Lecture 18 Introduction to Animals Flashcards
which clade are fungi and animals in?
opisthokonts
what are animals?
multicellular, heterotrophic eukaryotes (with some exceptions)
how are animal bodies held together?
extracellular structural proteins
what are the specialized cells that are not found in other multicellular organisms? (2)
- nervous tissues
- muscle tissues
what are tissues?
groups of cells that have a common structure, fxn or both, isolated from other tissues by membranous layers
how do animals get nutrition?
chemoheterotrophs
- ingest food and digest within bodies
how do most animals reproduce, and what ploidy stage usually dominates?
- reproduce sexually
- usually diploid dominates life cycle
define motile
capable of moving the entire multicellular body in at least one stage in the life cycle
what is the homeobox?
regulatory genes that produce proteins that can turn other genes on/off (NOT unique to animals)
what are hox genes?
genes that regulate the development of body form
what is cleavage?
when a diploid zygote undergoes a number of mitotic rapid cell divisions
what does the cleavage of the diploid zygote lead to?
a multicellular hollow blastula which is exclusive to animals
what is the internal cavity of the blastula called?
blastocoel
what does the blastula undergo, and what does it form?
blastula undergoes gastrulation forming the gastrula within different layers of gastrula tissues
how many layers of cells does the gastrula have?
2
- ectoderm
- endoderm
what are the two types of development?
- direct and indirect
what is direct development?
- embryo continues on towards animal form
what is indirect development
- there are intervening stages (ex larvae) whose morphology and behaviour differs greatly from sexually mature adult stage
what are the two traditional divisions of animals?
- without true tissues
- with true tissues - eumetazoa
what are the four body plans that animals are categorized by?
- symmetry
- layers of tissue
- body cavities
- embryonic development
what is radical symmetry?
no front/back/left/right
- can be divided into many planes of symmetry
what is bilateral symmetry?
only one plane of symmetry - two sided
- most animals
what sides does a bilateral animal have?
right and left
dorsal (top) and ventral (bottom)
anterior and posterior
what is cephalization?
development of a head
what are the 3 germ layers that give rise to tissues and organs of animal embryos?
- ectoderm
- mesoderm
- endoderm
what is the ectoderm?
outer layer that forms skin and nerves
what is the endoderm?
intervening layer forming muscle and other organs
what is the endoderm?
inner layer which lines developing digestive tube: archenteron– digestive tract, gut
what is the archenteron
archenteron– digestive tract, gut
what are diploblastic animals?
animals with 2 embryonic cell layers
- endo and ecto
ex: radiata cnidarians and comb jellies
what are triploblastic animals?
animals with 3 embryonic cell layers
- endo, meso, ecto
ex: flatworms, anthropods, vertebrates, etc
what is a true body cavity?
coelem, which is derived from the mesoderm
what is a coelomate?
animal that possesses a true ceolem
what is a pseudocoelem?
a body cavity derived from mesoderm and endoderm
what are pseudocoelomates?
animal that possesses a pseudocoelom
what are acoelomates?
animals that lack a body cavity
what are coelomates and pseudocoelomates if they are not clades?
grades: group whose members share key biological features
what are the fxns of coeloms and pseudocoeloms?
- 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
what was the first split?
- based on the presence of true tissues : Eumetazoa clade
what was the second split?
- bilateral splite : Bilatera clade
what was the third split?
- embryonic development
protosome vs deutersome
how does the protosome and deutersome differ?
- embryo cleavage
- coelom formation
- fate of blastopore
what is the cleavage of protosomes vs deutersomes?
Protosomes: spiral and determinate
Deutersomes: radial and indeterminate
what does determinate mean?
each new cell is destined to form some part of the later embryo – removal of some cells results in embryo missing organs
what does indeterminate mean?
each cell in early stages of cleavage retains capacity to develop into a complete emrbyo
what is the coelom formation of protosomes vs deutersomes?
Protosomes: splitting of solid masses of mesoderm forms coelom
Deutersomes: mesoderm buds from wall of archenteron to form coelom
fate of the blastospore protosomes vs deutersomes?
Protosomes: blastopore becomes mouth
Deutersomes: blastopore becomes anus
