SEA LILIES AND FEATHER STARS: Crinoidea

PHYSICAL CHARACTERISTICS

Sea lilies and feather stars are sea animals with five arms and a mouth that faces up. The main body part is the crown, which holds the mouth, digestive tract, and anus (AY-nuhs). The arms grow out of the crown. Sea lilies have a stalk below the crown and look like flowers. Feather stars have a cluster of tentacles below the crown and look like ferns. The arms of both animals usually have branches, as many as two hundred in some species. Each arm and branch has a food groove lined with grabbers called tube feet. The arms of sea lilies and feather stars are 0.4 to 14 inches (1 to 35 centimeters) long. The sea lily stalk is about 3.3 feet (1 meter) long. Feather stars are white, black, purple, red, green, brown, violet, or a combination of colors. The deeper the animals live, the paler is the color. Sea lilies are white.

GEOGRAPHIC RANGE

Sea lilies and feather stars live in the western part of the Pacific Ocean and on both sides of the Atlantic Ocean.

HABITAT

Most sea lilies live in deep water, and most feather stars live on coral reefs. Both animals usually live on hard surfaces.

DIET

Sea lilies and feather stars eat plankton and waste. Plankton is microscopic plants and animals drifting in water.

BEHAVIOR AND REPRODUCTION

Sea lilies and feather stars stand upright in the water current and extend their branches so that their food grooves can catch plankton. Feather stars usually live in clumps, attaching themselves to crevices and other places in which they can hide most of their body. Most species come out at night, exposing part or all of their arms, or even the entire body. Sea lilies also live in clusters but because of the lack of light in deep water do not have a day-and-night pattern of coming out.

Feather stars use their arms to crawl. Some swim by alternating their arms up and down. They go down through the water by extending their arms like parachutes. Only a few sea lilies can crawl, and none can swim.

Sea lilies and feather stars can regrow lost body parts. Feather stars can regrow their arms as long as at least one arm and a nerve center are intact. Sea lilies can regrow an entire crown.

Sea lilies and feather stars have separate sexes. The males release sperm into the water, and females of most species release their eggs into the water. In some feather stars, the eggs stay on the female for days and then are released into the water or enter pouches. After joining with sperm, the eggs of almost all sea lilies and feather stars develop into non-feeding, drifting larvae (LAR-vee), which are animals in an early stage that change form before becoming adults. These larvae transform into bottom-dwelling, non-feeding, stalked larvae that transform into bottom-dwelling, stalked young animals. The young are ready to reproduce in twelve to eighteen months.

SEA LILIES, FEATHER STARS, AND PEOPLE

Sea lilies and feather stars have no known importance to people.

BAD MANNERS?

Sea lilies and feather stars eat with their feet. The food grooves are lined with tube feet organized into groups of three. The two larger tube feet collect large food particles, fold over, and place the particles in the food groove. Smaller particles stick to mucus on the animal's arm, and the small tube foot brushes these particles into the food groove.

CONSERVATION STATUS

Sea lilies and feather stars are not considered threatened or endangered.

ORANGE SEA LILY (Nemaster rubiginosa): SPECIES ACCOUNTS

Physical characteristics: Orange sea lilies are feather stars with twenty to thirty-five arms that are 4 to 8 inches (10 to 20 centimeters) long. They are bright orange with a black stripe along the top of each arm.

Geographic range: Orange sea lilies live in the western part of the Atlantic Ocean from Florida to Brazil.

Habitat: Orange sea lilies live in shallow water attached to hard surfaces.

Diet: Orange sea lilies eat plankton.

Behavior and reproduction: Orange sea lilies hide their crown during the day, only the arms and branches showing. The entire body may come out at night. The males release sperm and the females release eggs into the water, where they join. The fertilized (FUR-teh-lyzed) eggs develop into larvae, which transform into young orange sea lilies, which mature into adults.

Orange sea lilies and people: Orange sea lilies have no known importance to people.

Conservation status: Orange sea lilies are not considered threatened or endangered. ∎

WEST ATLANTIC STALKED CRINOID (Endoxocrinus parrae): SPECIES ACCOUNTS

Physical characteristics: West Atlantic stalked crinoids (CRY-noyds) are sea lilies with a stalk less than 3.3 feet (1 meter) long. Each arm has eight branches. Hairlike fibers on a curved stalk anchor the lilies to the material on which they live.

Geographic range: West Atlantic stalked crinoids live in the Atlantic Ocean near Florida, the Bahamas, and Cuba.

Habitat: West Atlantic stalked crinoids live in water 500 to 3,200 feet (150 to 975 meters) deep. They anchor themselves to hard surfaces.

Diet: West Atlantic stalked crinoids eat plankton.

Behavior and reproduction: West Atlantic stalked crinoids wave their arms rapidly up and down to prevent other animals and undesired particles from settling on the crown. They move from place to place by crawling over the bottom using their arms. Scientists do not know how these sea lilies reproduce.

West Atlantic stalked crinoids and people: West Atlantic stalked crinoids have no known importance to people.

Conservation status: West Atlantic stalked crinoids are not considered threatened or endangered. ∎

FOR MORE INFORMATION

Books:

Carson, Rachel. The Edge of the Sea. 1955. Reprint, Boston: Mariner, 1998.

Niesen, Thomas M. The Marine Biology Coloring Book. 2nd ed. New York: HarperResource, 2000.

Web sites:

"Class Crinoidea." Palaeos. http://www.palaeos.com/Invertebrates/Echinoderms/Crinoidea/Crinoidea.htm (accessed on February 25, 2005).

Messing, Charles Garrett. "Introduction to Comatulids." Charles Messing's Comatulid Crinoid Page.http://www.nova.edu/ocean/messing/crinoids/w3introduction.html (accessed on February 25, 2005).