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1

What is a diploblast? a triploblast?

Dipoblast two germ layers (endoderm and mesoderm)
- Triploblast three germ layers (endoderm, mesoderm, ectoderm)
Ex. 2 layers cnidarian
Ex. 3 layers acoelomate platyhelminth
Ex. 3 layers coelomate echinoderm, mollusk, chordate

2

What is a coelom? What are the advantages to having a coelom?

coelom: fluid filled cavities between the gut and the body wall, found in most animals (within mesoderm)
-advantages shock absorber, container for circulating oxygen and nutrients, space for internal organs
-hydrostatic skeleton allows for movement

3

What is a protostome? A deuterostome? Give an example of an animal phylum that belongs to each group.

protostome is the first mouth (blastopore becomes mouth)
-formation of mouth before anus
-formation of coelom by splitting of a block of mesoderm
-ex. Arthropods, mollusks, annelids
- deuterostomes bilaterian animals (protostomes are also
bilaterians, and echinoderms sort of aren’t)
-formation of anus earlier than mouth
-formation of coelom by pinching off layers of mesoderm from the gut
-ex. Echinoderms and chordates

4

What is the function of ribosomes? Why is rRNA often used to assess phylogenetic relatedness among animal phyla?

large macromolecular machine that synthesizes proteins by
Using genetic information encoded in mRNA
-consists of 2 subunits, consisting of rRNA and proteins
-rRNA used to find relationships between phyla
-all animals possess rRNA because it is essential
-changes changes very slowly, can look at organisms that
Diverged long ago
-500+ million years
-more specialized DNA & RNA less useful for broad comparisons

5

In Fig. 33.2 (Phylogeny of Major Animal Phyla): Be able to explain why animals are monophyletic. Which phyla are deuterostomes? Which phyla have bilateral symmetry? Which phyla are triploblasts? Diploblasts? Which phyla have coeloms? What animal phylum is most closely related to Echinodermata? Most distantly related to Echinodermata? (We do not expect you to know this information without this phylogenetic tree as a reference)

- animals are monophyletic because the group “animals”
includes all descendants of a common ancestor
-sponges are paraphyletic and distantly related to other
animals
-sponges are paraphyletic because they include two group from the common ancestor of all animals, but not all animals

6

Name and describe the hypotheses that may explain the Cambrian explosion.

-Non-exclusive hypotheses
-major rise in sea level
-evolutionary arms race facilitated by higher levels of
Ca++ (used to build shell)
-increased oxygen (higher metabolism, larger size, shell)
-duplication of hox genes

7

What are the names of the two phyla discussed and what are some examples of each? (e.g. poriferans are sponges)

porifera: sponges
-Cnidaria: jellyfish, corals, sea anemones

8

What is the level of organization of sponges?

-cellular level of organization, all life processes occur in cells
-no true tissues or organs
-cells carry out all functions

9

What are the two sponge cell types that we discussed in lecture and what are their functions?

-choanocytes: collar cells, pumps water (100’s L/day)
-capture food particles
-amoebocyte: use pseudopodia (like amoeba) to move through gelatinous substance of sponge
-digesting, transporting, storing food
-totipotent: can differentiate into any type of sponge cells
-important in growth and healing

10

5. What happens after you put a sponge in a blender and strain the cells to dissociate them? Why is this possible?

-cells can come back together & form full sponge
-mix 2 species in blender  separate into 2 different sponges
-cell recognition & self organization
-kill outside cells
-immune cells

11

6. Be able to name the two adult body forms of cnidarians and describe the differences between the two.

-Polyp: cylinder w/ tentacles, mouth facing up attached to substrate, reproduce asexually
-Medusa: disk with tentacles mouth faces down, free swimming, reproduce sexually

12

7. Be able to describe the life cycle of a hydrozoan (e.g. slide 20) in general terms (e.g. Which body form reproduces asexually? Which reproduces sexually?).

- Medusa reproduce sexually and have separate sexes
- Polyp reproduce asexually

13

8. What type of symmetry do cnidarians possess? What is their level of organization?

- radial symmetry
- one opening: incomplete gut
- dipoblastic
- tissue level of organization (possess nervous and muscle tissue)

14

9. What is a cnidocyte? How does it work? What is a nematocyst?

-cnidocyte: stinger cells
-nematocyst: rapidly triggered by touch
-toxic barbs
-all cnidarias are predators

15

What are the three classes of Cnidaria that we discussed in lecture? (There is one other class which we didn’t discuss) Be able to give an example of each. Which of the two body forms of cnidarians are present and dominant in each of the classes?

-Hydrozoa: water animal (Portuguese man-of-war, Hydra) polyp main form (but also have medusa)
-Scyphozoa: true jellies medusa main form (but also have polyps)
-Anthozoa: corals and sea anemones polyp only (no medusa)

16

11. What is the genus name of the dinoflagellate symbiont of corals? What type of relationship does it have with coral? Justify your answer.

Symbiodium, mutualism – coral receives sugars, dinoflagellates receive shelter

17

What is coral bleaching? What causes it to occur?

-coral bleaching occurs when increased temperature (mostly), increased light, or pollution causes corals to lose their Symbiodinium symbionts (dinoflagellates)
-when coral loses its color and becomes white

18

What are the advantages of being as flat as a flatworm (Platyhelminthes)?

-high surface are to volume ratio
-need no specialized circulatory or respiratory system
-bilateral- have cephalization (heads)
-tripoblastic but acoelomate
-free living or parasitic
[not advantages of flat, but are flatworm features]

19

What worm causes Schistosomiasis and how do you catch it? What are the 2 hosts of Schistosoma? To which class does Schistosoma belong?

- Trematoda: the flukes
- Get it from water marine or fresh
- All trematodes have 2 hosts
o Produce asexually in snails
o Reproduce sexually in humans
[these hosts are specific to Schistosoma, although most trematodes do have mollusk and vertebrate hosts]

20

15. What is the cause of the large belly of people with Schistosomiasis?

caused by scar tissue from trapped eggs in intestines, bladder, and liver

21

16. What are the names of the 3 major classes of Platyhelminthes? Be able to give common names or an example of each. Which of the classes contain only parasites?

-Tubellaria: Dugesia, planarians (most predators, some parasitic)
-Trematoda: flukes, Schitosoma (all parasitic)
-Cestoda: tapeworms (all parasitic)

22

Why would a parasite want to take over its host behavior or change its appearance?

to move host

23

Where do adult tapeworms live? What structure do they use to stay attached?

-live in the guts of vertebrates
-attach w/ scolex (hooks & suckers)

24

What are four characteristics of the body plan of a mollusk. What is the function of each?

-radula: tiny teeth for feeding
-shell: protects body
-Mantle: secretes shell
-foot: muscular for movement

25

20. What are the names of the 3 major classes of Mollusca? Be able to give some examples of each.

-Gastropoda: snails, slugs, sea slugs
-Bivalvia: clams, oysters, mussels, scallops
-Cephalopoda: octopuses, squid, cuttlefish

26

What is the most endangered group of animals in North America? Why are they endangered?

- Freshwater mussels are the most endangered group of animal in NA. Endangered because of:
- Water pollution
- Impoundment (damming) of rivers changes habitat
- Invasive species (e.g. zebra mussel)
- FW mussel larvae are parasitic on specific fishes, which
are also endangered

27

What characteristic of octopus led to strong natural selection for high intelligence? What other defense mechanisms to octopus possess?

- lack of shell probably led to selection for intelligence
-10 lobes
-most developed brain
-camouflage, beak, ink

28

23. On the slide about learning by Octopus vulgaris, be able to explain the graph. What does the graph indicate about how Octopus vulgaris learns?

they just have to see someone do it
-or they can be trained

29

24. What are the four main types of learning we discussed? Can you differentiate them?

-habituation: loss of responsiveness (used to)
-spatial learning:memory
-associative learning or classical conditioning: learning
-imprinting: recognize

30

What is segmentation? What are the benefits of possessing segmentation? What three phyla possess segmentation?

- Separated into different parts
- Conserve energy, makes injuries non-fatal
- Asexual reproduction
- High degree of specialization possible
- Allows for precise movement