Chapter 32: Animal Diversity

Question 1

Most diverse animal group

Answer 1

terrestrial arthropods

Question 2

animal

Answer 2

multicellular, heterotrophic eukaryotes with tissues that develop from embryonic layers

Question 3

collagen

Answer 3

structural protein that supports cell walls

Question 4

muscle cells

Answer 4

contractile cells to generate motion

Question 5

nerve cells

Answer 5

conduct electrical impulses

Question 6

methods of asexual reproduction

Answer 6

budding, fission, parthenogenesis (virgin birth)

Question 7

dominant life cycle stage

Answer 7

diploid stage is dominant

Question 8

sexual reproduction

Answer 8

typically a small flagellated sperm fertilizes a large egg; diploid adults produce haploid gametes

Question 9

zygote

Answer 9

fertilized egg that develops into gastrula

Question 10

cleavage

Answer 10

cell division without growth

Question 11

blastula

Answer 11

hollow ball of cells with an internal cavity (blastocoel)

Question 12

gastrulation

Answer 12

invagination of blastopore to form the beginning of the gut (different in sponges)

Question 13

sponge cell characteristics

Answer 13

lack tissues; cells can de-differentiate into other cell types

Question 14

archenteron

Answer 14

formed by invagination; gives rise to the gut

Question 15

endoderm

Answer 15

tissue lining gut

Question 16

ectoderm

Answer 16

outer layer of cells; skin and nervous system

Question 17

diploblasts

Answer 17

only two tissue types; “fancy gastrula”

Question 18

triploblasts

Answer 18

have a third germ layer known as the mesoderm that forms all other organs between gut and outer surface

Question 19

direct development

Answer 19

offspring looks like a little version of the parent

Question 20

indirect development

Answer 20

young offspring (larvae) are morphologically/ecologically different than the adult

Question 21

clade that animals belong to

Answer 21

opisthokonts (like fungi)

Question 22

closest relatives to animals

Answer 22

choanoflagellata: similar feeding cell type; analysis of DNA sequence data

Question 23

neoproterozoic era

Answer 23

era in which animals arise

Question 24

ediacaran biota

Answer 24

earliest large animal fossils

Question 25

cambrian explosion

Answer 25

appearance in the fossil record of most animal phyla

Question 26

bilaterians

Answer 26

most of the fossils from the cambrian explosion; bilaterally symmetric form with complete digestive tract

Question 27

mesozoic era

Answer 27

age of dinosaurs; bounce back of animals after extinction

Question 28

end-cretaceous extinction

Answer 28

wiped our dinosaurs and other groups

Question 29

cenozoic era

Answer 29

modern era; diversification of large mammals

Question 30

animal body plans

Answer 30

specific and conserved; development under control of Hox genes. 3 aspects: symmetry, tissue organization, and body cavities

Question 31

sponge symmetry

Answer 31

asymmetrical

Question 32

sea anemone symmetry

Answer 32

radially symmetrical

Question 33

symmetry of most animals

Answer 33

bilateral symmetry; dorsal, ventral, anterior, posterior

Question 34

cephalization

Answer 34

having a front end (head); typical of animals that move under own power

Question 35

coelom

Answer 35

fluid-filled body cavity

Question 36

coelomates

Answer 36

body cavity lined with mesoderm

Question 37

pseudocoelmates

Answer 37

not completely lined with mesoderm

Question 38

acoelomates

Answer 38

lack a body cavity

Question 39

hydrostatic skeleton

Answer 39

fluid-filled body cavity serves as a hydrostatic skeleton to antagonize muscles

Question 40

protosomes

Answer 40

solid masses of mesoderm form; expand to filled blastocoel. determinate spiral cleavage; blastopore becomes the mouth

Question 41

deuterostomes

Answer 41

mesoderm buds off endoderm of archenteron; indeterminate radial cleavage; blastopore becomes anus

Question 42

5 important points about relationships among living animals

Answer 42

1. share a common ancestor 2. sponges are sister group to all other animals 3. eumetazoa is a clade of animals with tissue (all except sponges) 4. most animal phyla belong to the bilateria clade 5. 3 major clades of bilaterian animals: deuterostomia, ecdysozoa, lophotrochozoa

Question 43

deuterostomia diversity

Answer 43

invertebrates or vertebrates; includes hemichordates, echinoderms, and chordates

Question 44

ecdysozoa

Answer 44

all invertebrates; includes nematodes and arthropods; secrete an exoskeleton for growth (ecdysis)

Question 45

lophotrochozoa

Answer 45

all invertebrates; named for features: lophophore and trochophore larvae

Question 46

lophophore

Answer 46

crown of ciliated tentacles used for feeding; ie. ectoprocts

Question 47

trochophore larva

Answer 47

developmental stage; ie. mollusks and annelids

Question 48

porifera

Answer 48

sponges

Question 49

cnidaria

Answer 49

jellyfish, sea anemones, coral

Question 50

bilateria

Answer 50

animals with bilateral body symmetry