Stomolophus meleagris

Geographic Range

Stomolophus melegris , the cannonball jellyfish, is most abundant in the southeastern United States and the Gulf Coast. They also inhabit the western Atlantic from New England to Brazil, the eastern Pacific from southern California to Ecuador, and the western Pacific from the Sea of Japan to the South China Sea.

• Biogeographic Regions
• atlantic ocean atlantic ocean
  • native native
• pacific ocean pacific ocean
  • native native

Habitat

Stomolophus meleagris is found within saline and estuarine waters by the shoreline. The waters they inhabit are usually around 23.1 degrees C and on average the water salinity is 33.8 ppt.

• Habitat Regions
• tropical tropical
• saltwater or marine saltwater or marine

• Aquatic Biomes
• coastal coastal

• Other Habitat Features
• estuarine estuarine

Physical Description

Stomolophus meleagris is a small jellyfish, with a height of 12.7 cm and a width of 18.0 cm. Some have been found up to 25 cm in width. Mass ranged in one study from 143-1378 grams. The cannonball jellyfish looks like a thick hemispherical bell and can have several different color schemes, including milky blue or yellow, with or without a border of brown pigment. This jellyfish has 16 short, forked fused orals arms instead of the normal tentacles. Stomolophus meleagris also has secondary mouth folds (scapulets) covered with mucus, thought to be for trapping small prey. The name Stomolophus meleagris means “many mouthed hunter”.

• Other Physical Features
• ectothermic ectothermic
• heterothermic heterothermic
• radial symmetry radial symmetry
• venomous venomous

• Sexual Dimorphism
• sexes alike

Development

The life cycle of Stomolophus meleagris is very similar to the life cycle of many scyphozoans. Beginning as an elongated and cylindrical planula without a mouth, this species has an endodermal mass surrounded by a ciliated ectoderm. The planula swims around for a few days, then attaches to a substrate where it can metamorphosize into a scyphistoma (the sessile polyp stage).

The scyphistoma is flask-shaped and has a narrowing stalk. Tentacles begin to show near the bulbous calyx, and a mouth appears and is able to dilate. The oral disk contains the proboscis and 8 contractile tentacles appear as the scyphistoma develops. At the fully mature state, it has 16 filiform tentacles. The proboscis is developed along with the mouth. Scyphistomae eat and grow to a maximum size of a few millimeters. This stage can reproduce asexually, where the formation of podocysts and motile or non-motile buds can break off. These podocysts in the Scyphozoa are resistant to adverse environmental conditions.

The next stage, the strobila, occurs under favorable conditions, and involves segmentation and metamorphosis. Segmentation of incisions begins proximal to the tentacular ring, which would form segments representing ephyra (immature medusa). Thirty-six hours into the strobila process, the tentacles of S. meleagris start to regress, contract, and expand periodically. After 54 hours, all tentacles of the original scyphistoma are completely reabsorbed, but new tentacles began to regenerate. In the late strobila phase incisions deepen and separate the developing ephyrae, which increase in size and undergo rapid development. Ephyrae are liberated about 3.5 days after strobilation begins. Once the one or more free swimming ephyrae are released, the scyphistoma is small, but rapidly returns to normal size and can repeat strobilation.

From the ephyra the medusa, or sexual stage, forms and produces fertilized eggs that develop into the planula motile larva.

• Development - Life Cycle
• metamorphosis metamorphosis

Reproduction

The medusae stage is the sexually reproducing and motile stage of the jellyfish. Gametes are released into the water.

• Mating System
• polygynandrous (promiscuous) polygynandrous (promiscuous)

Stomolophus meleagris has a life history cycle like most other schyphozoans, with alternation of generations between asexually and sexually reproducing phases. The scyphistoma stage reproduces asexually.

The scyphistoma can enter a strobila stage that produces medusae, the sexually reproducing and motile stage of a jellyfish.

• Key Reproductive Features
• sexual sexual
• asexual asexual
• fertilization fertilization
  • external external
• broadcast (group) spawning

Fertilization occurs outside Stomolophus meleagris , and no parental care occurs.

• Parental Investment
• no parental involvement

Lifespan/Longevity

Stomolophus meleagris has an average lifespan from three to six months. Many of the jellyfish die within months because of predators, but throughout their short life they can reproduce many times.

Behavior

Stomolophus meleagris is a strong horizontal and directional swimmer as a mature adult. The jellyfish reacts strongly when disturbed, and uses stinging nematocysts for defense and to catch prey. When aggressively handled or approached by a boat, S. meleagris inverts so the oral arm mass is directed upward, perhaps even breaking the water surface, and then swim downward vigorously.

Like many other jellyfish, some stages of S. meleagris are sessile. Motile forms of this jellyfish can have swarms as large as 100 miles long.

• Key Behaviors
• natatorial natatorial
• sessile sessile
• motile motile
• colonial colonial

Communication and Perception

Social communication between jellyfish is not very common. Stomolophus meleagris , however, has been seen forming dense aggregations. Under certain conditions it also displays distinctive horizontal movements that may be related to waves, tides or other conditions.

The cannonball jellyfish has light sensing organs called rhopalia and statocysts to determine direction according to gravity. A nerve net is used to detect external stimuli like touch.

• Perception Channels
• visual visual
• tactile tactile

Food Habits

Stomolophus meleagris eats macrocrustaceans and zooplankton that are generally bivalve veligers, fish eggs and larvae. The will also feed on red drum larvae. They eat by sucking water into spaces within the sixteen scapulets (mouth folds) when the bell contracts.

• Primary Diet
• carnivore carnivore
  • piscivore piscivore
  • eats eggs
  • eats non-insect arthropods
• planktivore planktivore

• Animal Foods
• fish
• eggs
• zooplankton zooplankton

Predation

When Stomolophus meleagris is disturbed it secretes toxic mucus that can harm or drive away predators. One of the main predators of S. meleagris is the endangered leatherback turtle, Dermochelys coriacea . Other crabs and fish also eat this species.

Ecosystem Roles

Stomolophus meleagris affects the ecosystem in two main ways. These jellyfish are one of the main food sources of food for the endangered leatherback turtle, Dermochelys coriacea . Other species of fish and crustaceans use cannonball jellyfish as a source for food, including the stone crab Menippe mercenaria , blue crabs, Callinectes , and the Atlantic spadefish Chaetodipterus faber .

Cannonball jellyfish also form symbiotic relationships with marine species, including ten species of fish and the juvenile long-nosed spider crab, Libinia dubia . The symbionts use the jellyfish for protection and feed on the zooplankton that the jellyfish take in, as well as zooplankton that are on the medusa itself.

Most symbiotic relationships of S. meleagris are commensalistic, but some symbionts may be parasitic, feeding on the medusa itself. However, the medusa can generate quickly so the jellyfish is not harmed much.

Cannonball jellyfish numbers may also affect populations of their symbiotic fish and spider crabs. The symbionts could be depleted alongside the jellyfish, as some hide inside the bell cavity of the jellyfish when harvested. The symbionts can be injured in the process or simply lose the host from which they gather food.

Economic Importance for Humans: Positive

Stomolophus meleagris is harvested for food mainly in Asia. Demand for this species appears to be growing and the fishery has been expanding to include North American waters.

• Positive Impacts
• food food
• source of medicine or drug source of medicine or drug

Economic Importance for Humans: Negative

Although they have nematocysts, stinging cells, they are fairly innocuous to humans and do not cause much damage. Rarely, the sting can lead to cardiac problems.

• Negative Impacts
• injures humans
  • bites or stings
  • venomous venomous

Conservation Status

Stomolophus meleagris does not have a conservation status. However, it is a main food source for the leatherback turtle, Dermochelys coriacea , a critically endangered species under IUCN and a U.S.federally endangered species.

Additional Links

Encyclopedia of Life

Contributors

Heather Afford (author), Rutgers University, Tejal Patel (author), Rutgers University, David V. Howe (editor), Rutgers University, Renee Mulcrone (editor), Special Projects.

References

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Calder, D. 1982. Life history of the cannonball jellyfish, Stomolophus meleagris L. Agassiz, 1860 (Scyphozoa, Rhizostomida). Biol. Bull. , 162: 149-162. Accessed February 23, 2013 at http://www.biolbull.org/content/162/2/149.full.pdf .

Cebuly, T. 2011. "Cannonball jellyfish" (On-line). LHSVirtualZoo. Accessed February 23, 2013 at http://lhsvirtualzoo.wikispaces.com/Cannonball+Jellyfish .

Dickerson, N. 2011. "Cannonball Jellyfish ( Stomolophus melagris )" (On-line). Jellyfish Facts. Accessed February 23, 2013 at http://www.jellyfishfacts.net/news/cannonball-jellyfish-stomolophus-melagris-nid-71.html .

Duffy, J., C. Epifanio, L. Fuiman. 1997. Mortality rates imposed by three scyphozoans on red drum ( Sciaenops ocellatus Linnaeus) larvae in field enclosures. Journal of Experimental Marine Biology and Ecology , 212/1: 123-131.

Griffin B., D., T. Murphy M.. 2011. "Cannonball jellyfish: Stomolophus meleagris " (On-line). Accessed February 23, 2013 at http://www.dnr.sc.gov/cwcs/pdf/Cannonballjellyfish.pdf .

Hale, G. 1999. "The classification and distribution of the class Scyphozoa" (On-line). Accessed February 23, 2013 at http://gladstone.uoregon.edu/~ghale/pdf/scyphozoa.pdf .

Hsieh, P., J. Rudloe, F. Leong. 2001. Jellyfish as food. Hydrobiologia , 451: 11-17.

Larson J., R. 1991. Diet, prey selection and daily ration of Stomolophus meleagris , a filter-feeding scyphomedusa from the NE Gulf of Mexico. Estuarine, Coastal and Shelf Science , 32/5: 511-525.

Roundtree, R. 1983. The ecology of Stomolophus meleagris , the cannonball jellyfish, and its symbionts, with special emphasis on behavior . Wilmington, North Carolina: Honors program thesis, Department of biological sciences, University of North Carolina.