photo by Teddy Hartanto
Latin Name: Stomolophus meleagris
Species: Marine Invertebrate
Conservation Status: Not Evaluated
The cannonball jelly has a domed pink or blue milky-colored bell with a brown band around the edge that can reach 8 inches wide. This jelly does not have tentacles around the edge of the bell, but rather mouth folds and short oral arms forming a chunky cluster beneath the bell. These jellies do not sting humans. Jellies lack a brain, heart, blood, and bones, but have a simple nerve net to detect light and other stimuli.
Range & Habitat (map)
Cannonball jellies can be found near shorelines in saltwater and estuarine habitats from North Carolina to Florida, as well as in the West Indies and Caribbean.
Diet
Cannonball jellies primarily feed on zooplankton, including larval oysters, other mollusks, and larval fish.
Life History
Jellyfish reproduce sexually and asexually at different phases in their life. As an adult (medusa stage), males release sperm into the water which are then captured and fertilized by females. Soon after, they detach as free-swimming, flattened larvae and seek a firm surface on which to attach. At this point, they develop into their polyp stage, with a mouth and tentacles that resemble a sea anemone. During this stage, the jelly can asexually split into many identical segments that will separate to become individual medusa forms. Adult cannonball jellies typically only live 6 months.
Significance
Cannonball jellies are the most common jelly seen on our beaches. They have symbiotic relationships with several other marine species, including fish and spider crabs that use their bell for protection and feed on zooplankton found in or on the jelly. These jellies are also an important food source for the leatherback sea turtle, which is facing population declines.
Threats & How You Can Help
Jellies’ dependence on zooplankton as a food source makes them vulnerable to events that harm these populations, such as algal blooms and pollution. As international demand for jellies increases, the potential development of commercial fisheries would have to take into account any impacts on local population stability. The use of Turtle Excluder Devices (TEDs) during shrimp trawls also aids cannonball populations, as they prevent jellies larger than 4 inches from getting caught in nets.