Crinoids are Echinoderms (members of the Phylum Echinodermata, meaning "spiny skin"). Crinoids are among the most ancient and primitive of ocean invertebrates.

There are both fossil Crinoids which date very far back in history AND modern Crinoids, which are also called Sea Lilies and/or Feather Stars (we will call them all Crinoids herein). The Crinoids are comatulids. These which often very colorful creatures which are harmless.

Crinoids are animals, not plants as some may think upon viewing them. Most are tied to the floor of the ocean upon some solid thing, with what is called a "hold fast" or anchor grown to the object to which it is fastened to keep it from drifting.

Here is an eART SCAN of
a Holdfast which washed
up on the beach at Fort
Lauderdale, Florida

Crinoids obtain food by extending their arms, which may look like feathers, to latch onto pieces of plankton or detritus (waste matter) passing by in the current. Hence, Crinoids are suspension feeders. The feeding is carried out by very small fingerlike tube feet, which line the feather like arms or tentacles, and collect the pieces of plankton or detritus and convey them into special food troughs or gutters which run in the center of each arm. Microscopic cilia carry the plankton or detritus, which is their food, along these trough floors and into the Crinoid's mouth

Crinoids are one of the things which divers most admire, because of their diversity and their beautiful and bright colors., but few pause to look closely enough to see they are host to a number of The ability of these creatures to master the art of disguise is amazing.

However, the diver's may not notice the tiny commensal animals, which live in and around the Crinoids, such as shrimp, clingfish, and squat lobsters. Trying to photograph many of these tiny commensals on a crinoid is difficult, as they want to hide and are difficult to get them to stay in position long enough to be filmed.

The number of arms on a given species of Crinoid may vary widely. The number may run up to 200 and be almost 14 inches in length. One interesting thing about Crinoids from other echinoderms is that they mouth is pointed upward, whereas the cousins the starfish, brittle stars and others have their mouths downward. Worldwide, there are nearly 550 species of comatulid crinoids.

The animals called comatulids are members of the Class Crinoidea, along with sea lilies (similar to comatulids but with long stalks). Collectively, comatulid crinoids and sea lilies are referred to as crinoids, since they are both members of the Class Crinoidea. Comatulids are most frequently labeled simply as crinoids or "feather stars".

Crinoids have always been a favorite of your PMNS Curator. I first became aware of them as crinoid stems found in the gravel in the driveways in Austin, Texas. I was curious where these round little pieces of limestone looking material with circles around them came from and what they were. All I knew for years was that they were called "crinoid stems".

Later when I became interested in fossils and paleontology, I learned that they the "crinoid stems" were actually part of an animal and that they had heads and arms and other body parts. I learned that the 'crinoid stems" were but parts of a long stem which held the crinoid upright from the "hold fast" and that they started life as a free-floating larvae.

Texas King Crinoid
found by David Wolf at
Brownwood Lake
Spillway in 1999
Four species of
Crinoids on one plate
purchased by TWP and
on loan to the PMNS
Three species of
Crinoids on one plate
From the collection
of Prof. Robert Cross
Crinoid Exterior
showing arms
Crinoid Interior
showing Anal tube
and other internal parts

More pictures of crinoids are being added shortly to this page.