十分急！我想知道關於starfish（動物，並不是地方名）嘅知識？唔該哂各位覯仔覯女！！！

Starfish

Statistics
Normally 10-30cm. Maximum diameter 50cm.


Habitat
Starfish can be found in rock pools and on beaches. The habitat varies and includes coarse and shelly gravel and rock. Abundance increases markedly on algal carpets as compared with fine sand. The common starfish is unusual in that it tolerates estuarine habitats. Its habitat range extends offshore for 400m.

Diet
Common starfish feed on mussels, crustaceans, worms and echinoderms (starfish or sea urchins).

Behaviour
Starfish are propelled very slowly along the sea floor by their tiny tube feet. Tube feet can produce strong suction, fixing the starfish in place and making it difficult for a predator to eat the entire organism. Occasionally starfish can be seen with missing limbs. This is not a great loss for a starfish as they can grow them back. Sometimes common starfish with six or more limbs are seen, this may be a result of the starfish accidentally growing two limbs to replace a single loss.

Starfish are active carnivores, and scavenge too. They prey on bivalve molluscs by forcing their shells open with their tube-feet. The stomach everts over or into the prey liquefying it so that it can be easily digested. In shallow waters dense congregations of starfish can be found over an expanse of several kilometres.

Marine scientists have undertaken the difficult task of replacing the beloved starfish’s common name with sea star because, well, the starfish is not a fish. It’s an echinoderm, closely related to sea urchins and sand dollars.

There are some 2,000 species of sea star living in all the world’s oceans, from tropical habitats to the cold seafloor. The five-arm varieties are the most common, hence their name, but species with 10, 20, and even 40 arms exist.

They have bony, calcified skin, which protects them from most predators, and many wear striking colors that camouflage them or scare off potential attackers. Purely marine animals, there are no freshwater sea stars, and only a few live in brackish water.

Beyond their distinctive shape, sea stars are famous for their ability to regenerate limbs, and in some cases, entire bodies. They accomplish this by housing most or all of their vital organs in their arms. Some require the central body to be intact to regenerate, but a few species can grow an entirely new sea star just from a portion of a severed limb.

Most sea stars also have the remarkable ability to consume prey outside their bodies. Using tiny, suction-cupped tube feet, they pry open clams or oysters, and their sack-like cardiac stomach emerges from their mouth and oozes inside the shell. The stomach then envelops the prey to digest it, and finally withdraws back into the body.