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
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)
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
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)
ID
hydra
ID on a hydra:
gastrovascular cavity
tentacles
mouth
cnidocytes
cell layers: epiderms & gastrodermis
What are anthozoa?
corals and sea anemones
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
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
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.
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
describe nematodes that live in mammal muscle tissue
trichinella. larvae are encysted in muscle. causes trichinosis.
