animal diversity pt 2 (germ layers -> protostomes/deuterostomes)

what are the 3 germ layers?

1) ectoderm

2) endoderm

3) mesoderm

ectoderm

located on the surface and gives rise to the skin and nervous system

endoderm

the innermost layer

gives rise to the complete digestive tract

mesoderm

located between the ectoderm + endoderm

→ gives rise to everything in between (muscles + organs that are outside the digestive system)

what animals have 2 germs layers? endoderm + ectoderm? what is this called?

comb jellies, jelly fish, corrals

→ “diploblastic”

animals with 3 germ layers (ecto+endo+meso) are called what?

triploblastic

coelomate

animals with a true body cavity covered continuously by an inner + outer layer of tissue

pseudocoelomate

body cavity is only partially lined by mesoderm

acoelomate

no space between the germ layers, no body cavity

what happens to a protostome during cleavage development?

• develop by spiral cleavage

→ smaller cells lie in grooves between bigger cells

• determinate cleavage meaning that the embryonic cells are destined to become a specific tissue type

deuterostome

• develop by radial cleavage

→ cells are aligned

• indeterminate cleavage meaning that the embryonic cells can become any type of tissue

protostomes have what type of cleavage?

spiral + determinate

deuterostomes have what type of cleavage?

radial + indeterminate

do protostomes form the mouth or anus first?

mouth

do deuterostomes form the mouth or anus first?

anus