National Aquarium – Leidys Comb Jellyfish

Leidy’s Comb Jelly

Mnemiopsis leidyi


Comb jellies can make their own light (bioluminescence), and flash when disturbed.

Exhibit Name and Location:
Baltimore - Jellies Invasion: Oceans Out of Balance

Leidys Comb Jellyfish Leidys Comb Jellyfish

Leidy’s Comb Jelly

The comb jelly looks different from other jellies because it’s not made up of a bell and tentacles. Instead, it is a translucent walnut-shaped body with wart-like bumps. For this reason, it’s sometimes called a sea walnut. 

Comb jellies are translucent but refract light, appearing to have rainbow colors running down their bodies on the track of internal moving cilia. They can also make their own light (bioluminescence), flashing when disturbed.

Leidy's Comb Jellyfish Facts


Zooplankton, especially oyster eggs and larvae


Maximum size is about 5 inches long


Atlantic coastal waters from Cape Cod, Mass., to the Carolinas; invasive to the Black Sea

Population Status

In the past, jelly populations were kept in check by predators like sea turtles and jelly-eating fish. Due to the reduction of their predators, jelly populations are growing at alarming rates.


Sea turtles and other jelly-eating animals, such as tuna, sunfish, butterfish, and spiny dogfish, keep the jelly populations in balance. All seven species of sea turtles include them in their diets. The largest sea turtle species, the leatherback, depends on jellies for food. Because jellies are more than 90% water and an adult leatherback can weigh more than 2,000 pounds, one turtle can consume a lot of jellies. Additionally, Leidy’s comb jellies are the favored food item for the pink comb jelly (Beroe ovata), also native to Atlantic coastal waters.

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Jack Cover
General Curator

pressroom striped fish

As the general curator, Jack's role is to ensure that our living animal collections are thriving and diverse, to best exhibit the beauty of the wild habitats we represent here at the Aquarium. Learn More

A Note From the Caretaker

In addition to over-harvesting, comb jellies have been blamed for the decline of the once-over-abundant Virginia oyster in the Chesapeake Bay. The free-swimming oyster larvae hatch at the same time of year that the comb jellies flourish, so oyster numbers are reduced as comb jellies feast on their eggs and larvae. Thankfully, Atlantic sea nettles consume comb jellies in some Bay tributaries, giving oyster populations a chance.

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