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Saturday 28 April 2018

Starfish

Starfish are star-shaped echinoderms with arms radiating from a central body. Typically they have five arms, but some species have more.


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There are about 1,500 living species of starfish to be found on the seabed in all the world's oceans.

The sunflower seastar is the largest starfish and has an arm-span of 1 meter (3.3 ft). It has 16 to 24 arms with powerful suckers

Starfish may shed their own arms in order to keep cool in extreme temperatures.

Some starfish can regenerate their entire body from a single arm from just 1cm (0.4in) long. In some species of starfish, a large female can split in half, each half becoming male which changes back into female once they grow big enough.

Starfish can see with compound eyes at the ends of their arms.

The upper surface of the starfish may be smooth, granular or spiny, and is clad in overlapping plates. Many species are brightly colored in shades of red or orange, while others are blue, grey or brown.

Astropecten aranciacus starfish. By Rpillon

Starfish have tube feet operated by a hydraulic system and a mouth at the center of the lower surface.

Starfish open up clams or oysters by using their tiny, suction-cupped tube feet.

Most starfish are voracious predators, either swallowing their prey whole or turning their stomachs inside out to engulf it.

A starfish does not have the capacity to plan its actions. If one arm detects an attractive odor, it becomes dominant and temporarily over-rides the other arms to initiate movement towards the prey.

A Pisaster ochraceus starfish consuming a mussel in central California. Wikipedia

The starfish is one of the only animals who can turn it's stomach inside-out.

Starfish do not have blood. Instead they use seawater in their vascular system to circulate nutrients.

Starfish have complex life cycles and can reproduce both sexually and asexually.

Two million eggs a year are produced by the female starfish, but 99 per cent of them get eaten by other marine animals.

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