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Black sea nettle

Chrysaora achlyos

Not on exhibit
Animal type
Invertebrates
Ecosystem
Open ocean
Relatives
Other true jellies, sea anemones, coral
Diet
Gelatinous zooplankton including other jellies
Range
Mexico, southern Baja California, north to Monterey Bay (rare)
Size
Up to 3 feet (.9 m) and oral arms extending to 20 feet (6 m)

Meet the black sea nettle

The black sea nettle is considered a giant jelly; its distinctive purplish bell can reach over three feet (.9 m) in diameter. Its lacy, pinkish mouth-arms can reach nearly 20 feet (6 m) in length and its stinging tentacles can reach 25 feet (7.6 m) or more. They typically appear in large blooms in San Diego Bay—most recently in 2012.

Watch in real time

Natural history

The black sea nettle is an elusive creature; during most years its whereabouts are unknown. Scientists named this jelly in 1997, although pictures of the species were taken as early as 1926. Many details about its behavior, distribution and lifecycle remain a mystery.

A black sea nettle swimming in light blue water

This giant jelly has a distinctive purplish bell and long, lacy mouth-arms that can reach 20 feet (6 m). Its tentacles can extend even longer, reaching 25 feet (7.6 m) or more.

Close-up of a black sea nettle (Chrysaora achlyos) in the Open Sea exhibit.

Cool facts

  • The black sea nettle was the largest invertebrate discovered in the 20th century!
  • The black sea nettle provides the Pacific butterfish with food and protection. The silvery butterfish feeds on the plankton the jelly gathers. When danger approaches, the butterfish hides inside the jelly’s bell.

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