Lab Exam 3 - Ch. 33, Ch. 34, etc. Flashcards
When was the Cambrian explosion?
550 million years ago
How many species are alive on our planet?
Between 8 million and 50 million
How many species have been described and named?
About 1.4 million
What were the ancestors to animals?
Single-celled protists
What are key traits that animals share?
- eukaryotes
- multicellular with no cell walls but extensive extracellular matrix
- heterotrphs (obtain carbon from other sources, not by absorbing)
- move under their own power at some point in their life cycle
- OTHER THAN SPONGES – have neurons and muscle cells
How do multicellular fungi and animals compare in digestion?
Both are multicellular heterotrophs that break down and absorb nutrients.
But animals are the only multicellular organisms that ingest their food first before they digest it.
Describe animals’ neutral systems and its effect on movement
Neutrons connect to each other, forming a nervous system; some neurons connect to muscle cells. Muscles and neurons allow a large, multicellular body to move efficiently.
This makes animals outstanding eaters.
How many phyla of animals are there?
30-35 phyla
What types of data do evolutionary biologists study?
Fossils
comparative morphology
comparative genomics
Are animals paraphyletic, polyphyletic, or monophyletic?
Animals are monophyletic. All animals share a common ancestor.
Where did multicellularity originate?
Probably in a sponge-like common ancestor.
When did the first sponges appear?
600 million years ago.
Sponges are sessile. What does that mean?
Adults live permanently attached to a substrate
How do sponges feed?
They beat flagella to create water currents bringing organic debris toward feeding cells called choanocytes. The choanocytes trap food and ingest it.
Do sponges have epithelium?
SOME sponges have epithelium – tightly joined cell layers that cover the interior and exterior surface of the animal.
How are sponges distinguished?
size, shape, composition, type of spicules (stiff spikes of silica or calcium carbonate)
Do sponges have complex tissues?
No
Most animals are divided into two major groups based on the number of embryonic tissue layers they have. How?
Diploblasts – animals whose embryos have two types of tissues
Triploblasts – animals whose embryos have three types of tissue
How are embryonic tissues organized?
In layers called germ layers
What are the germ layers called in diploblasts?
ectoderm and endoderm
What are the germ layers called in a triploblast?
Ectoderm, mesodrm, endoderm
How do embryonic tissues develop into adult tissues in triploblasts?
Ectoderm produces covering of the animal, endoderm generates digestive track. Mesoderm gives all tissues in between.
ectoderm –> skin and nervous system
endoderm –> lining of the digestive tract
mesoderm –> circulatory system, muscle, and internal structures like bone and most organs
Which two groups of animals traditionally have been recognized as diploblasts?
Ctenophora (comb jellies) and Cnidaria (jellyfish, corals, sea pens, hydra, anemones).
Recent discovery: Some cnidarians have true mesoderm, though.
Which evolved first: Multicellularity or diploblasty?
Multicellularity and then diploblasty.
What animals have radial symmetry?
cenophores, cnidarians, and some sponges
radial symmetry evolved independently in echinoderms
What are the two types of symmetry?
radial symmetry and bilateral symmetry
Describe the three nervous system organization schemes
- Sponges – lack both nerve cells and symmetry
- Ctenophores and cnidarians have nerve cells that are organized into a nerve net. Generally radially symmetric
- All other animals have central nervous system; some neurons clustered into tracks/cords projected through the body; others are clustered in masses called ganglia
What is cephalization?
the evolution of a head, or anterior region, where structures for feeding/sensing/processing are concentrated.
What is the basic bilaterian body shape?
A tube within a tube. The inner tube is the individual’s gut: mouth on one end, anus on the other.
The outer tube is the nervous system and skin.
The mesoderm in between forms organs.
What is the coelom?
A fluid-filled cavity between the inner and outer tubes. It’s a space for the circulation of oxygen and nutrients. Allows internal organs to move independently of each other.
Where, phylogenetically, did the coelom arise?
In the common ancestor of protostomes and deuterostomes.
Characterize animals by their coeloms
Coelomates have a cavity fully lined with mesoderm
Acoelomates have no coelom
Pseudocoelomates have a cavity partially lined with mesoderm.
What are the two major groups within bilaterian coelomates?
protostomes – mouth develops before anus and blocks of mesoderm hollow out to form coelom
deuterostomes – anus develops before mouth and pockets of mesoderm pinch off to form coelom
What are the two main groups of protostomes?
Lophotrochozoa (mollusks, annelids, flatworms, rotifers)
Ecdysozoa (arthropods, nematoads)
Define segmentation
appearance of repeated body structures
Describe the Cnidaria life cycle
polyp form includes feeding polyps and reproducive polyp. (2n)
Mitosis –> Medusa form (2n)
Meiosis –> egg and sperm (n) join to form zygote (2n)
zygote becomes larva (2n)
larva becomes polyp form (2n)
What distinguishes protostomes from deuterostomes?
- during gastrulation, the initial pore that forms becomes the mouth rather than the anus
- If a coelom forms, it forms from cavities that arise within blocks of mesoderm rather than as mesoderm pockets pinching off the gut.
What are the three morphological traits that define the lineage of lophotrochozoans?
- a feeding structure called a lphophore
- a type of larva called a trochophore
- a spiral pattern of cleavage in embryos
Describe mollusk anatomy
lophotrochozoan
three major components:
- foot - large muscle located at the base of the animal and usually used in movement
- visceral mass - the region containing most of the main internal organs and the external gill
- the mantle - the outgrowth of the body wall tat covers the visceral mass
What lineages came from mollusks?
bivalves (clams and mussels),
gastropods (slugs and sails),
chitons (mollusks with dorsal shells made of plates) and
cephalopods (squid and octopuses)
What are the three key features of the arthropod body plan?
segmented body, chitin exoskeleton, jointed appendages
what are the two types of arthropod metamorphosis?
hemimetabolous metamorphosis - nymphs look like mini adults
holometabolous metamorphosis - distinct larval stage
What is the difference between millipedes and centipedes?
m - decomposers, can have over 190 sections
c - poisonous hunters, typically have <30 segments
Describe the characteristics of phylum porifera
- sponges
- asymmetrical mostly
- sessile (benthic) adults; motile larvae
- internal skeleton supported by spongin (protein) and spicules (stiff silica/cac3 spikes)
- mostly asexual reproduction
How do sponges feed?
Water flows into sponge through ositum
gets to interior (spongocoel)
feeding cells eat (choanocyte)
water goes out of sponge through osculum
Describe the characteristics of cnidaria
jellyfish, sea anemones, hydra, corals
radial symmetry
diploblastic
have cnidocytes – stinging cells that help capture prey
three life cycle stages: polyp, medusa, larva
What are the three classes of cnidaria?
anthozoa (corals, sea anemones)
- polyp dominant
- hard exoskeleton of CaCO3
- Form coral reefs
Scyphozoa (true jellies)
- medusa dominant)
hydrozoa
- alternate between polyp and medusa
describe the anatomy of phylum platyhelminthes
flatworms
eyespots, auricle, pharynx extended through mouth, gastrovascular cavity
Describe tapeworm feeding
tapeworms are endoparasites. their hooks and sucker attach to the gut wall. They have many proglottids (segments)
describe the anatomy of phylum nematoda
they have a hydrostatic skeleton
Identif the chaetae, clitellum, and typhlosole of an earthworm (annelida)
characterize the mollusk’s internal anatomy. Find:
umbo, mantle, anterior, posterior, adductor muscle, excurrent siphon, incurrent siphon, foot, gill
how many antennae to crustacea have?
two pairs
Where do fossils form?
Sedimentary rock
What are the three types of fossils
remains, impressions, trace fossils
How are fossils dated?
relative dating and absolute dating
What is the principle of superposition and who expressed it?
Nicholas Steno: In layers of sediment, oldest layers are at the bottom and get younger as you go up.
What is an index fossil
A fossil species that is abundant and has a wide geographic distribution but only for a short time. That way, have an index.
How is absolute dating done
Radiometric dating uses known decay rates of radiactive isotopes to determine age of rocks. Uses half life.
What are the important dates in the geologic record?
Origin of earth = 4,600 mya
Oldest fossils = 3,500 mya (prokaryotic, from stromatolites)
Phanerozoic Eon (start of Paleozoic Era) = 542 mya
Cambrian explosion = 525 mya
Paleozoic/Mesozoic Boundary = 251 mya (end-Permian mass extinction)
Mesozoic/Cenozoic Boundary = 65.5 mya (End-cretaceous mass extinction)
What is this?
Scypha, of phylum porifera
What is this and what is it made of?
skeleton of a porifera (sponge) . it is made of silica
what is this and what is it made out of?
a sponge (of phylum porifera) made of spongin
ID
water goes in through ostia with other stuff; all goes into spongocoel (lined by choanocyte cells) and out through osculum. Choanocytes have flagella that beat and actually move the water.
ID.
hydra (of phylum cnidaria)
What are the functions of tentacles in hydra?
stinging – they have specialized stinging cells called cnidocytes
locomotion?
ID
hydra
ID on a hydra:
gastrovascular cavity
tentacles
mouth
cnidocytes
cell layers: epiderms & gastrodermis
What are Scyphozoa?
True jellyfishes
What are anthozoa?
corals and sea anemones
Recite the lab 1 phyla
- porifera (sponges)
- cnidaria
- hydra
- scyphozoa (true jellyfish)
- anthozoa (coral, sea anemone)
Recite the lab 2 phyla
- platyhelminthes (flatworms)
- annelida (earthworms, marine worms, leeches)
- mollusca
- bivalvia (scallops, clams, oysters)
- gastropoda (snails, slugs)
- cephalopoda (octopuses, squid, cuttlefish, chambered nautilus)
Do cnidarians exhibit cephalization?
No. They have a nerve net, not a concentrated brain.
characterize the body plans of platyhelminthes, annelida, and mollusca
triploblastic
bilaterally symmetrical
What is a hydrostatic skeleton?
the coelom is a pressurized water body cavity that allows muscle contraction to happen
Are flatworms coelomates?
No, flatworms (platyhelminthes) are acoelomates. Skin (from ectoderm), muscles/organs (from mesoderm), and gut (from endoderm) without a cavity for water.
ID
planarian, of phylum platyhelminthes
ID on planaria:
head, eyespots
auricles (what is the function?)
gastrovascular cavity
pharynx (function?)
auricles are chemosensory structures
pharynx connects the mouth to the gastrovascular cavity
ID
tapeworm, of phylum platyhelminthes
ID scolex and proglottid on the relevant organism
on tapeworm (platyhelminthes) – scolex is the head wit hooks and suckers. proglottids are th esegments of the tapeworm’s body. matured proglottids are filled with fertilized eggs; they break off from the posterior end of the worm and go with host waste to continue life cycle.
Do flatworms have incomplete or complete digestive systems?
Incomplete digestive systems.
Are cnidarians and sponges autotrophs or heterotrophs? chemotrophs?
chemoheterotrophs – they can’t photosynthesize and they ingest carbon from other sources.
What are examples of annelida?
segmented worms: earthworms, marine worms, leeches
what are the characteristics of annelida?
segmentation
coelomates (hydrostatic skeleton)
first body segment is called the prostomium – above the mouth and has sensory structures
bristle-like chaetae that come from the segments and function in movement
Describe earthworms’ feeding patterns
deposit feeders
describe earthworms’ special anatomical structures
clitellum is the smooth saddle-like structure near the middle of the body. functions in reproduction.
does earthworms exhibit segmentation and cephalization?
yes to segmentation
yes to cephalization
for earthworm, ID:
circular muscles, longitudinal muscles
tube within a tube
typhlosole
typhlosole is the internal fold inside the intestinal space. it increases the surface area of the digsetive tract.
Marine worm characteristics:
segmentation
many chaetae (for locomotion in water)
cephalization
ID
leech
they use suckers/hooks to extract food
yes they exhibit segmentation
Do mollusks have a coelom? What kind of digestive system do they have?
Yes coelom.
complete digestive system.
What are mollusk exoskeletons made of and where do they come from?
calcium carbonate
secreted from mantle, the thin tissue layer on the outside
What is in class gastropoda?
snails and slugs.
describe the feeding structure of gastropoda. function?
also ID foot and exoskeleton
radula – located inside the mouth and covered with small, chitinous teeth.
scrape algae or microorganisms off of a substrate; some predators.
how many shells do gastropods have?
one shell
ID main bivalve anatomical features
no cephalization
incurrent and excurrent siphons that generate flow over gills – gills trap small food particles from water.
two shells connected at the hinge.
umbo is thick part of hinge. orient with umbo on left.
mantle is tissue layer just under shell
foot is the big muscle
incurrent (bottom) to gills to excurrent (top) siphon on right side
adductor muscles above gills
ID
chambered nautilus
What are the chambers in a chambered nautilus used for?
buoyancy
Describe the shells of squis and octopi
squid: thin internal
octopus: lost completely
Do cephalopods exhibit cephalization
yes
What are the lab three phyla?
- nematoda (segmented worms like earthworms, marine worms, leeches)
- Arthropoda (insects, spiders, crustaceans, etc.)
- trilobitomorpha - trilobites
- cheliceriformes - horseshoe “crabs”, spiders, mites, scorpions, ticks
- crustacea - lobsters, crabs, etc.
- myriapoda - millipedes, centipedes
- hexapoda - insects
describe the characteristics of nematodes
round worms. pseudocoelomate. some are free living and others are parasites. Found in pork.
describe nematodes that live in mammal muscle tissue
trichinella. larvae are encysted in muscle. causes trichinosis.
What does arthropod mean?
jointed foot
what characteristics unite all arthropods
jointed feet
chitin exoskeleton with calcium carbonate
high degree of segmentation
why is segmentation tied to evolutionary success?
segmentation provides “raw material” for natural selection to mold into a diversity of shapes/functiosn to exploit many different lifestyles.
how many pairs of antennae do crustaceans have?
two pairs
how many pairs of walking legs do crayfish have?
five pairs
Compare and contrast centipedes and millipedes
centipedes: predatory, fast, one pair of legs per segment
millipedes: scavengers, slow, two pairs of leg per segment
How do hexapods breathe?
through pores and the side of the abdomen called spiracles (NOT spicules like the things that are on sponges)
Very similar to stomata in plants: pores that can open and close to regulate gas exchange
