Did you know that a feather star is actually an animal? Although it looks like a plant, it still has all of the characteristics of an animal. A feather star is also known as a sea feather or a crinoid. This animal is classified in the phylum Echinodermata and is an invertebrate (an animal with no backbone). As you read on, you will learn more about this unique and fascinating creature that dwells beneath the sea. The main feature that people admire about the feather star is its long colorful feathery arms. They have about 10 arms that range from 2-4 inches (50mm-100mm). The whole animal is about 10-15 cm (hardly ever 20cm). The colors of a feather star are mainly pink, red, yellow, and orange, but it can be in different colors too. They usually have light colored pinnules, side branches that give it a feathery look. On the bottom of the creature, pale extensions are connected to the central disk called cirri. Cirri are used to crawl or cling on hard substrate, a layer of earth beneath the soil. There are usually 20-30 cirri, with the mouth and anus on the upper side. Feather stars have a “U” shaped gut. They are usually harmless around any animal.

 

With all of the feather star’s physical characteristics, what can it do to survive in its environment? They can hide in big objects like crevices and boulders from menacing predators. Because they are inconspicuous and hard to find it gives them an advantage. A feather star can sneak away by swimming and flapping its arms in a wave formation, or stay still like it had never moved before. If a body part is broken off or lost, it can regenerate its organ back into place. Feather stars are usually resting or eating on crevices, rocks, boulders, substrate, corals, sponges, and seaweed. When a feather star rests in place, its arms curl inwards towards the mouth. The arms spread open when they are swimming or catching food.

 

There are about 550-600 crinoid species worldwide, but most of them are found in the Atlantic Ocean, English Channel, North Sea, British Isles, Azores, and the Shetland Islands. Feather stars eat almost anything they can find beneath the sea. They are not big eaters though and prefer to eat small and microscopic animals or things. A feather star’s diet is phytoplankton/zooplankton, particles, single-celled animals, and suspended material in the water. They tend to get food by catching them with their lengthy, extended, feathery arms. They can even catch food while swimming. Although a feather star doesn’t look like a nutritious meal, there are still some hungry predators out there. Crabs and lobsters with powerful claws and fish with strong teeth can tear away every limb of this creature. Luckily, with the help of its colorful arms, feather stars can swim away in an alternate undulation to escape and hide silently in the crevices.

 

Did you know that some crinoids used to have a stalk (stem)? But with a stalk, it couldn’t escape from its predators (which made it an easy prey), and all it can do is nothing but get devoured. Over a long period of time, natural selection came into place. Now, stalked crinoids are only found in the deep waters (making it less vulnerable), and some of them evolved into species without stalks and are found in the shallow waters. The stalkless crinoids had cirri and then could swim gracefully beneath the depths of the vast sea.

 

Author: Andrew T

Date Published: 02/2008

 

Sources: Gale Group Inc. "Crinoidea." Novel Guide. 2004. Thomson Learning Inc. 24 Jan. 2008 . Jeffords, Jeffrey N. "Crinoid." 24 Jan. 2008 . Lilley, Jane. "Featherstars." 16 Jan. 2008 . Nouailhat, Anne B. "Antedon Bifida." 2005. 16 Jan. 2008 .

 

Photo Credit: Jeffrey N. Jeffords, http://www.divegallery.com/crinoid_blue.htm