Intro to Animal Diversity Lecture 10

Question 1

List several reasons why biologists study animals.

Answer 1

1) because they impact us
2) Because they are fascinating…and apparently funny.
3) Animals play important roles in the food chain.
4) Animals are species rich and morphologically diverse.
5) Humans are animals!

Question 2

List at least five characteristics that define animals.

Answer 2

1. are multicellular
2. move on their own (at some point in their life cycle)
3. ingest their food (for the most part)
4. lack cells walls, but have an extensive and supportive extracellular matrix
5. are the only lineage with members that have muscle and nervous tissue
6. can reproduce sexually and asexually, but do not exhibit alternation of generations
7. have adults that are diploid, with the only haploid cells being the gametes produced during sexual reproduction (most species)

Question 3

Outline the major groups of the animal kingdom based on embryonic germ layers, symmetry, the presence or absence and type of coelom, and protostome or deuterostome development.

Answer 3

NOTES

Question 4

Distinguish between diploblastic and triploblastic

Answer 4

• Animals who have two different tissue (germ) layers are called diploblasts.
• Animals who have three different tissue (germ) layers are called triploblasts.

Question 5

Distinguish between asymmetry, radial symmetry, and bilateral symmetry and state how animal symmetry often matches the animal’s way of life.

Answer 5

asymmetric- no symmetry
radial symetry- can be cut into many different symmetrtic ways
bilateral symmetry can only be cut one way

Symmetry of an animal typically suits its lifestyle.
• Many radial animals are sessile or planktonic
• Bilatarians tend to actively move from place to place and exhibit more complex movements in doing so.

Question 6

Explain the advantage of bilateral symmetry and cephalization.

Answer 6

Bilaterians have a central nervous system
• Some neurons clustered into one or more tracts or cords that project through body; some neurons clustered into ganglia. Advantage can help them guide to prey

Question 7

Explain the association between symmetry and nervous systems.

Answer 7

Association between symmetry + nervous system
• Sponges lack neurons
• Cnidarians have a nerve net
• Bilaterians have a central nervous system

Question 8

Distinguish between acoelomate, pseudocoelomate, and coelomate.

Answer 8

Acoelomates: no coelom
• Pseudocoelomates: the cavity forms
between the endoderm and mesoderm.
• Coelomates: cavity develops within,
and is completely lined by, the mesoderm.
• This means that muscle and blood vessels form on both sides of the cavity.

Question 9

State the functions of a body cavity.

Answer 9

Acts as a “container ” for the internal organs.
• Suspends organs in fluid
• Provides cushioning, prevents injury
• Allows for free movement of organs
• Also used to circulate O2, dissolved nutrients.
• Serves as a hydrostatic skeleton that facilitates movement in some animals that don’t have
limbs.

Question 10

Compare the developmental differences between protostomes and deuterostomes, including:

a. pattern of cleavage
b. outcome of gastrulation
c. coelom formation

Answer 10

1) cleavage
Protosomes 8 cell stage spiral and determinate
deuterostomes 8 cell stage radial and indeterminate

2) gastrulation:
protosomes: mouth first
deuterostomes: butt first

3) coelom formation:
Protosomes: block of solid mesoderm slits to form coelom
deuterostomes: mesoderm pockets pinch off to form coelom

Question 11

Briefly describe the origin of animals from a choanoflaggelate-like ancestor
and state the evidence that supports this theory.

Answer 11

• Choanoflagellates and the collar cells (or choanocytes) of sponges are morphologically and functionally (almost) identical.
• Large choanoflagellate colony turned inside out would resemble a sponge.
• Similar collar cells have been found in other animals, but never in plants, fungi, or non-choanoflagellate protists.

Question 12

Define “segmentation”.

Answer 12

Segmentation occurs when a body is divided

into a series of repeated features.

Question 13

Distinguish between the ecdysozoans and the lophotrochozoans.

Answer 13

Protosotoma further divided into: 
• Ectdysozoa 
• Grow by shedding an external (exo) skeleton
(i.e. molting) 
• Lophotrochozoa 
• Grow continuously without molting.

Question 14

Describe how animals differ from both plants and fungi in how they obtain food.

Answer 14

Ingest their food

Question 15

Describe the 4 general ways in which animals obtain food, with specific examples.

Answer 15

Suspension feeders: capture food by filtering particles out of water or air ex. whales

Deposit feeders: animals that eat their way through a substrate ex. Earthworms

Fluid-feeders: Suck or lick up liquids like nectar, plant sap, blood, or fruit juices. ex, mosquitoes

Food-mass feeders take chunks of food into their mouths ex. lions

Question 16

Distinguish between herbivores, carnivores, detritivores, and omnivores.

Answer 16

• Herbivores eat plants and algae.
• Carnivores eat animals.
• Detritivores eat dead or decaying matter.
• Omnivores eat both plants and animals.

Question 17

Distinguish between predators and parasites

Answer 17

• Predators: kill other organisms.
• Parasites: generally much smaller than their prey and often harvest nutrients from their prey without actually killing them.

Question 18

Distinguish between endoparasite and ectoparasite.

Answer 18

• Endoparasites live inside their hosts.
• Often wormlike in shape and live in the gut of their host.
• Ectoparasites live outside their hosts
• Usually have grasping mouth parts that pierce the host’s skin and suck the nutrient-rich fluid from inside

Question 19

List three structures that power animal movement.

Answer 19

Cilia and flagella, parapodia, tube feet, muscles that compress a hydrostatic skeleton, muscles that attach to a hard skeleton

Question 20

State the advantage of jointed limbs.

Answer 20

allow for fast coordinated movements

Question 21

Briefly compare reproduction in animals to that of plants and fungi.

Answer 21

??

Question 22

Distinguish between viviparous, oviparous, and ovoviviparous.

Answer 22

• Viviparous animals give birth to live young.
• Oviparous animals lay fertilized eggs.
• Ovoviviparous animals retain eggs that are nourished by a yolk inside the egg, rather than by nutrients transferred from the mother as in viviparous species

Question 23

Distinguish between internal and external fertilization.

Answer 23

1) External:
common in aquatic species

2) Internal :
• Male can insert sperm directly into 
female. 
• Female can pick up packets of sperm 
and insert them into herself. 
• Female can insert eggs into male.