Sea stars are not fish: That’s why marine scientists don’t
call them starfish. A sea star is an echinoderm, a close relative of sea
urchins and sand dollars.
There are many kinds: Some 2,000 species of sea star live everywhere from tropical habitats to the cold ocean floor. Five-arm varieties are most common, but species with 10, 20, even 40 arms exist.
They have no brain and no blood: They use sea water to pump nutrients throughout their bodies.
They can regrow arms and sometimes their entire bodies: That’s because most or all of their vital organs are in their arms. A few species can grow an entirely new sea star from just part of a severed arm.
They can eat prey outside their bodies: Using their tiny, suction-cupped tube feet, they pry open clams or oysters. The stomach emerges from the sea star’s mouth, oozes inside the shell and envelops the food to digest it. Then the stomach withdraws back into the sea star’s body.
They can live a long time: Their average life span in the wild is 35 years.
They can weigh up to 11 pounds and vary in size from 4.7 to 9.4 inches.
Image above courtesy of Federico Stevanin/FreeDigitalPhotos.net; photos below courtesy of MorgueFile.
Source: National Geographic online
There are many kinds: Some 2,000 species of sea star live everywhere from tropical habitats to the cold ocean floor. Five-arm varieties are most common, but species with 10, 20, even 40 arms exist.
They have no brain and no blood: They use sea water to pump nutrients throughout their bodies.
They can regrow arms and sometimes their entire bodies: That’s because most or all of their vital organs are in their arms. A few species can grow an entirely new sea star from just part of a severed arm.
They can eat prey outside their bodies: Using their tiny, suction-cupped tube feet, they pry open clams or oysters. The stomach emerges from the sea star’s mouth, oozes inside the shell and envelops the food to digest it. Then the stomach withdraws back into the sea star’s body.
They can live a long time: Their average life span in the wild is 35 years.
They can weigh up to 11 pounds and vary in size from 4.7 to 9.4 inches.
Image above courtesy of Federico Stevanin/FreeDigitalPhotos.net; photos below courtesy of MorgueFile.
Source: National Geographic online
