Lecture 18 Introduction to Animals

Question 1

which clade are fungi and animals in?

Answer 1

opisthokonts

Question 2

what are animals?

Answer 2

multicellular, heterotrophic eukaryotes (with some exceptions)

Question 3

how are animal bodies held together?

Answer 3

extracellular structural proteins

Question 4

what are the specialized cells that are not found in other multicellular organisms? (2)

Answer 4

• nervous tissues

- muscle tissues

Question 5

what are tissues?

Answer 5

groups of cells that have a common structure, fxn or both, isolated from other tissues by membranous layers

Question 6

how do animals get nutrition?

Answer 6

chemoheterotrophs

- ingest food and digest within bodies

Question 7

how do most animals reproduce, and what ploidy stage usually dominates?

Answer 7

• reproduce sexually

- usually diploid dominates life cycle

Question 8

define motile

Answer 8

capable of moving the entire multicellular body in at least one stage in the life cycle

Question 9

what is the homeobox?

Answer 9

regulatory genes that produce proteins that can turn other genes on/off (NOT unique to animals)

Question 10

what are hox genes?

Answer 10

genes that regulate the development of body form

Question 11

what is cleavage?

Answer 11

when a diploid zygote undergoes a number of mitotic rapid cell divisions

Question 12

what does the cleavage of the diploid zygote lead to?

Answer 12

a multicellular hollow blastula which is exclusive to animals

Question 13

what is the internal cavity of the blastula called?

Answer 13

blastocoel

Question 14

what does the blastula undergo, and what does it form?

Answer 14

blastula undergoes gastrulation forming the gastrula within different layers of gastrula tissues

Question 15

how many layers of cells does the gastrula have?

Answer 15

2

• ectoderm
• endoderm

Question 16

what are the two types of development?

Answer 16

• direct and indirect

Question 17

what is direct development?

Answer 17

• embryo continues on towards animal form

Question 18

what is indirect development

Answer 18

• there are intervening stages (ex larvae) whose morphology and behaviour differs greatly from sexually mature adult stage

Question 19

what are the two traditional divisions of animals?

Answer 19

• without true tissues

- with true tissues - eumetazoa

Question 20

what are the four body plans that animals are categorized by?

Answer 20

• symmetry
• layers of tissue
• body cavities
• embryonic development

Question 21

what is radical symmetry?

Answer 21

no front/back/left/right

- can be divided into many planes of symmetry

Question 22

what is bilateral symmetry?

Answer 22

only one plane of symmetry - two sided

- most animals

Question 23

what sides does a bilateral animal have?

Answer 23

right and left
dorsal (top) and ventral (bottom)
anterior and posterior

Question 24

what is cephalization?

Answer 24

development of a head

Question 25

what are the 3 germ layers that give rise to tissues and organs of animal embryos?

Answer 25

• ectoderm
• mesoderm
• endoderm

Question 26

what is the ectoderm?

Answer 26

outer layer that forms skin and nerves

Question 27

what is the endoderm?

Answer 27

intervening layer forming muscle and other organs

Question 28

what is the endoderm?

Answer 28

inner layer which lines developing digestive tube: archenteron– digestive tract, gut

Question 29

what is the archenteron

Answer 29

archenteron– digestive tract, gut

Question 30

what are diploblastic animals?

Answer 30

animals with 2 embryonic cell layers

• endo and ecto
  ex: radiata cnidarians and comb jellies

Question 31

what are triploblastic animals?

Answer 31

animals with 3 embryonic cell layers

• endo, meso, ecto
  ex: flatworms, anthropods, vertebrates, etc

Question 32

what is a true body cavity?

Answer 32

coelem, which is derived from the mesoderm

Question 33

what is a coelomate?

Answer 33

animal that possesses a true ceolem

Question 34

what is a pseudocoelem?

Answer 34

a body cavity derived from mesoderm and endoderm

Question 35

what are pseudocoelomates?

Answer 35

animal that possesses a pseudocoelom

Question 36

what are acoelomates?

Answer 36

animals that lack a body cavity

Question 37

what are coelomates and pseudocoelomates if they are not clades?

Answer 37

grades: group whose members share key biological features

Question 38

what are the fxns of coeloms and pseudocoeloms?

Answer 38

• cushions internal body organs from blows to outside body
• allows internal organs to shift without deforming outside of the body
• fluid filled cavity can be used as a hydrostatic skeleton by tensing muscles around an incompressible fluid

Question 39

what was the first split?

Answer 39

• based on the presence of true tissues : Eumetazoa clade

Question 40

what was the second split?

Answer 40

• bilateral splite : Bilatera clade

Question 41

what was the third split?

Answer 41

• embryonic development

protosome vs deutersome

Question 42

how does the protosome and deutersome differ?

Answer 42

• embryo cleavage
• coelom formation
• fate of blastopore

Question 43

what is the cleavage of protosomes vs deutersomes?

Answer 43

Protosomes: spiral and determinate

Deutersomes: radial and indeterminate

Question 44

what does determinate mean?

Answer 44

each new cell is destined to form some part of the later embryo – removal of some cells results in embryo missing organs

Question 45

what does indeterminate mean?

Answer 45

each cell in early stages of cleavage retains capacity to develop into a complete emrbyo

Question 46

what is the coelom formation of protosomes vs deutersomes?

Answer 46

Protosomes: splitting of solid masses of mesoderm forms coelom

Deutersomes: mesoderm buds from wall of archenteron to form coelom

Question 47

fate of the blastospore protosomes vs deutersomes?

Answer 47

Protosomes: blastopore becomes mouth

Deutersomes: blastopore becomes anus