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. 

Red Nobbed Starfish.  I think this is such an interesting creature.
Red Nobbed Starfish. I think this is such an interesting creature. | Source
Paracrinoid Fossil.
Paracrinoid Fossil.

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. 

Asterius Rubens

Common Sea Stars
Common Sea Stars | Source

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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Comments 26 comments

Donna Suthard profile image

Donna Suthard 5 years ago

great article! I like your photos

Pamela99 profile image

Pamela99 5 years ago from United States

The ocean creatures are interesting and I enjoyed your hub.

PR Morgan profile image

PR Morgan 5 years ago from Sarasota Florida

I love starfish...I see them all the time in the Keys...they stand out so much with their bright colors and they are really big!

CMHypno profile image

CMHypno 5 years ago from Other Side of the Sun

Really cool starfish picture! There are some really fascinating creatures in the sea, and I wonder how many are down there that we haven't discovered yet?

mannyrolando profile image

mannyrolando 5 years ago

Great hub and I really like that photo of the Red Nobbed Starfish!

Simone Smith profile image

Simone Smith 5 years ago from San Francisco

Oh, what fun! Excellent Hub :D

PhoenixV profile image

PhoenixV 5 years ago from USA

Great hub! Voted up!

chamilj profile image

chamilj 5 years ago from Sri Lanka

Really cool pictures of sea creatures. Voted up!

chloe 5 years ago

i think this is really cool and helpful.

qlcoach profile image

qlcoach 5 years ago from Cave Junction, Oregon

Yes to the the beauty of the sea and all its creatures. I live in Oregon and you can find me there on the coast searching the tidepools for starfish, sea urchins, and other treasures. Sending you blue butterflies and turquoise Light....Gary.

oceansnsunsets profile image

oceansnsunsets 5 years ago from The Midwest, USA Author

Donna, thank you!

Pamela, thank you, and so glad you enjoyed it. :)

PR Morgan, oh that sounds awesome. I hope to go there one day and see them myself. Big and colorful starfish sound so cool. I have to visit the keys sometime.

CMHypno, I totally hear you. I wonder myself about how many more things are there we don't even know about. What a fascinating world all its own! Glad you liked the picture, thanks for stopping by and commenting. :)

Manny, thank you very much!

Simone, thank you so much, I appreciate that, and glad you found it fun. :)

Phoenix, thank you!

Chamilj, thank you for the visit and comment and vote. :)

Chloe, thank you very much.

Qlcoach, that sounds very lovely! I would so love to visit the Oregon coast one day. What you described sounds like heaven to me! I would be there too any day if I could be. When I visit California, you can find me at my favorite tidepools there, so I understand. Loving the blue butterflies and turquoise light, thank you!

McKenna 4 years ago

Nice pic of the sea star do you know that all echinoderms have tube feet.

McKenna 4 years ago

I am home schooled and i looked this up

McKenna 4 years ago

Did you know that some sea urchins can walk on their spines using them a lot like stilts.

oceansnsunsets profile image

oceansnsunsets 4 years ago from The Midwest, USA Author

Hello McKenna, I am so glad you found this! :) Thanks for your comments and input. I really appreciate it. I liked hearing your extra facts you shared, it all is so fascinating to me. Have a great day!

McKenna 4 years ago

I know this stff cause i have a book called the swimming creatures of the fifth day.The book is for my home schooling class.So i think i need to tell you about my self.Well i am 9 years old and my last name is clevenger.And i wrote a new book about all the sea creatures that i have learned about.I read it to my little brother his favorite part is the part about sharks.And have a great day too.

McKenna 4 years ago

Did you know how sand dollars got their name. I will tell you how they got their name. Well back then there was no paper money all the money was in form of coins.A dollar was a huge silver coin the sand doller reminded people of these large coins so people started to call them snd dollars.I like this story!

McKenna 4 years ago

Thanks a lot for this web site i love the ocean so much even my room is a light blue color and it has fishes and star fish ans well every thing.


oceansnsunsets profile image

oceansnsunsets 4 years ago from The Midwest, USA Author

Hello again McKenna, I think its wonderful that you have such an interest in the ocean and sea creatures. I am the same way, and its amazing all that is in the ocean or from the ocean.

Good for you for putting what you learned into a book. I think its great that you read to your brother, and I am not surprised he liked the part about the sharks. Take care, and I wish you the best. :)

McKenna 4 years ago

Thanks i wish you the best too.I was not very surprised I know he would like the part about sharks.

oceansnsunsets profile image

oceansnsunsets 4 years ago from The Midwest, USA Author

McKenna, I posted some links above to my other articles that have to do with the ocean and ocean animals like birds and animals and plants in tide pools. You may find those interesting as well. I hope you always keep learning and that you always love the ocean and its animals as much as you do now.

McKenna 4 years ago

Okay thanks i will look them up.have a great day.

McKenna 4 years ago

I looked them up you are a good author.

oceansnsunsets profile image

oceansnsunsets 4 years ago from The Midwest, USA Author

Thanks so much McKenna. I wish you the best as you study all kinds of things in the future. I hope to do more ocean themed articles in the future, as I am able. It is a great subject to study! Take care. :)

Faishal 4 years ago

Amazing! this is so helpful for my homework! thanks:)

oceansnsunsets profile image

oceansnsunsets 4 years ago from The Midwest, USA Author

Hi Faishal, Thank you! I am so glad you liked this information and found it helpful to you. Thank you for reading and taking the time to comment my hub on these sea creatures.

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