Jellyfish
Order: Semaeostomeae
A lion's mane jellyfish visits Spa Creek in Annapolis, Md., on March 31, 2009. (Photo by Alicia Pimental/Chesapeake Bay Program)
A sea nettle drifts in Spa Creek at Annapolis Marina in Annapolis, Md., on Aug. 9, 2010. (Photo by Matt Rath/Chesapeake Bay Program)
A lion's mane jellyfish drifts through Spa Creek in Annapolis, Md., on Jan. 18, 2017. The lion's mane jellyfish is sometimes called the "winter jellyfish" and visits the Chesapeake Bay from late November through March. (Photo by Will Parson/Chesapeake Bay Program)
A sea nettle floats in the Severn River Sanctuary in Anne Arundel County, Md., on July 10, 2016. (Photo by Will Parson/Chesapeake Bay Program)
A school of Atlantic silverside swims past a sea nettle at Dogwood Harbor in Tilghman Island, Md., on Sept. 1, 2015. Sea nettles grow to about 4 inches in diameter and use their stinging tentacles to entangle, paralyze and capture fish, shrimp, and other small animals. (Photo by Will Parson/Chesapeake Bay Program)
Sea nettle in turbid water. (Photo by Steve Droter/Chesapeake Bay Program)
The lion’s mane jellyfish has a broad, flattened bell and eight clusters of short tentacles. (Elanna/Flickr)
Hundreds of short tentacles hang like fringe from the edge of the moon jellyfish's bell. (Jim G/Flickr)
The lion's mane jellyfish's bell is usually orange-brown. It grows to about the same size as the sea nettle. (Eric Heupel/Flickr)
The moon jellyfish is the Chesapeake Bay’s largest jellyfish. It can grow 10-12 inches in diameter. (Takashi Hososhima/Flickr)
Jellyfish are floating animals with gelatinous, umbrella-shaped bells and stinging tentacles.
Appearance
Three species of jellyfish can be found in the Chesapeake Bay: sea nettles, Chrysaora quinquecirrha, moon jellyfish or common jellyfish, Aurelia aurita, and lion’s mane jellyfish, Cyanea capillata.
Jellyfish have a transparent, gelatinous body and an 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 to 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.
Feeding
Sea nettles and lion’s mane jellyfish prey upon fish, shrimp, comb jellies and other small creatures. They 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.
Did You Know?
- 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
- Life in the Chesapeake Bay by Alice Jane Lippson and Robert L. Lippson
- Chesapeake Bay: Nature of the Estuary, A Field Guide by Christopher P. White
- Forecasting Sea Nettles – NOAA Chesapeake Bay Office
- Jellyfish of the Chesapeake – Maryland Sea Grant
- Animal Diversity Web: Aurelia aurita and Cyanea capillata – University of Michigan Museum of Zoology
- Common Jellyfish – ARKive
Quick Facts
Species
Native
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Size
Sea nettles and lion's mane jellyfish: 4 inch diameter; moon jellyfish: 10 to 12 inch diameter
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Habitat
Found throughout brackish and salty waters, including shallow waters, open waters and tidal rivers.
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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.
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Diet
Sea nettles and lion’s mane jellyfish feed on fish, shrimp and comb jellies; moon jellyfish eat plankton
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Status
Stable