Blue Button, Porpita porpita
Blue Button, Porpita porpita. Collected of the surface by hand off Point Palmilla, Baja California Sur, May 2021. Size: 3.0 cm (1.2 inches) in diameter. Photograph taken at the time of collection with the animal being extremely fragile. Identification reconfirmed by Linsey Sala, Scripps Institution of Oceanography, La Jolla, California. Note: I have collected this species at the same location in May 2019; it appears that show up in local waters in May and then disappear for the rest of the year.
Phylogeny: The Blue Button, Porpita porpita (Linnaeus, 1758), is a member of the Porpitidae Family of Chondronophores. The Porpitidae Family consists of two genera – Porpita and Velella. There are two species in the Porpita Genus. Although the Blue Button is often referred to as a jellyfish, it is actually a colony of small animals known as hydrozoan polyps. They are known in Mexico as Boton Azul.
Morphology: The Blue Button has a flattened, round disk that is made up of multiple (up to 100) circular and radiating air chambers. The center of the disk may be golden brown, blue or whitish in color with blue or greenish edges. The tentacles may be blue, turquoise or yellow in color. The disk does not have a sail structure. Their tentacles are longer than those of the By-the-Wind Sailor, Velella velella. The tentacles are equipped with nematocysts (or cnidocysts) that deliver a toxic sting that they utilize to capture prey or repel predators. Blue Buttons reach a maximum of 5.0 cm (2.0 inches) in diameter.
Habitat and Distribution: Blue Buttons live on the surface of the open ocean. The Blue Button is found worldwide, in subtropical to tropical seas. The Blue Button is found in all Mexican waters of the Atlantic Ocean and Pacific Ocean.
Diet: Blue Buttons are predators that hunt and feed on tiny fish, copepods, larvae, and fish eggs. The intermediate ring of tentacles are for reproduction, and the inner tentacles function as both the anus and the mouth.
Predators: Blue Buttons are prey for sea slugs of the Glaucus Genus and gastropods of the Janthina Genus.
Reproduction: Individual Blue Button colonies are simultaneous hermaphrodites (having both male and female reproductive organs). Specialized polyps called gonozooids are responsible for reproduction. The gonozooids release sperm and eggs into the surrounding water. The fertilized eggs become larvae, which develop into polyps. The polyps divide and form new colonies.
Ecosystem Interactions: Porpita Porpita belongs to the neustonic, or ocean surface, food web. This species engages in a form of commensalism with juvenile Malabar Trevally, Carangoides malabaricus, which use the Porpita for shelter. Any type of parasitic or symbiotic relationship has not been formally documented.
Human Interactions: Blue Buttons can sting and cause contact dermatitis. Otherwise, they have very limited impact on human activities. From a conservation perspective they have not been evaluated, but are common with a widespread distribution and should be considered to be of Least Concern.
Synonyms: Acies palpebrans, Chrysomitra striata, Discalia primordialis, Disconalia gastroblasta, Disconalia pectyllis, Disconalia ramifera, Holothuria denudata, Holothuria nuda, Medusa porpita, Medusa umbella, Polybrachionia linnaeana, Porpita appendiculata, Porpita atlantica, Porpita chrysocoma, Porpita coerulea, Porpita forskahli, Porpita forskalea, Porpita fungia, Porpita gigantea, Porpita glandifera, Porpita globosa, Porpita granulata, Porpita indica, Porpita kuhlii, Porpita lutkeana, Porpita mediterranea, Porpita moneta, Porpita pacifica, Porpita radiata, Porpita ramifera, Porpita reinwardtii, and Ratis medusae.