chapter 32 - overview of animal diversity

Question 1

animals are…

Answer 1

multicellular eukaryotes and heterotrophs that ingest food

Question 2

animal cells lack…

Answer 2

cell walls, cells supported by proteins such as collagen instead

Question 3

one of the defining characteristics of animals

Answer 3

nervous and muscle tissue

Question 4

reproduction and development overview

Answer 4

• most reproduce sexually
• diploid stage is usually dominant
• sperm fertilizes egg, zygote undergoes cell division called cleavage
• cleavage leads to formation of blastula
• blastula undergoes gastrulation

Question 5

what is a cleavage?

Answer 5

formed after zygote is formed and undergoes rapid cell division

Question 6

cleavage leads to the formation of…

Answer 6

a multicellular and hollow blastula

Question 7

gastrulation

Answer 7

bastula undergoes gastrulation, forming gastrula with different layers of embryonic tissues (germ layers)

Question 8

what is a larva?

Answer 8

sexually immature and morphologically distinct from the adult; eventually undergoes metamorphosis to become juvenile

Question 9

difference between juvenile and adult

Answer 9

juvenile looks similar but is not yet sexually mature

Question 10

developmental genes that regulate expression of other genes in most animals

Answer 10

Hox genes, regulate the development of body form + produce a wide range of animal morphology

Question 11

how many living animal species have been identified and how many are estimated to exist?

Answer 11

1.9 million living, 10-50 million estimated

Question 12

the common ancestor of all living animals likely lived around…

Answer 12

about 770 MYA

Question 13

who would the common ancestor resemble modern day?

Answer 13

modern choanoflagellates

Question 14

neoproterozoic era

Answer 14

(1 BYA - 541 MYA)
- early members of animal fossil record, include Ediacaran biota
- microscopic fossils of embryos found in neoproterozoic rocks
- evidence of predation found from Ediacaran period

Question 15

paleozoic era

Answer 15

(541-252 MYA)
- CAMRBIAN EXPLOSION: earliest fossil appearance of many major living animals
- most from c. explosion are bilaterians

Question 16

bilaterians traits

Answer 16

1. bilaterally symmetric form
2. complete digestive tract
3. one-way digestive system

Question 17

hypotheses regarding cause of Cambrian explosion and Ediacaran biota decline

Answer 17

1. new predator-prey relationship
2. rise in atmospheric O2
3. evolution of Hox gene complex and new microRNAs

Question 18

mesozoic era

Answer 18

(252-66 MYA)
- coral reefs emerged, imp marine ecol. niche
- dinosaurs dominant terrestrial vertebrates
- first mammals emerged, flowering plants + insects diversify

Question 19

cenozoic era

Answer 19

(66 MYA to present)
- beginning: mass extinctions for terrestrial and marine
- dinos and marine reptiles
- mammals increased in size, used vacated ecol. niches
- cooler global climate

Question 20

what is a body plan?

Answer 20

a set of morphological and developmental traits

Question 21

radial symmetry

Answer 21

have a top and bottom, but no front and back or left and right; often sessile or planktonic (flowerpot)

Question 22

bilateral symmetry

Answer 22

only one way for imaginary line to cut; two-sided shovel.
- dorsal: top, ventral: body
- anterior: front, posterior: back
- many have brain at anterior end
- more active and CNS

Question 23

ectoderm

Answer 23

germ layer covering embryo’s surface

Question 24

endoderm

Answer 24

innermost germ layer and lines the developing digestive tube called archenteron

Question 25

what do sponges and a few other groups lack?

Answer 25

true tissues

Question 26

diploblastic animals

Answer 26

only have ectoderm and endoderm, cnidarians and few others

Question 27

triploblastic animals

Answer 27

have an intermediate tissue layer called mesoderm

Question 28

all bilaterally symmetrical animals are...

Answer 28

triploblastic

Question 29

what is a true body cavity?

Answer 29

is called a coelom and is derived from mesoderm

Question 30

coelomates

Answer 30

animals that posses a true coelom

Question 31

pseudocoelomates

Answer 31

triploblastic animals that possess a pseudocoelom

Question 32

acoelomates

Answer 32

triploblastic animals that lack a body cavity

Question 33

functions of body cavity (coelome)

Answer 33

1. fluid provides cushion for organs 2. fluid acts like a skeleton against which muscles can work 3. enables internal organs to grow and move independently of the outer body wall.

Question 34

what is a grade?

Answer 34

a group whose members share key biological features; not necessarily a clade

Question 35

cleavage in protosomes

Answer 35

- spiral and determinate - fate of embryonic cells determined early

Question 36

cleavage in deuterostomes

Answer 36

- radial and indeterminate - each cell in early stage of cleavage retains capacity to develop into complete embroy - indeterminate cleavage makes identical twins and embryonic stem cells possible

Question 37

coelom formation protosome

Answer 37

spilling of solid masses of mesoderm forms coelom

Question 38

coelom formation deuterostome

Answer 38

the mesoderm buds from the wall of the archenteron to form the coelom

Question 39

blastospore

Answer 39

forms during gastrulation and connects the archenteron to the exterior of the gastrula

Question 40

blastospore protosome

Answer 40

becomes the mouth

Question 41

blastospore deuterostome

Answer 41

becomes the anus

Question 42

phylogenies are now primarily based on:

Answer 42

- Whole-genome analysis - Morphological traits - Ribosomal RNA (rRNA) genes - Hox genes - Protein-coding nuclear genes & mitochondrial genes

Question 43

important points about relationships among living animals

Answer 43

- all share a common ancestor - sponges are sister group to all other animals - eumetazoa, true animals, clade of animals w/ tissues - most animal phyla clade Bilateria - three major clades of bilaterian animals, all invertebrates, except Chordata which includes vertebrates

Question 44

what three clade are bilaterians divided into?

Answer 44

deterostomia, ecdysozoa, lophotrochozoa

Question 45

deuterostomia

Answer 45

includes hemichordates (acon worms), echinoderms (sea stars), and chordates - vertebrates and invertebrates

Question 46

ecdysozoa

Answer 46

- secrete external skeleton - shed exoskeleton as they grow (ecdysis) - all invertebrates

Question 47

lophotrochozoa

Answer 47

- all invertebrates - some have a feeding structure called a lophophore - others go through developmental stage called trochophore larva

Question 48

what are the two major character states in the phylogeny of living animals that separate organisms into different clades?

Answer 48

1. presence/absence of true tissues 2. type of symmetry