Starfish, also known as sea stars, are marine creatures with star-shaped body structure. Starfish are actually not a fish as mistaken by their name. They do not have spine and fins like fish.
They are hard-skinned animals with no brains and blood. Their nervous system is spread through their arms and their ‘blood’ is actually filtered sea water. They do not have legs and have only arms called rays. They typically have five or more arms that comes in different colours. If they loose an arm, it will always regrow. They have feet but no toes. They glide and slide on tiny tube feet and move as slow as a snail. They have no eyes, nose or ears. Starfish only have eyespots at the tip of each arm that are only able to make differences of light and dark. They have the ability to squeeze their bodies into small spaces that helps to protect themselves from their predators. There are about 2,000 different species of starfish worldwide.
Starfish are carnivores and their favourite food is oyster. They would eat anything that is small enough for its mouth and slow enough to be caught. They feed on coral, small fish and other ocean animals. They use their tube feet to hang on to the shell of mussels, clams or oysters while pulling the two halves of the shell apart. As soon as a gap opens, they extend their stomach into the shell to digest the food.
Starfish live in every ocean of the world. They are mostly found on the rocky sea floor.
Their habitats could range from tropical coral reefs to deep-sea floor. Starfish are found in most of temperate and tropical oceans of the world. They also live under the sand on beaches.
Starfish lay numbers of eggs into the ocean if the fertilisation is external. After eggs are hatched, starfish babies (larvae) float in the sea. Newly hatched starfish larvae that look like tiny, transparent, bilaterally-symmetrical, swim in the sea till they develop into adult starfish. They float for about two months and then the larvae sink to the bottom of the ocean. There they will change the shape and slowly grow into the adult starfish.
Starfish often reproduce with the detached part of their arms. Once detached, the arm will eventually grow into another independent starfish. This process is called fragmentation. A starfish arm can only produce a new individual starfish if the arm is split off along with some of the central part of their body.
Generally, the life span of the common starfish is between five years to 10 years. — Compiled
by Merina Pradhan