Echinoderms might not be a term you’ve heard of before. It is about a certain type of marine wildlife and is a great little tidbit of knowledge to learn about when you want to start showing how much you know about animal subtypes and their habitats. We’ll be covering what echinoderms are today, where they’re usually found, and any interesting facts that we can find about them too.
What Are Echinoderms?
The term echinoderm actually derives from the Greek meaning “spiny skin”. They are a major group of marine life and they are usually always found on the seafloor due to their lack of ability to move effectively. Some creatures that can be considered echinoderms include starfish, sea cucumbers, and sea urchins.
They come in a wide range of colors and many of them have five arms (or multiples of five) and are known for their radial symmetry. Most echinoderms also have a shell that is made of calcium carbonate and it completely covers their skin.
Echinoderms can be found just about anywhere in the ocean depths, but always on the seafloor. They can be found to thrive in something as small and simple as a rockpool or the intertidal zone. However, countless species of echinoderms can also be found in the much deeper parts of the ocean, known as the abyssal zone, and it is believed that some remain entirely undiscovered because they tend to live on the ocean floor.
List of Echinoderms
Names of Echinoderms
- Brittle Star
- Sand Dollar
- Sea Cucumber
- Sea Urchin
Echinoderms | Facts & Pictures
Blastoids are actually an extinct form of echinoderm (none exist today). It is believed that blastoids began their life 540 million years ago and went extinct about 250 million years ago. Naturally, this was way before the time of man, but we have plenty of fossil-based evidence that shows us that they existed. They don’t have any appendages that you utilized but instead attached themselves to a stalk on the ocean floor to keep themselves stationary while they feed.
Brittle stars are similar in appearance to starfish, though they are often much slimmer in the arms. They were given the name brittle star because when they are picked up their limbs often fall off. However, this isn’t because they’re fragile, it’s actually a defense mechanism to try to deter predators.
It’s believed to be more likely that you’d find the fossil of a crinoid today before you’d manage to find a living one. They are incredibly hard to come by and have died out over the years. They have 5 fold symmetry, just like a starfish but are more feather-like in appearance, rather than the hardened spine you see in a starfish. They are also ancient – about 490 million years they’ve been around now and they’re still going!
Sand dollars are fairly commonly known as those white-colored shell-like creatures that you can pick up on an ocean floor. However, they aren’t white when they’re alive. They’re actually more purple or red in hue and it’s only after they die that they take on the white color. They also need to stay submerged underwater, as they won’t survive long outside of it.
Sea cucumbers might not look like much, but they are an echinoderm just like any other on this list. They actually feed on plankton on algae with a bunch of tentacles that surround their mouths to pull them in. They’re also a common export to Asian countries, where they’re used as both delicacy and medication, though their benefits haven’t been discovered in Western countries.
A sea urchin is perhaps the spiniest of all the echinoderms, with countless spines surrounding its small body to act as a powerful deterrent and defense mechanism against predators. They are most commonly found near coral reefs and only inhabit warmer ocean waters. It is impossible to find a face on a sea urchin, but the mouth is easy enough to identify.
The most common of all the echinoderms. Starfish indeed have regenerative capabilities like no other marine life. They can regenerate their arms when they fall off, which has given scientists an interesting idea for using their cells in regenerative medicine. They also eat food that is too large for their mouth by first beginning to digest it outside of their own body!