Complex Life Cycles

Did you know jellyfish are present in the Chesapeake Bay all year long?  Not always in the form we have all come to recognize as a possible stinging hazards. Jellyfish have one of the most amazing life cycles in the animal world - a visit to the Complex Life Cycles exhibit will shed light on these amazing creatures.

Despite reaching very large sizes in some species, jellyfish are considered plankton - at the mercy of the water's movements. The shape of the bay and being pushed where the wind and waves take them often leads to jellyfish occurring in dense swarms in the Chesapeake.

The term jellyfish is really a misnomer. These animals are not fish at all - they are invertebrates more closely related to corals and sea anemones. There are several varieties that occur in the Chesapeake - cnidarians like sea nettles, lion's mane and moon jellies (schyphozoans); cnidarians like Portuguese man 'o war (hyrdrozoans); and ctenophores like comb jellies. Each has unique characteristics and many have painful stingers.

Behind the scenes, jellyfish are raised from polyps to the free-swimming medusa seen in the exhibit. To sustain this process, we CULTURE OF LIFE FEED ORGANISMS - not unlike the “sea monkeys” you grew at home when you were younger.

Because of the delicate nature of jellyfish, only one species will be on exhibit at any time, though all are representative of Complex Life Cycles adaptations.

Sea Nettle

 Atlantic sea nettle

Scientific name: 
Chrysaora quinquecirrha

Distribution: Widely distributed species of jellyfish that inhabits tropical and subtropical parts of the Atlantic and Indo-Pacific. It is frequently seen along the East Coast of the United States, such as the Chesapeake Bay. 

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

Key characteristics for distinction: 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.

Coloration: Transparent, gelatinous body; typically pale, pinkish or yellowish, often with radiating more deeply colored stripes on the exumbrella,

Feeding habits/specializations: Sea nettles 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.

Reproduction: Spawns during morning, spermatozoa are released by the male, females collect the sperm and fertilize them with eggs and broods them within the folds. They will be released into the water as planulae. The free swimming larva stage is brief as it finds a place to settle down and then begins sessile stage of life as a polyp. It’s basically a mouth surrounded by tentacles. Through asexual budding, it produces clones of itself into a sort of colony. If all goes well, these polyps will develop into tiny, floating medusa that are layered on top of one another and are eventually released into the water as free floating medusa called ephyra. These ephyra will grow tentacles and mature into adults.

Maximum length (in inches or feet): 4 in diameter

Predators: Many larger species, including fish, crustaceans and sea turtles, eat sea nettles.

Conservation status: not evaluated

Fun fact: Sea nettles are nearly 90 percent water and have no brain.

Sources: fishbase.org, chesapeakebay.net, Wikipedia.org, aqua.org

Pink Comb Sea Walnut

Leidy's comb jelly

Scientific name: 
Mnemiopsis leidyi

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

Habitat: estuarine and marine habitats

Key characteristics for distinction: A lobed body that is oval-shaped and transparent, with four rows of ciliated combs that run along the body vertically and glow blue-green when disturbed. They have several feeding tentacles. Unlike cnidarians, Mnemiopsis doesn't sting. Their body contains 97% water.

Coloration: Translucent, gelatinous body; will glow blue-green if disturbed (bio-luminescence)

Feeding habits/specializations: consumes zooplankton including crustaceans, other comb jellies, and eggs and larvae of fish; it is sometimes known to eat smaller individuals of its own kind

Reproduction: This comb jelly has the capacity for self-fertilization, as they are hermaphroditic. They have gonads that contain the ovary and spermatophore bunches in their gastrodermis. This animal carries 150 eggs along each meridional canal. Eggs and sperm are released into the water column where external fertilization takes place. The spawning commences at late evening or at 1:00 or 2:00 a.m. The spawning eggs develop a thick outer layer within 1 minute after touching the seawater. As many as 10,000 eggs can be produced from large specimens in areas with good prey abundance.

Maximum length (in inches or feet): 5 in length / 1 in diameter

Predators: Many are vertebrates, including species of birds and fish. Some predators include other members of gelatinous zooplankton such as Beroe ctenophores and various Scyphozoa (jellyfish). Sea turtles (leatherbacks) also consume comb jellies.

Conservation status: not evaluated

Fun fact: The comb jelly it is a translucent walnut-shaped body with wart-like bumps, sometimes called a sea walnut.

Sources: aqua.org

Moon_Jelly

Moon jelly

Scientific name: 
Aurelia aurita

Distribution: The species Aurelia aurita is found along the eastern Atlantic coast of Northern Europe and the western Atlantic coast of North America in New England and Eastern Canada.

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

Key characteristics for distinction: 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. Can be recognized by its four horseshoe-shaped gonads, easily seen through the top of the bell

Coloration: Transparent, gelatinous body

Feeding habits/specializations: Moon jellyfish eat plankton, including mollusks, crustaceans and copepods

Reproduction: Spawns during morning, spermatozoa are released by the male, females collect the sperm and fertilize them with eggs and broods them within the folds. They will be released into the water as planulae. The free swimming larva stage is brief as it finds a place to settle down and then begins sessile stage of life as a polyp. It’s basically a mouth surrounded by tentacles. Through asexual budding, it produces clones of itself into a sort of colony. If all goes well, these polyps will develop into tiny, floating medusa that are layered on top of one another and are eventually released into the water as free floating medusa called ephyra. These ephyra will grow tentacles and mature into adults.

Maximum length (in inches or feet): 16 in diameter

Predators: Ocean Sunfish, Leatherback sea turtles, also sea birds but they may be more interested in the food collected in their bells than the actual moon jelly.

Conservation status: not evaluated for IUCN but stable condition

Fun fact: 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.

Sources: fishbase.org, chesapeakebay.net, Wikipedia.org, aqua.org