Must Know Starfish Facts
Here are a few starfish facts for those among us who have spent time enjoying the beauty of this wondrous sea creature.
Getting to know the starfish
Despite the name, starfish are not really fish at all but actually belong to the marine animal category known as echinoderms. ‘Sea stars’ is considered a more appropriate name for these creatures. In general, they have a spiny surface on the top and a soft underside. They have tube feet with tiny projections on the underside. They do not have fins, scales or gills and their way of moving in the water is different from the way fish move. Fish use the fins and tails while the starfish use their tube feet.
Starfish belong to the Phylum Echinodermata and are similar to sea urchins, sea cucumbers and sand dollars. All of them have five sections in their body. Starfish come in a range of colors, sizes and shapes and do have the distinctive star shape that has earned them the name. There are around 2000 species of starfish.
Starfish are found around the world and they populate different depths and different temperatures of water. They are not found in fresh water.
Physical characteristics of the starfish
All the types of sea stars have a star shape but they do not have five arms necessarily. Some have as many as 40 arms.
If a sea star or starfish loses an arm, it can regenerate it. It is a useful defense mechanism because if a predator catches hold of an arm, the starfish can escape by leaving the arm behind. Given that the starfish’s arm contains some of the creatures’ vital organs, regenerating an arm is a really important survival factor for these creatures. It can take as much as a whole year for the regeneration to become complete.
The upper surface of the starfish with its tiny spines made of calcium carbonate serves as armor for the starfish. The spines protect them against attacks from other sea creatures such as otters and fish and also from birds.
A truly amazing detail about the starfish is that it has no blood and it has a water based vascular system. These creatures pump in sea water through a sieve plate and this helps extend the tube feet.
Starfish have an eye spot at the end of each arm. While these eyes are not capable of much complex vision they sense light and dark and this is very useful for these creatures which live typically in the ocean.
The tube feet of the starfish are useful for movement and for capturing prey. The tube feet filled with sea water enable them to move very quickly and they help grip and extract food from the prey such as mussels and clam.
The way the starfish eats is interesting. It has a mouth on the underside. However, given that many of the starfish’s preys have hard shells, the starfish starts off by catching hold of the prey with its arms. It cracks open the shell a little and then pushes out its stomach into the prey through its mouth. It digests the food in the prey and then pulls the stomach back into its own body. This is a unique digestive process that allows the creature to eat preys larger than itself.
Starfish, like many other creatures in nature, are a reminder of the wonders of the natural world. Instead of walking past these creatures, if we spend a few minutes to get to know some of these amazing starfish facts, we are left in awe of the complex engineering behind these apparently simple sea creatures.