invertebrate parts

ostia

pores on sea sponge which water enters through

osculum

large opening through which water exits after circulating through body

spicule

spike-like structure in sponges that provides support and protection

spongin

flexible protein fiber in sponges that forms part of skeleton

choanocyte

collar cells; specialized sponge cells that create water currents and capture food particles

pinacocyte

flat cells that form outer layer of sponge, providing protection and structure

amoebocyte

mobile sponge cell that transports nutrients, removes waste, and produces skeletal fibers

polyp

sessile body of cnidarian; cylindrical with mouth and tentacles facing upward

medusa

free-swimming, bell-shaped body form of cnidarian, mouth and tentacles facing downward

epidermis

outermost layer of cells covering an organism, providing protection

tentacles

flexible, elongated appendages around mouth used for capturing food and defense

cnidocyte

specialized stinging cells in cnidarians used for capturing prey and defense

oral surface

side of cnidarian where mouth is located

gastrovascular cavity

central digestive chamber in cnidarians where food is broken down and nutrients are distributed

extracellular digestion

process of breaking down food outside cells, typically in digestive cavity, before nutrients are absorbed

intracellular digestion

process of breaking down food within cells, usually inside specialized food vacuoles

aboral surface

side of cnidarian opposite the mouth

proboscis

elongated, tubular feeding or sensory organ found in certain animals, used for capturing or ingesting food

chaetae

bristle-like extensions on segmented worms that aid in movement and anchoring

radula

toothed, ribbon-like structure in gastropods used for scraping or cutting food

byssal threads

strong, fibrous filaments that bivalves use to attach themselves to surfaces

chromatophores

pigment-containing cells in animals that allow them to change color for camouflage, communication, or signaling

flagellum

long, whip-like appendage that enables cells or organisms to move through water