Comb Jellies

Comb jellies have transparent, jelly-like bodies with bright, iridescent bands of color. The bands are made up of tiny hairs called combs, which divide the body into eight symmetrical areas.

Unlike jellyfish, comb jellies do not have stinging tentacles.

What species of comb jellies live in the Bay?

Two species of comb jellies can be found in the Bay:

• The sea walnut, Mnemiopsis leidyi, has a colorless, walnut-shaped body that grows to about four inches. Two of the body lobes are longer than the rest.
• The pink comb jelly, Beroe ovata, is often tinted pinkish to reddish-brown. Its sac- or egg-shaped body grows to about 4.5 inches.

Where do comb jellies live?

Comb jellies swim using their combs, which beat rhythmically to push the animal forward. When water conditions are rough, comb jellies will stay in deeper waters.

• Sea walnuts are the more widely distributed of the two species, occurring as far north in the Bay as the Baltimore area. They are present year-round but are most common in spring and summer. They often swim in large swarms.
• Pink comb jellies can be found in late summer and fall in the middle and lower Bay, south of Kent Island.

What do comb jellies eat?

Comb jellies are voracious feeders of planktonic organisms and small, spiny fish. They have been known to comsume almost 500 copepods per hour! Comb jellies eat by continuously pumping water into the cavity of their rounded bodies.

How do comb jellies reproduce?

Unlike jellyfish, comb jellies develop without distinctive larval and polypoid stages. The two comb jelly species are difficult to distinguish from each other when they are young.

Other facts about comb jellies:

• Comb jellies will easily break apart when taken out of water. If you find a comb jelly and would like to view its true shape, gently scoop it out of the water with a clear container and view it through the sides of the container.
• When disturbed at night, the jellies' combs will glow a soft green color.
• Even though they are both comb jellies, the pink comb jelly is actually a predator of the sea walnut.
• While sea nettles and other stinging jellyfish are more well-known to humans, comb jellies are much more abundant in the Bay.