| A | B |
|---|
| abdomen | the rear segments of an arthropod |
| acoelomate | an organism that has no spaces between its three tissue layers |
| animal | multicellular, heterotrophic eukaryote with ingestive nutrition and no cell walls |
| Annelida | coelomate protostomes with segmented bodies consisting of metameres and a closed circulatory system |
| anterior | toward the head (front) of the animal |
| archenteron | primitive gut cavity formed during gastrulation |
| Arthropoda | protostome coelomates with exoskeleton and jointed limbs |
| Aschelminthes | protostome pseudocoelomates with two opening digestive tube |
| asymmetry | no recognizable regular body shape |
| bilateral symmetry | right and left sides of animal are mirror images |
| Bivalva | sedentary mollusks with two shells |
| blastocoel | fluid filled cavity of blastula |
| blastopore | opening of archenteron formed during gastrulation |
| blastula | embryonic stage - hollow ball of cells |
| book lung | stacks of gills used by spiders to get oxygen |
| centipedes | carnivorous myriopods |
| Cephalopod | subphylum of mollusks - have muscular foot split into tentacles |
| Cestoda | tapeworms |
| Chelicerates | arthropods without antennae or jaws |
| Cnidaria | radial acoelomates that have stinging cells on their tentacles |
| cnidocyte | stinging cells in jellyfish and polyps |
| coelom | body cavity in mesoderm |
| compound eye | light-sensing organ composed of several light-sensing facets |
| connective tissue | loosely connected cells and the matrix they secrete - help support body parts |
| Crustacea | arthropods with jaws, limbs composed of two branches and two pairs of antennae |
| Ctenophora | bilaterally symmetrical acoelomates that move using rows of cilia |
| deuterostomes | organisms whose anus forms from their blastopore |
| ectoderm | tissue layer that makes nervous and skin tissue |
| endoderm | tissue that gives rise to the digestive tube |
| epithelium | cell layer that lines a body surface open to air or internal spaces |
| exoskeleton | hard covering on outside of body providing protection and support |
| Eumetazoa | animals with true tissues |
| foot | muscular organ of mollusks used for locomotion |
| Gastropoda | mollusks having well developed head, single external shell and twisted body |
| gastrula | embryonic stage in which three tissue layers form |
| Hirudinea | flattened annelids that are usually parasitic |
| Insecta | uniramian arthropods with one pair of mandibles and 3 pairs of unbranched jointed legs |
| Malpighian tubules | kidney-like structure used to regulate water balance in arthropods |
| mantle | shell secreting organ of mollusks |
| mantle cavity | space for the breathing organs of mollusks |
| matrix | polysaccharide, fibers and mineral salts secreted by connective tissue cells |
| medusa | free-floating cnidarian with mouth and tentacles pointing downward |
| mesenchyme | cells that move by amoeboid motion and can become several cell types |
| mesoderm | middle tissue layer that becomes connective tissue |
| mesoglea | jelly-like middle layer of cnidarians |
| metameres | nearly identical segments of annelids |
| metamorphosis | pattern of development in which young progress from egg to larva to adult |
| millipedes | plant-eating myriopods |
| Mollusca | soft bodied coelomates with shells, mantle, and muscular foot |
| molting | shedding of old exoskeleton to accomodate new growth |
| nematocyst | barbed spear fired by cnidocyte |
| Nematoda | pseudocoelomate roundworm |
| Nemertea | acoelomatewith two-ended digestive tube and circulatory system |
| nephridia | tubular excretory organs in mollusks |
| Oligochaeta | annelids lacking parapodia, but having four pairs of bundled setae on each segment |
| ommatidia | individual eye facets of compound eye |
| operculum | protective flap in gastropods, resembles trapdoor |
| organ | group of tissues working together to perform a specific function |
| parapodia | paddlelike appendages on each segment of polychaete worms |
| Parazoa | animals with no real tissues |
| Platyhelminthes | bilaterally symmetrical acoelomate flatworms |
| Polychaeta | annelids with parapodia on each body segment |
| polyp | sedentary form of cnidarian with mouth and tentacles pointing upwards |
| posterior | toward the tail of an animal |
| proglottids | repeated segments of tapeworms that is a complete reproductive unit |
| proboscis | snout |
| protostomes | organisms whose mouth forms from its blastopore |
| pseudocoelomate | organisms with a cavity between their mesoderm and endoderm |
| radial symmetry | body plan arranged in a sphere or circle |
| radula | rasping tongue of mollusks, made from chitin |
| scolex | anterior attachment organ of tapeworms |
| sessile | permanently anchored to substrate |
| setae | stiff bristlelike projections in annelids |
| spiracles | opening to respiratory system in insects |
| tagmata | fused body segments of arthropods |
| thorax | middle set of segments of arthropods |
| tissues | more than one cell type working together to provide a particular function |
| tracheae | air passage in insects |
| Trematoda | unsegmented parasitic platyhelminthes |
| Turbellaria | free-living platyhelminthes |
| Uniramia | arthropods with unbranched appendages, one pair of antennae and one pair of mandibles |
| visceral mass | main body of a mollusk |
| zygote | diploid cell formed from fusion of two haploid gametes |
