The Atlantic sea nettle forms mutualistic symbiotic relationships with the blue crab in the open ocean. The Atlantic sea nettle provides food and shelter for the blue crab, and the blue crab removes parasites and debris.
  • Size

    Ranges between 4.0 (10 cm) to 9.8 (25 cm) inches in diameter
  • Diet

    Zooplankton, comb jellies, copepods, mosquito larvae, fish eggs, and small fish
  • Range

    Atlantic Ocean from Cape Cod to Brazil, Indian Ocean, western Pacific
  • Habitat

    Estuaries, bays and open ocean

Physical Characteristics

  • Size varies by geographic location.
    • Dome-shaped body of middle Chesapeake Bay and estuary populations may measure almost four inches (10 cm) in diameter. Body of outer bay and estuary populations range between 5.1 to 9.8 inches (13-25 cm) in diameter.
  • Coloration of dome, or “bell”, in south Chesapeake Bay and open ocean populations is pink to maroon with red stripes radiating from the center of the bell. Stripes may extend down to the yellow tentacles.
  • Bell coloration in low salinity, estuary and southeast United States populations outside the Chesapeake Bay is white with no radiating stripes down the bell or tentacles.
  • Bell is saucer-shaped with lappets: shallow lobe-like structures formed by scalloping of the bell margin.
  • Thin, flowing tentacles may extend downward up to 19.7 inches (50 cm) from the bell margin. Four long, thick ribbon-like oral arms extend downward from the middle of the bell.

Animal Fact

Unlike most jellies, the Atlantic nettle can survive in low-salinity water.

Diet / Feeding

  • Carnivore; diet consists of zooplankton, comb jellies (Mnemiopsis), copepods, mosquito larvae, bay anchovy eggs, young minnows and small fish.

Range / Habitat

  • Occurs in the Atlantic Ocean from Cape Cod in the United States, south to the Gulf of Mexico, Caribbean and Brazil. Also occurs in the Indian Ocean and Western Pacific.
  • Found in brackish estuaries, low-salinity bays and high-salinity open ocean.
    • Most abundant in the Chesapeake Bay and its tributaries between May and September.

Reproduction & Growth

  • Polyps reproduce asexually. While the medusa is able to reproduce sexually.
  • During sexual reproduction the female will hold unfertilized eggs in the oral arms around the mouth. The male will release sperm into the water which the female will then bring to the eggs using both oral arms and tentacles.
  • Fertilized eggs will remain on the female’s oral arms until they develop into larvae called
  • Eventually the planulae will drop from the female’s oral arms and swim freely, searching for a suitable substrate to attach to.
  • Once a suitable substrate has been found, the planulae become known as sessile planocysts. In this stage the planocysts have their tentacles facing outward in order to filter feed.
  • After attaching to substrate, the planocysts begin the asexual portion of their lifecycle.
  • Environmental conditions are a key factor in determining if the planocysts go through one of two reproductive phases, either asexual or sexual.
  • If the asexual reproduction phase takes place the planocysts will bud off non-motile clones. If the sexual reproduction happens a phase called strobilation will occur. Strobilation only happens when the water quality, temperature and salinity are favorable and food supply is adequate.
  • Miniature medusa-like structures called strobilia form on a stalk, stacked one on top of the other with the most mature on top. The strobilia bud off as individual eyphyra. The eyphyra develop into the adult medusa.

Conservation Status

  • “Not Evaluated” on the IUCN Red List.

Additional Information

  • Open ocean populations form a mutualistic symbiotic relationship with blue crabs. The jelly provides shelter and food for the crab, and the crab cleans the jelly of debris and parasites.
  • Juvenile spider crabs can be found feeding on the jelly’s mucus and tissue, harvest fish will seek shelter in the tentacles and nudibranchs (Cratena pilata) will harvest potent nematocysts from polyps to use for their own defense.
  • Main predators include leatherback sea turtles, ocean sunfish and other species of jelly.
  • Unlike most jellies, the Atlantic nettle can survive in low-salinity water.
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