## a-d

### a

- abalone n. Phylum Mollusca, Class Gastropoda, Order Archaeogastropoda. Any of the edible, rock-clinging shelled molluscs (genus Haliotis) that have a flattened shell lined with mother-of pearl, with a row of openings along the outer edge.
- abarenicola n. Phylum Annelida, Class Polychaeta, Order Capitellida. A tube-dwelling, segmented worm that lives in tidal flats.
- amphioxus n. Phylum Chordata, Subphylum Cephalochordata. Any of the genusBranchiostoma, a little, fish-like, simple chordate, that lives partially buried in marine sand flats and is also known as a lancelet.
- anatomy n. A branch of study that deals with the internal structure of organisms, or simply the structural makeup of an organism or any of its parts.
- anemone n. Phylum Cnidaria, Class Anthozoa, Order Actiniaria. A typically solitary, soft-bodied, marine polyp with sixfold symmetry and clusters of tentacles superficially resembling a flower.
- anesthetic n. A substance that can produce a loss of sensation with or without loss of consciousness.
- animal n. An organism with multiple differentiated cells (multicellular) that contain nuclei (eukaryotic), lack rigid cell walls, are bound together by collagen, gain their energy from other organisms, and typically reproduce by sexual reproduction.
- animal body plan n. The unique assemblage of structural features that characterizes animals of a distinct phylum.
- annelid n. Phylum Annelida. A group of invertebrates, including segmented worms with a true body cavity. (Annelida literally means little rings.)
- anomalocaris n. An extinct animal known from fossils from the Cambrian Explosion period over 500 million years ago that some scientists suggest is related to the Arthropoda phylum.
- antennae n. Paired sensory appendages found in most arthropods.
- antibiotics n. A substance produced by or derived from a microorganism and able to inhibit or kill another microorganism.
- appendage n. An outgrowth that extends from an animal’s body. If present on a body segment, appendages are usually paired.
- aristotle n. A 4th century Greek philosopher (384-322 B.C.) who was a student of Plato's (427 B.C.-347 B.C.) and compiled the first large-scale description and categorization of animal life, entitled Historia Animalium.
- arthropod n. Phylum Arthropoda. A group of animals possessing regional segmentation, jointed appendages, and an exoskeleton. (Arthropod literally translates to "jointed foot.")
- asteroid n. A rocky body, less than 1000 kilometers across, in orbit around the sun.
- aysheaia n. An extinct, marine, worm-like animal from the Cambrian Explosion period akin to modern-day velvet worms ( Onychophorans).

### b

- backbone n. The bony, internal axis of a vertebrate body that grows with the animal while providing attachment for muscles and support for the body.
- bacteria n. A microorganism without a nucleus (prokaryote).
- basal adj. Having to do with the base, bottom, or foundation of something; essential, vital, primary.
- bell n. See medusa
- bilateral adj. Any body form with a central longitudinal plane that divides the body into two equal but opposite halves.
- bone n. The main material of most vertebrate skeletons, consisting of approximately equal volumes of collagen fibers (the fibers from which tendons are made) and crystals of bone salt (containing calcium phosphate and hydroxide).
- bone remodeling n. The process of restructuring living bone in response to external and internal stresses.
- book gills n. Organs of gas exchange, consisting of stacked plates that are flapped during respiration.
- brain n. A grouping of nerve structures, typically at the front (anterior) end of the body, that help create and integrate commands sent to the rest of the body.
- brittlestar n. Phylum Echinodermata, Class Ophiuroidea. A type of echinoderm with a central disc and long, flexible arms used in rapid locomotion.
- buoyancy n. The force exerted by water that counteracts an animal’s weight.
- burgess shale n. A fossil site in the Rocky Mountains of British Columbia, Canada, where a wealth of fossils from the Cambrian Explosion period has been discovered.

### c

- calliostoma n. Phylum Mollusc, Class Gastropods, Subclass Prosobranchia. A type of marine shelled mollusc that lives off the California coast.
- cambrian explosion n. A burst of evolutionary origins when most of the major body plans of animals appeared in a relatively brief time in geological history; recorded in the fossil record approximately 525 to 545 million years ago.
- cambrian period n. A period of geologic time when the vast majority of animal body plans appeared that extends from approximately 545 to 490 million years ago.
- canadia n. Phylum Annelida, Class Polychaeta. An extinct animal known from Cambrian Explosion fossils that resembles a modern marine polychaete or annelid worm.
- carnivores n. Phylum Chordata. Any mainly, or exclusively meat-eating organism; alternatively, any member of the order Carnivora in the phylum Chordata.
- carolus linnaeus n. A Swedish physician (1707-1778) who founded taxonomy, the branch of biology concerned with naming and classifying the diverse forms of life, and devised the two-part (binomial) naming system that names animals according to genus and species.
- cell types n. Structurally and functionally different cells that have become specialized in a multicellular organism.
- centipede n. A terrestrial arthropod with numerous segments and one pair of legs per segment. They are carnivores and possess venom. They are members of the subphylum Myriapoda and the class Chilopoda.
- chambered nautilus n. Phylum Mollusca, Class Cephalopoda, Subclass Nautiliodea. Any genus of Nautilus of the South Pacific and Indian Oceans with a spiral chambered shell that is pearly on the inside.
- charles darwin n. The father of modern biology (1809- 1882), who in his book, The Origin of Species, put forth the theory of descent with modification commonly referred to as evolution by means of natural selection.
- chemoreception n. The process of receiving stimuli from particular molecules, which results in the sense of smell and taste.
- choanocyte n. Collared cells with tail-like flagella that produce a current that draws water past their collars where food gets captured.
- chordate n. Phylum Chordata. A diverse phylum (grouping) of animals that possesses at some stage of life a notochord, a dorsal, hollow nerve cord, pharnygeal gill slits, and typically a tail that extends past the anus.
- chromatophore n. Pigment-containing skin cells, the control of which determines the rapid change of color patterns in an organism.
- cilia n. (Singular: cilium) A hair-like growth from a cell that when present in large numbers on surfaces can produce currents to move water and/or propel an animal across a carpet of mucus, e.g., flatworms.
- cnidarian n. Phylum Cnidaria. A group of animals that includes corals, hydras, jellyfish, Portuguese man-of-war, sea anemones, sea pens, sea whips, and sea fans; and has the defining feature of stinging structures called nematocysts. (See nematocyst.)
- cnidocyte n. The cell in cnidarians that fires the nematocyst.
- cockle n. Phylum Mollusca, Class Bivalvia. Any of the approximately 250 species of marine bivalve molluscs, or clams, of the family Cardiidae, that are distributed worldwide and range from about one centimetre (0.4 inch) in diameter to about 15 cm (about 6 inches).
- coelom n. a fluid-filled body cavity in many phyla which surrounds the internal organs.
- collagen n. A type of protein in animal cells that forms strong fibers, found extensively in connective tissue, intracellular matrix, and bone; one of the most abundant proteins in the animal kingdom.
- colobonema n. Phylum Cnidaria, Class Scyphozoa. A specific group of deep-sea jelly which has the ability to drop its tentacles as a decoy.
- comb jelly n. Phylum Ctenophora. An exclusively marine phylum that derives its name (ctene, or "comb," and phora, or "bearer") from the eight rows of hair-like combs that move the animal by beating.
- commensalism n. An association between two organisms in which one benefits and the other derives neither benefit nor harm: the scale worm commensally lives on the sea star.
- coral polyps n. Phylum Cnidaria, Class Anthozoa, Order Scleractinia. A form of coral that is fixed to the seafloor and manufactures the calcium-carbonate matrix (material) of the reef.
- coral reef n. Structures composed of the living and dead colonies of cnidarians most commonly found in the tropics.
- crinoid n. Phylum Echinodermata, Class Crinoidea. A group of echinoderms known commonly as the feather stars and sea lilies.
- cryptic adj. Serving to help camouflage potential prey.

### d

- darwin's theory of evolution n. The environmental determination of differential survival -- popularly known as survival of the fittest, or natural selection.
- dermasterias n. Phylum Echinodermata, Class Asteroidea. A type of sea star commonly known as the leather star.
- detritovores n. Organisms that eat small particles of dead organic matter (detritus).
- detritus n. Dead organic matter.
- devonian n. An interval of the Paleozoic Era that follows the Silurian and precedes the Carboniferous. It is thought to have covered the span of time between about 408 and 360 million years ago. It is commonly known as the Age of Fishes.
- dinosaurs n. Phylum Chordata, Class Reptilia The common name given to any of certain extinct archosaur reptiles, often very large, that thrived worldwide for some 150 million years and died out at the end of the Mesozoic Era, about 65 million years ago.
- diopatra n. Phylum Annelida, Class Polychaeta, Order Eunicida. A marine tube-dwelling, segmented worm that frequents mud flats.
- dna n. DeoxyriboNucleic Acid -- the carrier of genetic information in all cells and made of four small molecules called nucleotides.
- drag n. The primary force that resists forward movement, and is dependent upon the animal's shape and how that shape interacts with the water.