1/28/20 Flashcards
earliest animals are most easily defined by ____ and ____
body plan symmetry; embryo development
three types of animal symmetry
asymmetry, radial symmetry, and bilateral symmetry
this type of symmetry has no dividing planes/axis
asymmetry
this type of symmetry has no anterior/posterior ends and is divided along multiple planes
radial symmetry
this type of symmetry is divided along a single plane
bilateral symmetry
animals with radial symmetry have an ____ end and an ____ end
oral; aboral
the area of a radially symmetric animal where the mouth can be found
oral
the area of a radially symmetric animal opposite of the mouth
aboral
bilaterally symmetric animals have a ____ and ____, ____ and ____, ____ and ____, and _____ and ____
front;back, top;bottom, anterior;posterior, dorsal;ventral
the head end of a bilaterally symmetric animal
anterior
the tail end of a bilaterally symmetric animal
posterior
the backside of a bilaterally symmetric animal
dorsal
the front side of a bilaterally symmetric animal
ventral
the earliest animals had a(n) ____ symmetry
asymmetric
____ symmetry was the second to evolve
radial
nearly all extant animals have ____ symmetry
bilateral
an egg that has been fertilized by a sperm
zygote
cell division without growth
cleavage
Phyla ____ and ____ lack a distinct cleavage pattern
Porifera; Cnidaria
most bilateral animals divide in ____ or ____ cleavage
radial; spiral
cleavage planes are symmetrical to polar axis and produce tiers of cells on top of each other forming identical blastomeres that could each form a complete embryo
radial cleavage
cells cleave at an angle to polar axis and cleave asymmetrically, producing small cells on top of large (nonidentical blastomeres could not individually form a complete embryo)
spiral cleavage
cells formed during cleavage
blastomeres
all ____ have spiral cleavage
Lophotrochoza
all ____ have radial cleavage
Deuterostomia
fluid-filled ball of cells that forms from the zygote
blastula
name for the cavity in the center of the blastula
blastocoel
Phylum(s) ____ progress into the blastula stage
ALL
Phylum ____ does not progress past the blastula stage
Porifera
blastula forms into ____
gastrula
process by which one end of the gastrula invaginates
gastrulation
pocket formed in gastrula following gastrulation
gastrocoel
germ layers of the gastrula
ectoderm and endoderm
animals with two germ layers
diploblasts
the third layer that forms in the gastrula of some species
mesoderm
animals with three germ layers
triploblasts
the mesoderm forms into this following development
coelom
the area in the body that stores all organs
coelom
when the mesoderm lines only the outer edge of the blastocoel
pseudocoelom
when the mesoderm forms into a spongy tissue that fills the blastocoel
acoelomate body
when the mesoderm lines both the outer and inner edges of the blastocoel
coelomate
forms everything from the mouth to the anus
endoderm
forms muscle, bone, connective tissue, circulatory system, adipose tissue, etc.
mesoderm
forms skin, teeth, hair, CNS, eyes, etc.
ectoderm
all ____ and ____ are triploblasts
Protostomes; Deuterostomes
all ____ and ____ are diploblasts
Cnidarians; Ctenophores
mesoderm type is/isn’t a reliable character
isn’t
> 95% of animals have this type of mesoderm
coelomate
in ____, the blastophore develops into the mouth first
Protostomes
in ____, the blastophore develops into the anus first
Deuterostomes
ways to define an animal
multicellular eukaryotes, heterotrophic, no cell walls, motile (at some life stage), and development into at least blastula
hierarchy of complex bodies
protoplasm>cellular>tissue>tissue-organ>organ-system
thought to be earliest ancestor of all animals
Choanoflagellates
earliest animals
Phylum Porifera
characters of Porifera
sessile as adults, “skeleton” made of spicules/collagen, no digestive system, no respiratory system, no excretory system, no nervous system, all aquatic (mostly marine), no tissue, mostly hermaphroditic, can produce asexually
