introduction to animals crossword
open
circulatory system in which blood empties into the body cavity to bathe tissues
yolk
part of an egg containing the food supply
pharyngeal pouches
outpockets of the anterior digestive tract that may develop into respiratory structures
lungs
respiratory structure that removes oxygen from the air
gills
respiratory structures that remove oxygen from water
closed
respiratory system in complex invertebrates and all vertebrates
anterior
end where the head is located
diploid
fertilization restores this chromosome numer
zygote
fertilized egg cell
notochord
flexible, dorsal rod of tissue in chordates that may become the backbone
coelom
fluid filled body cavity
three
number of tissue layers in more complex invertebrates and all vertebrates
endoskeleton
skeletal system in all vertebrates
specialization
adaptation of cells for different functions
multicellular
all animals are this because they are made of many cells
vertebrates
animals with a backbone
dorsal
back side
cephalization
concentration of sensory organs on the head end of an organism
indirect
development in which the animal goes through a larval stage
direct
development in which the young animal looks like that adult, only smaller
gut
digestive tract
kidneys
excretory structures in vertebrates to get rid of nitrogenous wastes
ventral
front side
endoderm
germ layer that forms the digestive tract
blastula
hollow ball cell stage of a developing zygote
ingestion
how animals take in food
integument
outer coverings of an animal
ectoderm
outer germ layer
mesoderm
middle germ layer that forms muscles
invertabrates
more than 95% of all animals are this
two
number of tissue layers in Cnidarians
hermaphrodite
organism that produces both sperm and egg
protostome
organisms whose first opening becomes the mouth
archenteron
primitive gut
segmentation
refers to a body composed of repeating units
exoskeleton
rigid outer covering in all arthropods
cleavage
series of rapid cell division following fertilization
neurons
specialized nerve cells
asymmetry
sponges have this symmetry
radial
symmetry where body parts are in circle arranged around a central axis
bilateral
symmetry where organisms have a right and left side
posterior
tail end of the organisms
germ layers
tissue layers
oxygen carbon dioxide
two gases exchanged in animals
fertilization
union of egg and sperm cells
ammonia
waste excreted by simple aquatic invertebrates
fluid
what fills the body cavity of many animals and aids in movement and support
