Echinodermata
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)
Minor Planets
Sea Urchins
Nitrogen
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.
Dictionaries as Topic
Porcupines
Common name for large, quilled rodents (RODENTIA) comprised of two families: Old World porcupines (Hystricidae) and New World porcupines (Erethizontidae).
Holothuria
A genus of large SEA CUCUMBERS in the family Holothuriidae possessing thick body walls, a warty body surface, and microscopic ossicles.
Stichopus
A genus of very large, epibenthic SEA CUCUMBERS in the family Stichopodidae, commercially harvested in Southeast Asia for food.
Limnology
Flexibacter
Veronica
Oxygen
Blood Circulation
The movement of the BLOOD as it is pumped through the CARDIOVASCULAR SYSTEM.
Cardiovascular System
Pulmonary Gas Exchange
The exchange of OXYGEN and CARBON DIOXIDE between alveolar air and pulmonary capillary blood that occurs across the BLOOD-AIR BARRIER.
Technology, Radiologic
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.
Cardiovascular Physiological Phenomena
Processes and properties of the CARDIOVASCULAR SYSTEM as a whole or of any of its parts.