Carybdea is a genus of venomous box jellyfish within the family Carybdeidae that currently consists of a total of 8 species. This genus of jellyfish are often found in warm waters around the world in waters such as the Mediterranean Sea, the Pacific Ocean, and off the coast of Africa. Their sting can cause a range of effects depending on the species. These invertebrates will go through both sexual and asexual reproduction as they transform from a polyp to medusa. Carybdea have a box-shaped bell with four tentacles and eye-like sensory structures. There are distinct physical markings that differentiate many species within the genus. While Carybdea use their venom to act as predators, they are also preyed on by turtles and various fish. They feed on plankton, invertebrates, fish, and some crustaceans.
This genus of venomous box jellyfish is categorized in the class Cubozoa. Cubozoans are referred to as box jellyfish due to the fact that when viewing the transverse section of the bells they appear to be in the shape of a square. At each corner of the square, there are clusters of tentacles. A specific feature of the Cubozoan tentacles is their flatted base at the end of each tentacle.[3]
This genus of species can further be classified into the family Carybdeidae which requires the species to have four tentacles or four groups of two or three that are separately attached to its own unbranched Pedalium.[4]
The genus itself must have a few qualifications to fall under Carybdea. The stomach cannot be suspended from mesenteries, and the gastric cirri are found at the corners of the stomach or in crescentic areas.[5] The velarial canals, which are extensions of the gut, and have only 2-4 branches.[5] Currently, Carybdea is the only genus with Carybdeidae that has a distinct feature of a heart-shaped rhopaliar niche ostium with a single, upper covering scale and no lower scales.[6]
A recent study posed the question of whether or not the species C. marsupialis, found in Caribbean waters, is part of the genus Carybdea. The studies showed some differences that were concluded between medusae of C. marsupialis from two different locations, Mediterranean and Puerto Rico. This hypothesis is still under review.[6] Currently, there are 10 species fall under this genus.
Some species are widespread such as the species Carybdea sivickisi. This species can be found in temperate, tropical, and subtropical locations during the warmer months of the year for mating. More specifically, Carybdea sivickisi are commonly found in warm waters of the Western Pacific Ocean ranging from Japan to New Zealand.[8] Carybdea rastoni, another common species, is known to inhabit warm shallow waters. It is commonly found in the warm waters of Hawaii, Australia, Japan, and the Philippines.[9] Carybdea swim to deeper waters in search of food.[8]