Md Arif Hossain
Starfishes are among the best known echinoderms. Most starfish have a central disk with five arms, or rays spreading out like spoke on a wheel. Some types, however, have as many as twenty arms. The undersides of these arms are covered with hollow tubes called “tube feet”. These tubes are connected to an internal network of canals that runs through the starfish. The movement of water through this network allows the tube feet to act like tiny suction cups. The tube feet are used for movement and food getting. The starfish can wrap its arms around a clam, using its suction feet to hold on. The tube feet pull the clam open.
Then, a strange thing happens. The starfish’s stomach stretches out of its body through its mouth and enters the clam. It actually digests the soft body of the clam while it is inside the clamshell. The digested material is then sucked into the starfish.
A star fish can eat up to a dozen clams a day. For this reason, the crews on fishing boats try to kill any starfish they find. They used to chop up the starfish and throw the pieces back into the ocean. Unfortunately, any pieces that had part of the central disk grew into new starfish. This is now it was discovered that starfish can regenerate itself. So, to be killed, starfish have to be dried.
The writer is studying in Electrical Technology department in Mymensingh polytechnic institute