Chrysaora hysoscella, (Linnaeus, 1767)
Chrysaora hysoscella, the compass jellyfish, is a common species of jellyfish that inhabits coastal waters in temperate regions of the northeastern Atlantic Ocean, including the North Sea and Mediterranean Sea. In the past it was also recorded in the southeastern Atlantic, including South Africa, but this was caused by confusion with close relatives; C. africana, C. fulgida and an undescribed species tentatively referred to as "C. agulhensis".
It is a true jellyfish displaying radial symmetry with distinct brown markings shaped like elongated V's on its bell. C. hysoscella adults are highly susceptible to the parasite Hyperia medusarum, but this has had no significant effects on the population. This organism has a benthic polyp stage before developing into a pelagic adult medusae. Compass jellyfish consume a variety of marine invertebrates and plankton and are preyed on by very few. C. hysoscella contribute to the global issue of jellyfish overpopulation which is concerning to humans for various reasons including recreational interference, economic turmoil for fishing communities, and depleted fish resources.
The compass jellyfish is found in coastal waters of the northeast Atlantic, including the Celtic, Irish, North and Mediterranean Seas. They inhabit these waters mostly at the top of the water column, and although they inhabit shallow water, they move up and down in the water column often ranging from surface waters to just above the seabed. They are rarely found deeper than 30 m from the surface.
Compass jellyfish are carnivores, consuming other marine invertebrates and plankton. They feed on a variety of benthic and pelagic organisms including but not limited to: dinoflagellates, copepods, crustacean eggs, larval fish, and chaetognaths. They stun and capture their prey with stinging cells on their tentacles. The oral arms facilitate movement of captured prey into the oral opening. Compass jellyfish have very few predators. They are known to be consumed by the leatherback sea turtle and ocean sunfish.
Like other Scyphozoans, Chrysaora hysoscella undergo metamorphosis as the organism develops and experiences a polyp and then medusa form. Females release planular larvae which swim to find a suitable place to settle. The planulae attach to a benthic substrate and develop into a sessile polyp which releases immature medusae through asexual reproduction called strobilation. Chrysaora hysoscella function as a male upon maturity and then develop female gametes, meaning this organism is protandrously hermaphroditic.
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