Echinoderm
Echinoderm
Echinoderm (pronunciation: /ˈɛkɪnoʊˌdɜːrm/; from the Greek echinos, meaning "hedgehog", and derma, meaning "skin") is a phylum of marine animals found at every ocean depth. The phylum contains about 7000 living species, making it the second-largest grouping of deuterostomes, after the chordates (which include the vertebrates, such as birds, fishes, mammals, and reptiles).
Echinoderms are characterized by radial symmetry, several arms (five or more, often in multiples of five) radiating from a central body, and a body wall stiffened by calcium carbonate plates and spines. They are also known for their remarkable capability for regeneration. Most species reproduce sexually, and the group includes some of the few animals that can regenerate a complete body from a small fragment.
Etymology
The term "echinoderm" is derived from the Greek echinos (hedgehog) and derma (skin), a reference to the spiny skin that is a common characteristic of animals in this phylum.
Classification
Echinoderms are exclusively marine and include the well-known starfish, sea urchins, sand dollars, and sea cucumbers, as well as the less familiar crinoids and brittle stars. They are classified under the Phylum Echinodermata, which is split into five extant classes:
- Asteroidea (starfish or sea stars)
- Ophiuroidea (brittle stars)
- Echinoidea (sea urchins and sand dollars)
- Crinoidea (sea lilies and feather stars)
- Holothuroidea (sea cucumbers)
Related Terms
See Also
External links
- Medical encyclopedia article on Echinoderm
- Wikipedia's article - Echinoderm
This WikiMD dictionary article is a stub. You can help make it a full article.
Languages: - East Asian
中文,
日本,
한국어,
South Asian
हिन्दी,
Urdu,
বাংলা,
తెలుగు,
தமிழ்,
ಕನ್ನಡ,
Southeast Asian
Indonesian,
Vietnamese,
Thai,
မြန်မာဘာသာ,
European
español,
Deutsch,
français,
русский,
português do Brasil,
Italian,
polski