Stomolophus meleagris L. Agassiz, 1862, Atlantic Ocean, East Coast of United States.
OTHER COMMON NAMES English: Cabbagehead jellyfish.
The firm, almost spherical swimming bell grows up to 7 in (18 cm) in diameter and lacks tentacles. The oral arms are fused to form a rigid, short mound below the bell. The bell color ranges from nearly white to bluish, and it may darken to reddish orange with blue speckles toward the bell margin; the oral arms are white.
The cannonball jellyfish occurs in subtropical and tropical Atlantic and Pacific North American waters. It is abundant from North Carolina through the Gulf of Mexico. It also is found in
the Caribbean, in South America to northern Argentina, and in the Pacific from southern California to Ecuador.
The medusae are found in coastal waters in summer. BEHAVIOR
These medusae are strong swimmers. Within a group, individuals swim horizontally in the same direction, oriented with or against the wind and surface-wave or current direction.
The medusae lack obvious long feeding tentacles and oral arms, but they pump water containing zooplankton through the oral arms and elaborate filtering structures within the bell. There, minute tentacle-like projections with nematocysts catch prey. The medusae eat a variety of zooplankton prey, including mollusk veligers, copepods, tintinnids, larvaceans (= appendicu-larians), and fish eggs.
This species exhibits the typical life cycle of rhizostome scyphozoans, having both medusa (sexual) and polyp (asexual) stages. Only one or two ephyrae are produced per polyp.
CONSERVATION STATUS Not listed by the IUCN.
This is one of the 11 species of rhizostome medusae that are fished commercially for human consumption. This species has no stinging tentacles but produces mucus that is shed in strings laden with nematocysts that irritate skin on contact. They also act as a host for juvenile butterfish Peprilis species that depend on the jellyfish for protection. ♦
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