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Jellyfish

Sea nettles are a type of jellyfish common in the Chesapeake Bay. (Wally Gobetz/Flickr)
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Sea nettles are a type of jellyfish common in the Chesapeake Bay. (Wally Gobetz/Flickr)

Jellyfish are floating animals with gelatinous, umbrella-shaped bells and stinging tentacles.

Three species of jellyfish can be found in the Chesapeake Bay:

  • Sea nettle, Chrysaora quinquecirrha
  • Moon jellyfish or common jellyfish, Aurelia aurita
  • Lion’s mane jellyfish, Cyanea capillata

Appearance:

  • Transparent, gelatinous body
  • Umbrella-shaped bell called a medusa
  • Tentacles with stinging cells hang from the bell. The stinging cells are called nematocysts.
  • Sea nettles have a smooth, milky white bell that grows to about 4 inches in diameter. Up to 24 tentacles hang from under the bell.

  • The moon jellyfish is the Bay’s largest jellyfish. It can grow 10-12 inches in diameter. Hundreds of short tentacles hang like fringe from the bell’s edge.

  • The lion’s mane jellyfish has a broad, flattened bell and eight clusters of short tentacles. The bell is usually orange-brown and grows to about the same size as the sea nettle.

Habitat:

  • Found throughout brackish and salty waters, including shallow waters, open waters and tidal rivers

Range:

  • Sea nettles are abundant in May-October as far north as the Chesapeake Bay Bridge
  • Moon jellyfish visit the lower Chesapeake Bay in summer
  • Lion’s mane jellyfish are common in the Bay in late November-March

Feeding:

  • Sea nettles and lion’s mane jellyfish prey upon fish, shrimp, comb jellies and other small creatures
  • Use their stinging tentacles to entangle, paralyze and capture their prey. Each stinging cell is like a barb that injects venom into its prey. Jellyfish then use their tentacles to move the food into their mouth, which is located under the center of the bell.
  • Moon jellyfish eat plankton, including mollusks, crustaceans and copepods

Predators:

  • Many larger species, including fish, crustaceans and sea turtles, eat sea nettles

Reproduction and Life Cycle:

  • Sea nettles spawn in mid-summer. They die after spawning.
  • Males release sperm into the water. Females’ eggs are fertilized as they swim and pump water through their body.
  • After fertilization, eggs develop into tiny, free-swimming larvae called planulae, which the female releases into the water
  • Larvae float with the currents for a few days, then settle and attach to a firm surface. The larvae blossom into anemone-like polyps that bud and grow over the winter.
  • By spring, the polyps develop tiny, floating medusae that are layered on top of one another. The medusae are eventually released into the water.
  • The freely floating medusae (called ephyra) eventually grow tentacles and mature into adults

Other Facts:

  • Jellyfish are macrozooplankton, the largest of the Bay’s planktonic animals
  • Jellyfish propel themselves through the water by rhythmically expanding and contracting their bells. However, they are not very good swimmers; jellyfish are mostly transported by wind and currents.
  • Sea nettles are nearly 90 percent water
  • Wear a wet suit or pantyhose when swimming to avoid receiving a painful jellyfish sting

Sources and Additional Information:




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