mesoderm
third cell layer formed in the developing embryo
acoelomate
body plan of an organism that can be divided along any plane, through a central axis, into roughly equal halves
radial symmetry
animal that has three cell layers, with a digestive tract but no body cavities
blastula
single layer of cells that forms a fluid-filled ball during early development
deuterostome
animal in which the mouth does not develop from the opening in the gastrula
ectoderm
layer of cells on the outer surface of the gastrula
bilateral symmetry
body plan of an organism that can be divided down its length into similar right and left halves
coelom
body cavity completely surrounded by mesoderm
sessile
describes organism that dont move from place to place
ectoderm
the embryonic layer that forms the skin and nervous tissue
endoderm
the animals digestive tract forms from the
flatworm
which animal has bilateral symmetry
more muscular control
animals with bilateral symmetry find food and mates and avoid predators more efficiently because they have
filter feeding
sponges get their food by
hematocyst
coiled threadlike tubes that are sticky or barbed or that contain toxins, Cnidarians capture prey this way
Gastrovascular cavity
digestion in cnidarians takes place in the
pharynx
during feeding, planarians extend a tubelike, muscular organ, called the
scolex
a parasitic tapeworm has a knob shaped head called a
external fertilization
in................., fertilization occurs outside the animals body after eggs and sperm are released
internal fertilization
in.................., eggs remain inside the animals body and sperm are carried to the eggs
polyp
is the tube shaped body form with a mouth surrounded by tentacles
medusa
is the sexual form of a cnidarian that has a body for like an umbrella with tentacles hanging down
proglottids
a tapeworm has reproductive organs in segments called
flagellated protists
the collar cells of sponges are similar to
corals
a group of cnidarians that provide food and shelter for many kinds of animals are the
planarian
a...................... has a muscular tube called the pharynx
sponge
which is an acoelomate animal
gizzard
annelids have a digestive organ called a
mantle
in bivalves,the ............... is a membrane that sticks to both shells and forms siphons that are used for drawing in and expelling water
closed circulatory system
an animal whose blood moves throughout its body within blood vessels has a
setae
tiny bristles protruding from each segment of a segmented worm are called
false
in shelled mollusks, the radula secretes the shell
false
bivalves obtain food by predation
true
the excretory structures in mollusks are called nephridia
false
gastropods have two shells
molting
shedding of the old exoskeleton
mandible
jaw of an arthropod
gills
aquatic arthropods exchange gases through
6
how many pairs of jointed appendages do arachnids have