Echinoderms are a particularly different class of living beings. These are usually found in the deep oceans. If we go by the facts on Wikipedia, then this category of living beings further has around 7000 species listed in this category. Thus, knowing and understanding various types of echinoderms is a confusing task.

The various types of echinoderms have the fascinating feature of organ regeneration as well. Also, their skeletons ossify to form major limestone deposits. One surprising fact is that thought 7000types of echinoderm species are known today, but over 13000 are already believed to have become extinct.


Types of Echinoderms

Before understanding the various types of Echinoderms lets first dwell into the various categories under which these echinoderms are further classified. These categories are:


1) Holothuroidea

More commonly known as Sea Cucumbers, these echinoderms have no arms on their bodies. Also, they have a respiratory system unlike all other classes of echinoderms.

Their tentacles thus help in capturing the food which is essential for their growth. The stomach is their regenerative organ.


2) Asteroidea

Sea Stars or the pretty starfishes belong to this category of echinoderms. Their regenerative organs are their arms. The creatures in this category are usually predators and reside in shallow water near the ocean bed. They use their tubular feet for movements. The various examples of this category are Coral Crab, Harlequin Shrimp, and the  Triton Shorn. Also all kinds of starfishes including a venomous crown of thorns starfish fall into this category.


3) Echinoidea

This category of Echinoderms has around a hundred species under it. They generally have no arms. Their special feature ins the teeth in their mouth which help the in scraping off food from rocks as well. The best example of this category is the Sea Urchins.


4) Ophiuroidea

Their arms are distinctively visible from their head. These arms have no suckers and are flapped for movement. The examples of this category are brittle stars, Serpent Stars, and basket stars.


5) Crinoidea

With around 100 subspecies this category has echinoderms which have not only five but many more tentacles or arms. These are known to be the oldest known echinoderms and are inhabitants of really deep ocean beds. Its examples are the feather star and the sea lilies.


Echinoderms Edible or Not

The next question that arises is ARE ECHINODERMS EDIBLE?


Yes, echinoderms are very well edible. They are believed to be highly nutritive too but, no concrete studies have been conducted to establish their exact nutritive value.


Sea Urchins and Sea cucumbers are a part of many delicacies in Korea and Japan while in certain parts of the world they are still consumed as exotic dishes and are on menus of only fancy restaurants.

Sea urchins are usually called Uni in fancy delicacies. Japanese people also often consume fried starfish. All the echinoderms which are sold in markets for consumption purpose are safe and nontoxic.

But, it is advised that you should only consume echinoderms purchased from shops as certain echinoderms are toxic and can cause health hazards. Thus, do not ever consume echinoderms if you have netted them during a fishing spree, as they might as well be the toxic ones.


Fascinating Facts

Apart from all this, you should also be accustomed to the five majorly surprising characteristic features about echinoderms which indeed will be informative and hard to believe on.


1) The echinoderms have no blood. Yes, they have no blood. It is hard to believe but true. The oxygen in such cases is transported through the water-based vascular system.


2) They do not consume food from their mouth rather they eject their stomachs out of their bodies on to the food they wish to consume. The stomach then releases its digestive juices on the food and then the stomach is pulled back into place before the food is engulfed in the body.


3) Another cool feature to be added is that echinoderms though are living creatures but have no eyes. Imagine traveling all the way on the seabed without eyes. It is known that echinoderms have spots which recognize faint light and these are called eyespots. Eyespots are light sensitive but do not give any picture of the object emitting or absorbing the light.


4) The astonishing facts don’t end right there. The echinoderms have no brain and believe you in me they do not have any brains. Yeah, that could be the reason that people often use idioms and phrases where dumb is often compared to starfishes which are a category of echinoderms.


5) Regeneration is a common characteristic of echinoderms. The most common one being of the starfish’s ability to regenerate. The bodies of the echinoderms are usually symmetrical radially. You’ll be startled to know that starfish or brittle star cannot regenerate their arms but also certain internal organs too. Not only the regeneration will occur on the site were the organ has been lost but, the cut off part will in itself grow into a separate creature of the same species. Thus, if a limb of starfish is cut off, you will end up getting two healthy starfish as and when the regeneration process is over.


Though no proof exists it is also said that sea cucumbers which are known to grow only in salt water will burst if they are placed in fresh water. These facts were no less startling for us as well.

Also, though not quite a feature but sea urchins often splurge out their internal organs to feed the predator which attacks them as they can regenerate their internal organs again and this helps them save their lives. Well, for a no-brainer it does seem a pretty heavy task to perform.



Indeed, nature is a wonderful gift, and no one but God could have created such diverse organisms. It is hard to believe that animals without eyes, brain and also blood do exist and we humans even consume them. So, those of you who have had the opportunity to consume this class of living beings called the echinoderms, kindly share your experience with us and other readers in the comments section below.

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