Phylum: EchinodermataPhylum: Echinodermata

The Spiny-skinned AnimalsThe Spiny-skinned Animals

Class: Crinoidea: Ex. Crinoids

Crinoids (Class: Crinoidea) were very common inhabitants of the warm, shallow seas that once covered what is now Ohio. Fossils of their stems are extremely abundant around Cincinnati. Rarely, a whole crinoid fossil will be found locally. Entire specimens are in the limestones around Brookville Lake.

stem

Stem in cross section

stem

This is a Sea Lily. A living species of crinoid. Very few species remain. Most are brightly colored and they live in tropical seas. This species is from the Caribbean.

Sea lilies stretch out their arms to capture passing plankton for food.

Sea Lily – Tunicate Cove, Belize

Class: Asteroidea

As a child you probably grew up calling this a starfish. It isn’t a fish. It isn’t even closely related to a fish and it certainly isn’t a star. It is more appropriately called a sea star.

Most people picture sea stars as brown or tan animals. This is true only for those species that live on sand. Species that live on coral reefs are often cryptically colored to blend with sponges and polyps.

https://www.youtube.com/watch?v=HPhAGyDceLo

Tube feet video

Sea stars come in a diversity of sizes, shapes, and colors. This is a bat star. The name originates from the skin stretched between the arms like a bat’s wings.

Sea stars come in a diversity of sizes, shapes, and colors. This is a bat star. The name originates from the skin stretched between the arms like a bat’s wings.

Most sea stars are predators that use their water vascular system and tube feet to pry open bivalve mollusks.

These photographs show the diverse colors of sea stars as well as the fact that some species have more than five arms.

These photographs show the diverse colors of sea stars as well as the fact that some species have more than five arms. Those with more than nine arms are called Sun Stars.

Brittle stars have long, stringy arms. They move by walking with their arms. Their tube feet are like cleats to provided added traction.

https://www.youtube.com/watch?v=I-F4JQsfOzY

Brittle star locomotion