Porpita porpita, commonly known as the blue button, is a marine organism consisting of a colony of hydroids found in tropical and sub-tropical waters of the Pacific, Atlantic, and Indian oceans. It is a unique kind of jellyfish, and blue buttons are part of the phylum (Cnidaria), in the class Hydrozoa.
The blue button lives on the surface of the sea and consists of two main parts: the float and the hydroid colony. The hard golden-brown float is round, almost flat, and about one inch wide. The hydroid colony, which can range from bright blue turquoise to yellow, resembles tentacles like those of the jellyfish. Each strand has numerous branchlets, each of which ends in knobs of stinging cells called nematocysts. The blue button sting is not powerful but may cause irritation to human skin.
The blue button itself is a passive drifter, and is part of the neustonic food web. It is preyed on by the sea slug Glaucus atlanticus (sea swallow or blue glaucus) and violet sea-snails of the genus Janthina. It competes with other drifters for food and mainly feeds on copepods and crustacean larvae. The blue button has a single mouth located beneath the float, which is used for both the intake of prey and the expulsion of wastes.
- WoRMS (2011). "Porpita porpita (Linnaeus, 1758)". In P. Schuchert. World Hydrozoa database. World Register of Marine Species. Retrieved 2011-12-18.
- "Blue Buttons in Florida."
- Meinkoch, Norman. "The Audubon Field Guide to North American Seashore Creatures." 1981. New York, New York.
- see distribution at the Encyclopedia of Life
- "Identification Chart for Jellies."
- Hayward P.J. & Ryland J.S. (1990). The Marine Fauna of the British Isles and North-West Europe. Volume 2 - Molluscs to Chordates. page 681. Clarendon Press, Oxford. ISBN 0-19-857515-7
- Bieri, R. 1970. The food of Porpita and niche separation in three neuston coelenterates. Publications of the Seto Marine Biological Laboratory 17 (5): 305-307.
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