A phylum of the most familiar marine invertebrates. Its class Stelleroidea contains two subclasses, the Asteroidea (the STARFISH or sea stars) and the Ophiuroidea (the brittle stars, also called basket stars and serpent stars). There are 1500 described species of STARFISH found throughout the world. The second class, Echinoidea, contains about 950 species of SEA URCHINS, heart urchins, and sand dollars. A third class, Holothuroidea, comprises about 900 echinoderms known as SEA CUCUMBERS. Echinoderms are used extensively in biological research. (From Barnes, Invertebrate Zoology, 5th ed, pp773-826)

Small solar system planetary bodies including asteroids. Most asteroids are found within the gap lying between the orbits of Mars and Jupiter.

A class of Echinodermata characterized by long, slender bodies.

Somewhat flattened, globular echinoderms, having thin, brittle shells of calcareous plates. They are useful models for studying FERTILIZATION and EMBRYO DEVELOPMENT.

The relationships of groups of organisms as reflected by their genetic makeup.

Animals that have no spinal column.

An element with the atomic symbol N, atomic number 7, and atomic weight [14.00643; 14.00728]. Nitrogen exists as a diatomic gas and makes up about 78% of the earth's atmosphere by volume. It is a constituent of proteins and nucleic acids and found in all living cells.

Lists of words, usually in alphabetical order, giving information about form, pronunciation, etymology, grammar, and meaning.

Common name for large, quilled rodents (RODENTIA) comprised of two families: Old World porcupines (Hystricidae) and New World porcupines (Erethizontidae).

A genus of large SEA CUCUMBERS in the family Holothuriidae possessing thick body walls, a warty body surface, and microscopic ossicles.

A genus of very large, epibenthic SEA CUCUMBERS in the family Stichopodidae, commercially harvested in Southeast Asia for food.

The study of the physical, chemical, hydrological, and biological aspects of fresh water bodies. (EPA Terms of Environment: Glossary, Abbreviations and Acronyms [Internet] US Environmental Protection Agency [cited 2008 Sep 25] available from http://www.epa.gov/OCEPAterms/aterms.html)

The science that deals with the ocean and its phenomena. (Webster, 3d ed)

A genus of gram-negative, chemoorganotrophic bacteria in the family CYTOPHAGACEAE. In some species there is a cyclic change in cell morphology.

A plant genus of the family Plantaginaceae. Members contain bis-sesquiterpene and iridoid glucosides.

An element with atomic symbol O, atomic number 8, and atomic weight [15.99903; 15.99977]. It is the most abundant element on earth and essential for respiration.

The movement of the BLOOD as it is pumped through the CARDIOVASCULAR SYSTEM.

The HEART and the BLOOD VESSELS by which BLOOD is pumped and circulated through the body.

The exchange of OXYGEN and CARBON DIOXIDE between alveolar air and pulmonary capillary blood that occurs across the BLOOD-AIR BARRIER.

The application of scientific knowledge or technology to the field of radiology. The applications center mostly around x-ray or radioisotopes for diagnostic and therapeutic purposes but the technological applications of any radiation or radiologic procedure is within the scope of radiologic technology.

A branch of biology dealing with the structure of organisms.

Processes and properties of the CARDIOVASCULAR SYSTEM as a whole or of any of its parts.

Factors which produce cessation of all vital bodily functions. They can be analyzed from an epidemiologic viewpoint.