Spotted on Ocracoke: The cannonball jellyfish

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By Peter Vankevich

In the last few weeks someone walking along Ocracoke’s beaches, especially at Springer’s Point, probably encountered numerous jellyfish on the beach or the intertidal zone.

These are cannonball jellyfish (Stomolophus meleagris), named in 1860 by famed scientist Louis Agassiz. Cannonballs also go by the names of Cabbagehead and Jellyball.

The species lives in estuaries and along coastal shorelines, preferring tropical to semi-tropical saltwater with a temperature range to 68 to 74 degrees Fahrenheit. Their life span is only three to six months.

In eastern North America, the primary range is from North Carolina south and especially the Gulf of Mexico. With unusual currents, they may occasionally stray into the waters as far north as New England and as far south as Brazil.

Cannonballs can be found in the eastern Pacific from California to Ecuador, and in the western Pacific from the Sea of Japan to the South China Sea.

The overall shape is that of a bell, or cannonball, which is how they get their name. They can grow to the size of a small cantaloupe and weigh up to two pounds.

Their color varies from overall clear to a yellowish wash with a rufous/brown ring at the base. Those in the Pacific are bluish. They feed by sucking water into the mouth fold when the bell contracts.

Although not considered to be stingers, one should refrain from touching them as they exude a substance in the mucous that can cause a burning sensation if it gets in the eyes.

Jellyfish are marine invertebrates that lack basic sensory organs or a brain and consist of about 95% water. They do possess highly specialized nervous systems that allow them to perceive stimuli, such as light and odor.

Since jellyfish are not fish, many people now refer to them as “jellies” or “sea jellies.”

Like other jellies, cannonballs may form large swarms, called “blooms,” consisting of hundreds or even thousands of individuals.

There is concern that these blooms are increasing and may indicate an imbalance in the ecosystem as they may be taking the place of fish that have declined in numbers.

Cannonballs are strong swimmers and move by pumping water through their 16 short arms, which are called “oral” because they are used for propulsion and catching prey, which consists primarily of zooplankton and the larvae stages of shellfish and red drum.

They cannot, however, move against wind-driven currents, and many will wash up on beaches during an onshore wind as have been seen recently.

Cannonballs have a much higher amount of protein than most other jellies which makes them a food source for humans as well as leatherback turtles and Atlantic spadefish.

In Asia, they are also used as a medicine, purportedly for combating maladies such as arthritis.

They are harvested in the waters off Florida, Georgia and South Carolina, and after a dehydration process are exported to China and Japan and other Asian countries where they are served primarily in soups and salads.

To play off “The Wizard of Oz,” for an animal with no brain, heart or bones, they, nevertheless, have an interesting story.