Text Size: A  A  A

Comb Jellies

Sea walnuts have a colorless, walnut-shaped body. Two of the body lobes are longer than the rest. (Steven G. Johnson/Wikimedia Commons)
{photos} {photo} {title} - {description} {/photo} {/photos}
Sea walnuts have a colorless, walnut-shaped body. Two of the body lobes are longer than the rest. (Steven G. Johnson/Wikimedia Commons)

Comb jellies are transparent, jelly-like invertebrates with bright, iridescent color bands. They live near the water’s surface in the middle and lower Chesapeake Bay.

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

  • Sea walnut, Mnemiopsis leidyi
  • Pink comb jelly, Beroe ovata

Appearance:

  • Transparent, jelly-like bodies
  • Bright, iridescent color bands, which are made up of tiny hairs called combs. The bands divide the body into eight symmetrical parts.
  • Sea walnuts have a colorless, walnut-shaped body. Two of the body lobes are longer than the rest.
  • Pink comb jellies have a sac- or egg-shaped body that is often tinted pinkish to reddish-brown
  • Grow to about 4 inches

Habitat:

  • Live near the surface of both shallow and deep waters
  • Swim by beating their combs rhythmically to push themselves forward
  • Sea walnuts often swim together in large swarms

Range:

  • Sea walnuts are the more widely distributed species. They occur as far north as the Baltimore area. They are present year-round but are most common in spring and summer.
  • Pink comb jellies can be found in late summer to autumn in the middle and lower Chesapeake Bay, south of Kent Island, Maryland

Feeding:

  • Voracious feeders of planktonic organisms, including copepods and fish larvae
  • Can consume almost 500 copepods per hour
  • Eat by continuously pumping water into their body cavities

Predators:

  • Even though they are both comb jellies, the pink comb jelly is a major predator of the sea walnut

Reproduction and Life Cycle:

  • Spawn at night when water temperatures warm to 66-73 degrees
  • Comb jellies have both male and female reproductive organs and can fertilize themselves. Each comb jelly releases about 8,000 eggs per spawn.
  • Unlike jellyfish, comb jellies develop without distinctive larval and polypoid stages
  • Comb jellies species are difficult to distinguish from each other when they are young
  • Young are able to reproduce 13 days after hatching

Other Facts:

  • Unlike jellyfish, comb jellies do not have stinging tentacles
  • Comb jellies break apart when taken out of the 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, sea walnut color bands glow soft green

  • Although sea nettles and other stinging jellyfish are more well-known, comb jellies are much more abundant in the Bay

Sources and Additional Information:


410 Severn Avenue / Suite 112
Annapolis, Maryland 21403
Tel: (800) YOUR-BAY / Fax: (410) 267-5777
Directions to the Bay Program Office
Terms of Use | Privacy Policy
©2012 Chesapeake Bay Program | All Rights Reserved