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Sea urchins or urchins (/ ˈ ɜːr tʃ ɪ n z /) are typically spiny, globular animals, echinoderms in the class Echinoidea. About 950 species live on the seabed, inhabiting all oceans and depth zones from the intertidal to 5,000 metres (16,000 ft; 2,700 fathoms). [1] Their tests (hard shells) are round and spiny, typically from 3 to 10 cm (1 ...
Echinus is a genus of sea urchins.Sea urchins are echinoderms that are typically spherical or flattened with a covering of spine-like structures. Sea urchins tend to be important members of their ecosystems by grazing on other organisms and stabilizing populations.
Red sea urchins are notoriously ravenous kelp-eaters and are implicated in devastating kelp beds [4] by forming grazing fronts. The intense grazing pressure exerted by urchins is an important link in a trophic cascade often observed along the west coast of North America in which sea otter predation influences urchin abundance, which in turn ...
Sea urchins are among the main herbivores on reefs and there is usually a fine balance between the urchins and the kelp and other algae on which they graze. A diminution of the numbers of predators (otters, lobsters and fish) can result in an increase in urchin numbers, causing overgrazing of kelp forests , resulting in an alga-denuded " urchin ...
Diadema antillarum has a "shell," similar to most other sea urchins. What distinguishes the Diadema is the length of its spines. Most sea urchin spines are 1–3 cm, but the spines in this species are usually 10–12 cm in length, and can grow as long as 30 cm in very large individuals.
The water vascular system is a hydraulic system used by echinoderms, such as sea stars and sea urchins, for locomotion, food and waste transportation, and respiration. [1] The system is composed of canals connecting numerous tube feet. Echinoderms move by alternately contracting muscles that force water into the tube feet, causing them to ...
Consider the sea urchin. Specifically, the painted urchin: Lytechinus pictus, a prickly Ping-Pong ball from the eastern Pacific Ocean. The species is a smaller and shorter-spined cousin of the ...
Various bottom feeding fish feed on the young sea urchins. In Jamaica, the queen triggerfish, (Balistes vetula), is the main predator. [5] During their first year, young urchins increased their diameter by about 7 millimetres (0.28 in) a month. Growth slowed thereafter and halted completely after maturity was reached while the gonads were ripening.