This post is about echinoderms, which are a type of marine wildlife. It aims to teach vocabulary to English learners while providing clear information about what echinoderms are, their physical description, and their habitat.
You will also find a list of echinoderms, including names, facts, and pictures. This information will help you learn more about animal subtypes and their marine environments.
List of Echinoderms
Names of Echinoderms
- Blastoid
- Brittle Star
- Crinoid
- Cystoidea
- Eocrinoidea
- Sand Dollar
- Sea Cucumber
- Sea Urchin
- Starfish
What Are Echinoderms?
The term “echinoderm” comes from Greek, meaning “spiny skin.” They are a major group of marine life found primarily on the seafloor. Most echinoderms are known for their limited mobility or slow movement.
Some well-known echinoderms include starfish, sea cucumbers, and sea urchins.
Physical Description
Echinoderms come in a wide range of colors. Many of them have five arms (or multiples of five) and are known for their radial symmetry.
Instead of an outer shell, most echinoderms have an internal skeleton (endoskeleton) made of calcium carbonate that lies beneath the skin. This internal structure often gives their skin a rough or spiny texture.
Habitat
Echinoderms can be found throughout the world’s oceans, always living on the seafloor. Some species live in shallow environments such as rock pools or the intertidal zone.
Many others live in much deeper areas of the ocean, including the abyssal zone. Scientists believe that some echinoderm species may still remain undiscovered because they live in deep and hard-to-reach parts of the ocean floor.
Echinoderm Names with Facts & Pictures
Blastoid
Blastoids are an extinct group of echinoderms, meaning none exist today. Scientists believe they first appeared around 540 million years ago and went extinct about 250 million years ago.
Although they lived long before humans, we have strong fossil evidence showing that they existed. Blastoids did not have arms for movement. Instead, they were attached to the seafloor by a stalk, which helped them stay in place while feeding.
Brittle Star
Brittle stars look similar to starfish but usually have longer and slimmer arms. They get their name because their arms can easily break off when threatened.
This does not mean they are weak. In fact, losing an arm is a defense mechanism that helps them escape from predators.
Crinoid
Crinoids are often easier to find as fossils than as living animals, but they are not extinct. While they were far more common in ancient oceans, some species still exist today.
They have five-fold symmetry, like starfish, but their arms are more feather-like in appearance. Crinoids have existed for about 490 million years, making them one of the oldest echinoderm groups still alive.
Sand Dollar
Sand dollars are often known as white, coin-shaped creatures found on the seafloor. However, they are not white when alive.
Living sand dollars are covered with tiny hair-like structures and can appear purple, red, brown, gray, or dark green, depending on the species. They turn white only after they die. Sand dollars must stay underwater, as they cannot survive long outside the ocean.
Sea Cucumber
Sea cucumbers may not look very impressive, but they are true echinoderms. They feed on plankton and algae using tentacles around their mouths to collect food.
They are commonly exported to many Asian countries, where they are used as both a delicacy and traditional medicine. However, their medicinal benefits are not widely recognized in Western countries.
Sea Urchin
Sea urchins are among the spiniest echinoderms, with sharp spines covering their round bodies. These spines act as a strong defense against predators.
They are often found near coral reefs and usually live in warmer ocean waters, some species in cold waters too. Sea urchins do not have a visible face, but their mouth is easy to identify on the underside of the body.
Starfish
Starfish are the most well-known echinoderms. They are famous for their incredible ability to regenerate lost arms.
If an arm is damaged or lost, many starfish can grow it back. This ability has attracted scientific interest, especially in the field of regenerative medicine. Starfish can also eat prey larger than their mouth by digesting food outside their body first.
