Chapter 32 Flashcards
animals
heterotrophs
cells lack cell walls
animals
conduct nerve impulses
nervous tissue
allow body movement
muscle tissue
bodies are held together by
structural proteins eg. collagen
most animals reproduce sexually/___ stage dominates life cycle
diploid
In most animals, a small sperm fertilizes a large egg to form a
zygote
cells arrange themselves in a hollow ball called a
blastula
during this phase, the cells become organized into layers of embryonic tissues from which the adult body parts are produced
gastrulation (gastrula)
Most animal life cycles include an immature form called a
larva
this undergoes metamorphosis to give the adult form
larva eg. a tadpole and the adult frog
___ ___ of a common ancestor of living animals lived in the ___ of the Earth about ___ ___ years ago.
Fossil evidence; waters; 700 million
Animals started to move to land ___ ___ years ago.
460 million
Fossil evidence that vertebrates made transition to land from water around ___ ___ years ago.
360 million
Animals classified according to ___ of their bodies, or lack of it
symmetry
Least evolved animals= ?
no symmetry eg. sponge
top side and bottom side but no front and back ends, no left and right sides
radial symmetry eg. sea anemone
2 sided symmetry
bilateral symmetry
top side
dorsal
bottom side
ventral
head end
anterior
tail end
posterior
development of a head
cephalization