Animal Diversity

Question 1

how many living species of animals have been identified

Answer 1

1.3 million species

Question 2

when was the cambrian explosion

Answer 2

535-525 million years ago

Question 3

what is an animal

Answer 3

1. multi. cell euk
2. lack cell walls
3. cells held together by structural protein (collagen)
4. heterotrophs that ingest food

Question 4

what are tissues

Answer 4

group of cells with a common structure

Question 5

what tissues are unique to animals

Answer 5

nervous, muscle

Question 6

how do animals reproduce sexually?

Answer 6

diploid stage dominates life cycle

Question 7

cleavage

Answer 7

after fertilization, the zygote undergoes rapid cell division

Question 8

blastula

Answer 8

cleavage leads to the formation of this multicellular hollow thingy

Question 9

gastrula

Answer 9

different layers of embryonic tissues

Question 10

larva

Answer 10

• sexually immature
• morphologically distinct from adult
• eventually undergoes metamorphosis

Question 11

hox genes

Answer 11

regulate development of body form

Question 12

closest living relative of animals

Answer 12

protists

Question 13

choanoflagellates and sponge collar cells

Answer 13

nearly dientical

Question 14

evidence suggests what two are sister groups?

Answer 14

choanoflagellates and animals

Question 15

Ediacaran Biota

Answer 15

dates from 565 to 550 million years ago

Question 16

what happened during cambrian explosion

Answer 16

earliest fossil appearance of many major groups of living groups

Question 17

hypotheses regarding cause of cambrian explosion

Answer 17

1. new predatory-prey relationships
2. rise in atmospheric O2
3. evolution of hox gene cmoplex

Question 18

when did animals move onto land

Answer 18

460 million years

Question 19

when did vertebrates make the transition to land

Answer 19

365-370 million years ago

Question 20

what happened during the mesozoic era

Answer 20

• coral reefs emerged
• dinosaurs were the dominant terrestrial vertebrates
• first mammals
• flowering plants diversified

Question 21

cenozoic era

Answer 21

• mass extinction of terrestrial and marine animals
  ex.) large nonflying dinosaurs and marine reptiles

Question 22

how do zoologists categorize animals

Answer 22

body plan

Question 23

what symmetry animals have a central nervous sytem

Answer 23

bilateral animals

Question 24

tissues

Answer 24

collections of specialized cells isolated from other tissues by membranous layers

Question 25

what animals lack true tissues

Answer 25

sponges

Question 26

diploblasts

Answer 26

cnidarians, comb jellies

Question 27

ectoderm

Answer 27

germ layer covering the embryo’s surface

Question 28

endoderm

Answer 28

innermost germ layer

Question 29

in triploblasts, mesoderm…

Answer 29

form muscles and organs between endoderm and ectoderm

Question 29

protostome development

Answer 29

cleavage is spiral and determinate

Question 30

coelom

Answer 30

true body cavity derived from mesoderm

Question 31

deuterostome development

Answer 31

cleavage is radial and indeterminate

Question 32

points of agreement in animal debate

Answer 32

1. all animals share a common ancestor
2. sponges are basal
3. eumetazoa is a clade of animals with true tissues
4. most animals belong to bilateria
5. chordates = deuterostomia

Question 33

ecdysozoans

Answer 33

• nematoda and arthropoda
  (molt of exoskeleton)

Question 34

lophophore

Answer 34

• some lophotrochozoans have this feeding tube
• others= trochophore larva stage

Question 35

sponges are the base of what?

Answer 35

metazoans

Question 36

are acoelomates basal bilaterans?

Answer 36

molecular studies say so
—> flatworm-like ancestor