Stomolophidae Family of Jellyfish
One Jellyfish of the Stomolophidae Family is included in this website:
Cannonball Jellyfish, Stomolophus meleagris. The sole member of the Stomolophidae Family of Jellyfish.
________________________________________________JTS, BH to modify below
Phylogeny: Jellyfish of the Stomolophidae Family, like coral polyps and sea anemones are in the phylum Cnidaria. This phylum is generally characterized by animals having radial symmetry. Their bodies consist of an inner layer (endoderm) and an outer layer (ectoderm) with the layers separated by a jelly-like mesoglea. All Cnidarians have nematocysts (stinging cells) that they use to capture food. Stomolophidae Jellyfish are in the subphylum Medusazoa and the class Scyphozoa. Scyphozoans spend most of their life cycle in the medusa (bell or umbrella shaped) form. These bells can be fairly large and are often colorful. As Scyphozoans, these jellyfish lack a vellum, a shelf-like structure around the inside margin of the bell, and, usually, lack a ring canal, a canal lined with gastrodermis that runs around margin of bell. Stomolophidae Jellyfish are in the order Rhizostomae, the suborder Dactyliophorae, and the superfamily Rhizostomatoidea. The Stomolophidae Family is one of two families in this superfamily. The Stomolophidae Family is very small and contains only one genus and two species. The name Stomolophidae comes from the Greek words meaning “mouth” and “crest”, referring to the unique mouth structure of these jellyfish.
Morphology: Stomolophidae Jellyfish have a dense hemispherical bell. They lack the tentacles found along the margins of the bell that are found on other Scyphozoa jellyfish. They have eight fused oral arms hanging below the bell. These oral arms are complexly branched, with secondary mouth folds (scapulets) covered in mucus. They lack a central mouth, and instead, have these multiple “mini-mouths” located on their oral arms. The two species in this family are distinguished from each other by having distinct grooves and lappets around the margin of the bell (Stomolophus fritillaria) versus a smooth margin (Stomolophus meleagris). Individuals in this family may be bluish, white, or yellowish in color, often with brown around the margin. The largest specimens in this family reach around 25 cm (10 inches) in bell diameter.
Habitat and Distribution: Stomolophidae Jellyfish are found near the surface in open water, usually at depths less than 65 m (213 feet). While they are strong swimmers, they are sometimes pushed ashore in large numbers by strong winds or currents. Stomolophidae Jellyfish are found in the subtropical to tropical Pacific Ocean and the Western Atlantic. Both species in this family are found in Mexican waters.
Reproduction: Reproduction of the Stomolophidae Jellyfish occurs both sexually and asexually through an alternation of generations like other schyphozoans. Sexual reproduction involves the release of sperm out of the mouth of one animal and into the mouth of another. The embryo develops quickly in specialized pouches on arms near the mouth and within three to five hours larvae fall to the ocean floor and attach to a substrate. Here, they metamorphosize into a scyphistoma, the sessile polyp form, that catches small passing prey. During the asexual phase of reproduction, the polyp will undergo segmentation and metamorphosize again, becoming a swimming ephyra and eventually turn into adult jellyfish.
Ecosystem Roles: Stomolophidae Jellyfish are suspension feeders that feed by trailing their oral arms through the water and when prey is located, the nematocysts are triggered and the envenomation paralyzes the prey. They feed on crustacean larvae, fish larvae, mollusk larvae, other zooplankton, and fish eggs. In turn they are preyed upon by crabs, fish, including the Ocean Sunfish, Mola mola, and sea turtles. Stomolophidae Jellyfish host crustaceans and fish in commensal relationships.