​

Tropical and subtropical regions.​

Alligators – only 2 species​

Southern US and China.​

Bodies well adapted to stealth hunting​

Eyes on top of head, nostrils on top of snout, enormous mouth, strong necks.

272
Q

Crocodiles and Birds

A

Crocodiles resemble birds far more than they do other living reptiles​

Build nests and care for their young.​

Have a 4-chambered heart.

273
Q

Passeriformes

A

Well-developed vocal organs; perching feet; dependent young

274
Q

Apodiformes

A

Fast fliers; short legs; small bodies; rapid wing beat

275
Q

Piciformes

A

Grasping feet; chisel-like, sharp bills can break down wood

276
Q

Psittaciformes

A

Large, powerful bills for crushing seeds; well-developed vocal organs

277
Q

Charadriiformes

A

Shorebirds; long, stiltlike legs; slender, probing bills​

278
Q

Columbiformes

A

Perching feet; rounded, stout bodies

279
Q

Falconiformes

A

Carnivorous; keen vision; sharp, pointed beaks for tearing flesh; active during the day

280
Q

Galliformes

A

Often limited flying ability; rounded bodies

281
Q

Gruiformes

A

Marsh birds; long, stiltlike legs; diverse body shapes; marsh-dwellers

282
Q

Anseriformes

A

Waterfowl; webbed toes; broad bill with filtering ridges

283
Q

Strigiformes

A

Nocturnal birds of prey; strong beaks; powerful feet

284
Q

Ciconiiformes

A

Waders; long-legged; large bodies

285
Q

Procellariformes

A

Seabirds; tube-shaped bills; capable of flying for long periods of time

286
Q

Sphenisciformes

A

Marine; modified wings for swimming; flightless; found only in southern hemisphere; thick coats of insulating feathers

287
Q

Dinornithiformes

A

Flightless; small; confined to New Zealand

288
Q

Struthioniformes

A

Powerful running legs; flightless; only two toes; very large

289
Q

Birds and Reptiles

A

Birds still retain many reptilian traits​

Amniotic eggs.​

Have scales on legs.​

Two major distinguishing traits​

Feathers.​

Modified scales of keratin.​

Provide lift for flight and conserve heat.​

Flight skeleton.​

Bones are thin and hollow.​

Many are fused for rigidity – anchor strong flight muscles.​

Keeled breastbone provides attachment site for flight muscles.

290
Q

Feathers

A

Feathers developed from reptile scales​

Linked structures provide continuous surface and a sturdy but flexible shape

291
Q

Archaeopteryx

A

Archaeopteryx is the first known bird​

Had skull with teeth, long reptilian tail.​

Feathers on wings and tail.​

Forelimbs nearly identical to those of theropods.​

Feather probably evolved for insulation

292
Q

Theropod Descendants

A

Most paleontologists agree that birds are the direct descendants of theropod dinosaurs

293
Q

Birds exhibit three evolutionary novelties

A

Feathers​

Hollow bones​

Physiological mechanisms for flight

294
Q

Confuciornis

A

Fossil is from early Cretaceous​

A few million years after Archaeopteryx lived.​

A diverse array of bird species were present.​

Toothed birds with hollow bones and breastbones necessary for flight​

Long tail feathers are lacking in some fossils​

May be a trait present only in one sex.​

This is seen in some modern birds.

295
Q

Modern Birds​

A

Diverse but share characteristics​

Beaks and feet provide information about habits and food​

Owls: curved talons, sharp beaks for tearing prey.​

Ducks: flat beaks to shovel through mud.​

Finches: short, thick for crushing seed.

296
Q

Adaptations for flight

A

-Efficient respiration​

Air passes all the way through lungs in a single direction.​

-Efficient circulation​

4-chambered heart so muscles receive fully oxygenated blood.​

Rapid heartbeat.​

-Endothermy​

Body temperature (40 to 42°C) permits higher metabolic rate.

297
Q

Class Mammalia

A

There are about 5,000 species of mammals​

Lowest number among 5 vertebrate classes.​

Almost 4,000 species are rodents, bats, shrews, or moles.

298
Q

2 fundamentally mammalian traits

A

Hair​

Long, keratin-rich filaments that extend from hair follicles.​

Insulation, camouflage, sensory structure.​

Mammary glands​

Females possess mammary glands that secrete milk.

299
Q

Other Notable Features of Mammals

A

Endothermy depends on higher metabolic rate​

4-chambered heart.​

Respiration using diaphragm.​

Placenta in most mammals​

Specialized organ that brings fetal and maternal blood into close contact.

300
Q

Other Adaptations: Teeth

A

The mammalian lineage also gave rise to several adaptations in some groups​

Specialized teeth​

Different types of teeth are highly specialized to match particular eating habits.​

Contrast carnivore teeth to herbivore teeth.

301
Q

Other Adaptations: Digestion and Development

A

Digestion of plants​

Herbivorous mammals rely on mutualistic partnerships with bacteria for cellulose breakdown.​

Development of hooves and horns​

Hooves are specialized keratin pads.​

Horns are bone surrounded by keratin.​

Antlers are made of bone, not keratin.

302
Q

Other Adaptations: Flight

A

Flying mammals: Bats​

Only mammals capable of powered flight.​

Wing is a leathery membrane of skin and muscle stretched over 4 finger bones.​

Navigate in the dark by echolocation.

303
Q

History of Mammals

A

Mammals have been around since the time of the dinosaurs, about 220 M Y A​

Tiny, shrewlike, insect-eating, tree-dwelling creatures.​

May have been nocturnal – large eye sockets.​

Mammals reached their maximum diversity late in the Tertiary period (about 15 M Y A)​

After mass extinction of dinosaurs.​

Decline in the total number of mammalian species over last 15 million years.

304
Q

Major Subclasses of Mammals

A

Prototheria (most primitive)​

Lay shelled eggs.​

Only living group is the monotremes.​

Theria​

Viviparous – young are born alive.​

Two living groups.​

Marsupials or pouched mammals.​

Placental mammals.

305
Q

Monotremes

A

Lay shelled eggs​

Like reptiles have single opening (cloaca) for feces, urine, and reproduction​

Lack well-developed nipples​

Only three living species​

Duck-billed platypus.​

2 echidna species.

306
Q

Marsupials

A

Major difference is pattern of embryonic development​

Short-lived placenta.​

After birth, it crawls into marsupial pouch, latches onto nipple, and continues to develop.​

Kangaroo – isolation of Australia​

Opossum – only North American marsupial

307
Q

Placental Mammals

A

Produce a true placenta that nourishes embryo throughout its development​

Forms from both fetal and maternal tissues.​

Young undergo a considerable period of development before they are born.​

Includes most living mammals​

308
Q

Rodentia

A

Small plant-eaters; chisel-like incisor teeth

309
Q

Chiroptera

A

Flying mammals; primarily fruit- or insect-eaters; elongated fingers; thin wing membrane; mostly nocturnal; navigate by sonar

310
Q

Eulipotyphla

A

Small, burrowing mammals; insect-eaters; spend most of their time underground

311
Q

Primates

A

Primarily tree-dwellers; large brain size; binocular vision; opposable thumb

312
Q

Artiodactyla

A

Hoofed mammals with two or four toes; most species herbivorous ruminants

313
Q

Carnivora

A

Carnivorous predators; teeth adapted for shearing flesh; no native families in Australia

314
Q

Lagomorpha

A

Four upper incisors (rather than the two seen in rodents); hind legs often longer than forelegs, an adaptation for bounding

315
Q

Cetacea

A

Fully marine mammals; streamlined bodies; front limbs modified into flippers; no hindlimbs; blowholes on top of head; no hair except on muzzle

316
Q

Edentata

A

Insectivorous; many are toothless, but some have small, peglike teeth

317
Q

Perissodactyla

A

Hoofed mammals with odd number of toes; herbivorous teeth adapted for chewing

318
Q

Proboscidea

A

Long-trunked herbivores; two upper incisors elongated as tusks; largest living land animal

319
Q

Evolution of Primates

A

Evolved two features that allowed them to succeed in an arboreal environment​

Grasping fingers and toes​

First digit (thumb) is opposable in many.​

Binocular vision​

Eyes are shifted toward the front of the face.​

Lets brain judge distances precisely.

320
Q

Living Primates: Prosimians

A

Now considered to be paraphyletic​

Lemurs, lorises and tarsiers​

Large eyes with increased visual acuity​

Most are nocturnal

321
Q

Living Primates: Anthropoids

A

Include monkeys, apes, and humans​

Almost all diurnal​

Changes in eye design include color vision.​

Expanded brain​

Live in groups with complex social interactions​

Care for young for extended period.​

Long period of learning and brain development.

322
Q

Anthropoid History

A

30 MYA​

New World monkeys migrated to South America.​

All arboreal; many have prehensile tail.​

Old World monkeys and hominids remained in Africa.

323
Q

Hominoids

A

Apes.​

Gibbon, orangutan, gorilla, and chimpanzee.​

Larger brains than monkeys and lack tails.​

Paraphyletic group – some more closely related to hominids.​

Hominids.​

Humans.​

Soon after the gorilla lineage diverged, the common ancestor of all hominids split off from the chimpanzee line to begin the evolutionary journey leading to humans.

324
Q

Apes versus Hominids

A

The common ancestor of apes and hominids is thought to have been an arboreal climber​

Hominids became bipedal, walking upright.​

Apes evolved knuckle-walking.​

Differences related to bipedal locomotion​

Human vertebral column is more curved.​

Spinal cord exits from bottom of skull.​

Humans carry much of the body’s weight on the lower limbs.

325
Q

Early Hominins

A

Genus Homo​

3 to 7 species (depending how they are counted).​

Genus Australopithecus​

7 species.​

Older and smaller-brained.​

Several even older lineages​

In every case where the fossils allow a determination, the hominins are bipedal, the hallmark of hominin evolution​

326
Q

Australopithecines

A

Our knowledge is based on hundreds of fossils found in Africa​

Characteristics​

Weighed about 18 kg.​

About 1 m tall.​

Hominid dentition.​

Brains no larger than those of apes.​

Walked upright.

327
Q

Bipedalism

A

Seems to have evolved as australopithecines left forests for grasslands and open woodland​

African fossils demonstrate that bipedalism extended back 4 M Y A​

Substantial brain expansion, on the other hand, did not appear until about 2 M Y A​

Why bipedalism evolved is still a matter of controversy

328
Q

Genus Homo

A

The first humans evolved from australopithecine ancestors about 2 M Y A​

Thought to be Australopithecus afarensis ​

In the 1960s, hominid bones were found near stone tools in Africa​

Early human was called Homo habilis.​

Homo habilis closely resembled Australopithecus, but had larger brain

329
Q

Homo erectus

A

Sometimes considered to include Homo ergaster to be a single species​

More information about this species than we have about Homo habilis​

Larger than Homo habilis​

1.5 m tall.​

1000 cm^3 brain

Widespread and abundant in Africa, migrate to Asia and Europe​

Lived in tribes of 20 to 50 individuals, often in caves

330
Q

Homo floresiensis

A

In 2004, a new human species was discovered in the tiny Indonesian Island of Flores​

Age of H. floresiensis was 60 to 100,000 years ago​

H. floresiensis had a diminutive stature​

Coexisted with and preyed on a miniature species of elephant (now extinct)​

Believed to be more closely related to H. erectus than to H. sapiens

331
Q

H. floresiensis

A

Small size may be an example of “island dwarfism”

332
Q

Recently described Homo naledi

A

Possesses mix of features​

some typical of Homo - shape of the feet and teeth, small brain.​

Some more like australopithecines - curved fingers and shape of the legs for climbing.​

Doesn’t fit progression from Australopithecus to H. erectus to modern humans.​

May have coexisted with the modern humans.

333
Q

Modern Humans

A

Modern humans first appeared in Africa more than 500,000 years ago​

Three species are thought to have evolved​

Homo heidelbergensis (oldest).​

Coexisted with H. erectus.​

Homo neanderthalensis.​

Shorter and stockier than modern humans.​

Homo sapiens (“wise man”).​

Some lump all 3 into H. sapiens

334
Q

Neanderthals

A

Neanderthals, Homo neanderthalensis​

Made diverse tools.​

Took care of sick and buried dead.​

First evidence of symbolic thinking.​

They abruptly disappeared about 34,000 years ago.​

In some modern human populations, as much as 4% of D N A is of Neanderthal origin

335
Q

The Denisovans

A

Discovered in 2009 in a Siberian cave​

D N A did not match Neanderthal or modern human D N A​

Greater similarity to Neanderthal​

As much as 4% of the D N A in some populations in the South Pacific appear to have been derived from Denisovans​

Paleogenomics allows previously undiscovered species to be recognized

336
Q

Homo sapiens

A

Only surviving hominid​

Progressive increase in brain size​

Effective making and use of tools.​

Refined and extended conceptual thought.​

Use of symbolic language.​

Extensive cultural experience​

We change and mold our world rather than change evolutionarily in response to the environment.

337
Q

Human Races​

A

Human beings differentiated in their traits as they have spread throughout the world​

All humans are capable of mating with one another and producing fertile offspring​

Humans are visually oriented; consequently, we have relied on visual cues – primarily skin color – to define races​

Constant gene flow has prevented subspecies of humans from forming

338
Q

Groupings of Humans

A

Groupings based on overall genetic similarity are different from those based on skin color or other visual features

Biology (18 decks)

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