Terms and Definitions

aboral - on a two-sided invertebrate, the surface opposite the mouth

algae — (s. alga) - simple aquatic plants. Unlike other plants, algae have no roots, leaves, or stems.

calcareous - containing calcium carbonate (a compound of calcium)

chelipeds - a clawed thoracic appendage found in decapod crustaceans

chitin (KI-t'n) - a hard substance in the external skeleton of arthropods

class - a division of animal or plant classification. A class is a subdivision of a phylum.

crustacean - an arthropod of the class Crustacea, including mostly aquatic forms such as lobsters, crabs, shrimps, and barnacles

detritus (de-TRI-tus) - tiny pieces of dead and decomposing plants and animals

dorsal - pertaining to the back or top surface of the body

ecosystem - a unit of plants, animals, and non-living components of an environment that interact

environment - one's surroundings

evagination - the acts of pushing out, as when sea stars evert their stomachs during feeding

intertidal zone - the shoreline area within the tidal range

invertebrate - any animal that lacks a spinal column

gamete - a male or female reproductive cell

kelp - large brown marine algae, including giant kelp

marine - related to the seas or oceans

oral - of or pertaining to the mouth

order - a division of animal or plant classification. An order is a subdivision of a class

papulae - the tiny external respiratory organs of sea stars

parasite - an organism that lives in or on, and feeds on, a host organism, harming the host

pedicellariae - tiny, pincherlike projections found on the dorsal surfaces of some sea stars

phylum — (pl. Phyla) - a division of animal or plant classification. A phylum is a subdivision of a kingdom.

piling - a column made of wood, steel, or concrete that holds up a dock, wharf, or pier

plankton - free-floating, microscopic plants and animals

predator - an animal that eats another animal

prey - an animal eaten by another animal

radula - a ribbonlike structure bearing rows of teeth found in the "mouths" of many molluscs. The molluscs use their radula for rasping and scraping.

substrate - the surface upon which an organism lives

sessile - attached to the bottom or another hard substrate

territorial - establishing and defending a particular territory

telson - the last segment of the thorax of an arthropod or an extension of the last segment such as a scorpion's stinger or a lobster's tail fan

tidal range - the difference between the highest and lowest tides

tide - the rise and fall of the sea level along the coasts, caused by the gravitational pull of the sun and moon

uropods - in some crustaceans, a flattened pair of appendages at the posterior end of the abdominal section

ventral - pertaining to the underside or bottom surface