No sting attached

4 raft hydroid banner

Commonly known as sea-money, Porpita pacifica is a blue-fringed disc of roughly 4 centimeters in diameter. This is a species of raft hydroid, a surface dwelling species which uses trapped air to control its buoyancy. While it may appear to be a single organism, P. pacifica is in fact a colonial animal, where a number of cooperative polyps live together under a raft-like structure. Interestingly, although a colonial animal, all the individual polyps function physiologically as one. Under the central disk a single oral opening ingests most of the food, which is primarily microplankton but also includes copepods (small crustaceans). Reproduction is attained by releasing tiny medusea into the water which will develop new colonies. Thankfully, this specie’s sting is too mild to be felt by humans.

Written by: Minke Witteveen

For more reading:
• Bieri, R. 1970. The food of Porpita and niche separation in three neuston coelenterates. Publications of the Seto Marine Biological Laboratory XVII: 305-307.
• Bridges, L. Unknown. Porpita pacifica. The Encyclopedia of Life. <>. Downloaded on 02 September 2015.
• Noble, A. 1963. Association between the fish, Caranx malabaricus Cuv. & Val. and the siphonophore, Porpita pacifica Lesson. Journal of Cetacean Research and Management 5: 131-139.

Related Posts