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Sea Daisies: Concentricycloidea

Medusiform Sea Daisy (xyloplax Medusiformis): Species Account

Physical characteristics: Medusiform (mih-DOO-seh-form) sea daisies are circular and slightly inflated. The body is 0.4 inches (9 millimeters) across, including the spines around the rim. The spines are all one length: 0.002 to 0.003 inches (40 to 75 micrometers). The mouth frame has ten to thirty bones. Medusiform sea daisies do not have a stomach. Instead there is a thin, flexible sheet on the bottom surface of the daisy that is supported by the mouth frame.

Geographic range: Medusiform sea daisies live on the east and west coasts of New Zealand.

Habitat: Medusiform sea daisies live on sunken wood in deep water.

To move to new habitats, sea daisies use pulsing actions of their stomach or drift like parachutes. (Illustration by Barbara Duperron. Reproduced by permission.)

Diet: Medusiform sea daisies absorb dissolved nutrients from decomposing wood.

Behavior and reproduction: Scientists do not know how medusiform sea daisies behave. They have separate sexes and mate. The young develop inside the females.

Medusiform sea daisies and people: Medusiform sea daisies have no known importance to people.

Conservation status: Medusiform sea daisies are not considered threatened or endangered. ∎



Brusca, Richard C., Gary J. Brusca, and Nancy Haver. Invertebrates. 2nd ed. Sunderland, MA: Sinauer, 2002.


Voight, Janet R. "How to Study Animals in Habitiats You've Never Seen." In the Field (spring 2005): 16–17.

Web sites:

"The Echinoderm Phylum." University of Washington School of Aquatic and Fishery Sciences. http://www.fish.washington.edu/classes/fish310/PDF/echino.pdf (accessed on March 9, 2005).

Additional topics

Animal Life ResourceJellyfish, Sponges, and Other Simple AnimalsSea Daisies: Concentricycloidea - Physical Characteristics, Behavior And Reproduction, Medusiform Sea Daisy (xyloplax Medusiformis): Species Account - GEOGRAPHIC RANGE, HABITAT, DIET, SEA DAISIES AND PEOPLE, CONSERVATION STATUS