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Glossary


Aboral - opposite the mouth.

Adapical - or adoral, opposite the apex or top.

Ambulacral area - one of the five zones of narrower plates in the echinoid skeleton.

Biserial - in a double row. see uniserial

Blastopore - a deep depression on the side of a blastula-stage embryo that eventually becomes the mouth, in protostomes, or the anus in deuterostomes

Caecum (plural - Caeca) - a bind sac or side projection of the mantle or gut.

Cladogram - a two way branching diagram indicating the closeness of relationship of a number of taxa

Class - a division in classification, containing one or more orders and is contained within a phylum.

Coelum - the body cavity in animals found between the gut and the outer body surface.

Deuterostome - animal in which the embryonic blastopore often develops into the anus

Disarticulation - the breaking apart and losing natural connections, typically occurring after death and referring to the skeleton.

Dorsal - upper surface or side.

Gonad - the organ that produces sex cells; the ovary or testes.

Madreporite - Small button-like structure often resembling a small wart on the central disk. This plate in the echinoid skeleton positioned near the anus is used to filter water into the sea star's water-vascular system.

Mesoderm - the tissue type that forms a variety of organs between the ectoderm and the endoderm of many animals.

Monophyletic group - a group that includes all the descendants of a common ancestor.

Nerve plexus - a network of interlacing nerves

Order - a classification division that contains one or more families and is contained within a class.

Ossicle - one segment of the arm of an ophiuroid, a vertebrae.

Pentameral - Echinoderms (e.g. sea urchins and starfish) possess a variant of radial symmetry in which orientations of 72° rotation are considered equivalent (5-fold rotational symmetry)

Phylum - a division in classification that contains one or more classes, and is contained in a kingdom. Phylogenetic describes the evolutionary relationship.

Stenohaline - an organism that can only tolerate a narrow range of salinity.

Suspension feeder - an animals that feeds on small food particles suspended in the water.

Test - the skeleton.

Tube feet - these are the many small tubular projections found on the ventral face of a sea star's arms. These small fleshy musculatures project through the skeleton of an echinoderm and function in cleaning, feeding, and locomotion. Also sometimes referred to podia.

Uniserial - in a single row.

Water vascular system -The water vascular system is a hydraulic system used by Echinoderms, for locomotion, food and waste transportation, and respiration. (Solomon, 2002). Composed of water filled tube feet and ampulla, Echinoderms move by contracting the muscles around the ampulla forcing water in the tube feet, which causes the foot to extend propelling the animal forward (Solomon, 2002).

Glossary after Benton and Harper 1997 and Clarkson 2001

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Author: Elizabeth Sweet
Last updated: 22nd November 2005
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Websites produced by students on the MSc Palaeobiology programme in the Department of Earth Sciences at the University of Bristol for academic year 2005-6