- amoebocyte
- sponge cell with multiple functions, including nutrient delivery, egg formation, sperm delivery, and cell differentiation
- Annelida
- phylum of vermiform animals with metamerism
- archenteron
- primitive gut cavity within the gastrula that opens outward via the blastopore
- Arthropoda
- phylum of animals with jointed appendages
- biramous
- referring to two branches per appendage
- captacula
- tentacle-like projection that is present in tusks shells to catch prey
- cephalothorax
- fused head and thorax in some species
- chelicera
- modified first pair of appendages in subphylum Chelicerata
- choanocyte
- (also, collar cell) sponge cell that functions to generate a water current and to trap and ingest food particles via phagocytosis
- Chordata
- phylum of animals distinguished by their possession of a notochord, a dorsal, hollow nerve cord, an endostyle, pharyngeal slits, and a post-anal tail at some point in their development
- clitellum
- specialized band of fused segments, which aids in reproduction
- Cnidaria
- phylum of animals that are diploblastic and have radial symmetry
- cnidocyte
- specialized stinging cell found in Cnidaria
- conispiral
- shell shape coiled around a horizontal axis
- corona
- wheel-like structure on the anterior portion of the rotifer that contains cilia and moves food and water toward the mouth
- ctenidium
- specialized gill structure in mollusks
- cuticle (animal)
- the tough, external layer possessed by members of the invertebrate class Ecdysozoa that is periodically molted and replaced
- cypris
- larval stage in the early development of crustaceans
- Echinodermata
- phylum of deuterostomes with spiny skin; exclusively marine organisms
- enterocoelom
- coelom formed by fusion of coelomic pouches budded from the endodermal lining of the archenteron
- epidermis
- outer layer (from ectoderm) that lines the outside of the animal
- extracellular digestion
- food is taken into the gastrovascular cavity, enzymes are secreted into the cavity, and the cells lining the cavity absorb nutrients
- gastrodermis
- inner layer (from endoderm) that lines the digestive cavity
- gastrovascular cavity
- opening that serves as both a mouth and an anus, which is termed an incomplete digestive system
- gemmule
- structure produced by asexual reproduction in freshwater sponges where the morphology is inverted
- hemocoel
- internal body cavity seen in arthropods
- hermaphrodite
- referring to an animal where both male and female gonads are present in the same individual
- invertebrata
- (also, invertebrates) category of animals that do not possess a cranium or vertebral column
- madreporite
- pore for regulating entry and exit of water into the water vascular system
- mantle
- (also, pallium) specialized epidermis that encloses all visceral organs and secretes shells
- mastax
- jawed pharynx unique to the rotifers
- medusa
- free-floating cnidarian body plan with mouth on underside and tentacles hanging down from a bell
- mesoglea
- non-living, gel-like matrix present between ectoderm and endoderm in cnidarians
- mesohyl
- collagen-like gel containing suspended cells that perform various functions in the sponge
- metamerism
- series of body structures that are similar internally and externally, such as segments
- Mollusca
- phylum of protostomes with soft bodies and no segmentation
- nacre
- calcareous secretion produced by bivalves to line the inner side of shells as well as to coat intruding particulate matter
- nauplius
- larval stage in the early development of crustaceans
- nematocyst
- harpoon-like organelle within cnidocyte with pointed projectile and poison to stun and entangle prey
- Nematoda
- phylum of worm-like animals that are triploblastic, pseudocoelomates that can be free-living or parasitic
- Nemertea
- phylum of dorsoventrally flattened protostomes known as ribbon worms
- osculum
- large opening in the sponge’s body through which water leaves
- ostium
- pore present on the sponge’s body through which water enters
- oviger
- additional pair of appendages present on some arthropods between the chelicerae and pedipalps
- parapodium
- fleshy, flat, appendage that protrudes in pairs from each segment of polychaetes
- pedipalp
- second pair of appendages in Chelicerata
- pilidium
- larval form found in some nemertine species
- pinacocyte
- epithelial-like cell that forms the outermost layer of sponges and encloses a jelly-like substance called mesohyl
- planospiral
- shell shape coiled around a vertical axis
- planuliform
- larval form found in phylum Nemertea
- polymorphic
- possessing multiple body plans within the lifecycle of a group of organisms
- polyp
- stalk-like sessile life form of a cnidarians with mouth and tentacles facing upward, usually sessile but may be able to glide along surface
- Porifera
- phylum of animals with no true tissues, but a porous body with rudimentary endoskeleton
- radula
- tongue-like organ with chitinous ornamentation
- rhynchocoel
- cavity present above the mouth that houses the proboscis
- schizocoelom
- coelom formed by groups of cells that split from the endodermal layer
- sclerocyte
- cell that secretes silica spicules into the mesohyl
- seta/chaeta
- chitinous projection from the cuticle
- siphon
- tubular structure that serves as an inlet for water into the mantle cavity
- spicule
- structure made of silica or calcium carbonate that provides structural support for sponges
- spongocoel
- central cavity within the body of some sponges
- trochophore
- first of the two larval stages in mollusks
- uniramous
- referring to one branch per appendage
- veliger
- second of the two larval stages in mollusks
- water vascular system
- system in echinoderms where water is the circulatory fluid
- zoea
- larval stage in the early development of crustaceans