Echinoderms - Some Interesting Facts about these Cool Sea Creatures
Echinoderms are a marine group of invertebrates and are rather interesting to learn about. I simply love the ocean and enjoy learning all I can about it. These little sea creatures play their part in the bigger scheme of things and can be quite interesting, odd and even beautiful. The name comes from the Greek word for hedgehog skin, oddly enough! You may wonder what some examples of echinoderms are. Everyone has heard of a starfish, and they fit into this group. Other examples are sea cucumbers, sea urchins, feather and brittlestars and more.
Some key things to look for when identifying an echinoderm is that there are radiating body parts. This is why we see shapes like stars, or disks or spherical shape. Every one of them has calcium carbonate plates under there skin. This is what makes up its skeleton. It was interesting to find out they have little "canals" filled with water inside. This is called a water vascular system, and it is what enables these creatures to move around and do what they need to do to live and survive. It is also their mechanism for eating and breathing. I find them just fascinating the more I learn about them.
You will usually find echinoderms to be bottom dwellers of reefs, shores and the seabed. Its a treat to see them elsewhere on occasion though too. I love to see them on the supports of piers like Balboa Pier in Southern California. There are some very beautiful colored starfish along there when the tide is low.
What is an Echinoderms Defense against Predators?
In the circle of life, everything wants to eat or gets its nourishment so it can survive. Therefore, echinoderms are rather tasty to some other creatures assuming they can be broken open to get inside. Fish love to eat sea urchins for instance, if they can get into them. Different sea birds and sea otters also love to eat sea urchins. This is where the long sharp spines can be very helpful to an echinoderm. These sharp stinging spines are on ball and socket joints of echinoderms so they have a free range of motion as needed. Its an unpleasant weapon for the would be predator to stumble upon. Perhaps it is just enough to cause enough effort and pain for another creature to try something different to eat.
The danger in using these defense mechanisms is that they can break off and embed themselves into the other animal. This leaves that creature with a nasty wound. Some spines on some echinoderms are filled with venom. Have you ever heard of a crown of thorns starfish? This is one such example of venomous parts which are used to defend against hungry predators. Some can sting humans as well.
One of the more interesting ways an echinoderm can defend itself is found with creatures like the sea cucumber. They may seem defenseless as they have no spines or stingers or even protective plates, but they are not defenseless. When a sea cucumber is attacked, it sometimes will "eviscerate" (for lack of a better word) their guts or other internal organs which acts as a decoy to a hungry predator. Its ok however, because they can grow them back later on, and grow them even larger than they were before. Isn't that just wild?
A different kind of tropical sea cucumber can put out some sticky white threads which are rather strong. They are strong enough for an attacking crab to get tangled up in and it is thus restrained from further harming it. These white threads are called Cuverian tubules.
The brittlestar has its own defense mechanisms. They can lose an arm in an attack and thus break free and live on.
There is a wide range of feeders among echinoderms. Some are voracious predators, while others are peaceful grazers. Some use a filter feeding system.
There is a carnivorous kind of starfish that literally extends its stomach over the thing it wants to eat. They can digest it externally from this position, which sounds rather gross.
Most sea urchins are just grazers which scrape the surface of rocks with interesting looking little teeth, which look like the parts of a drill.
Sea Cucumbers use a sort of vacuum system, cleaning up organic debris and mud. As you can imagine, this shows us how the sea cucumber performs an incredibly important function, by cleaning up the sea bed. Isn't nature amazing?
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