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.
Known Predators:
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”.
Range mass: 143 to 1378 g.
Average length: 12.7 cm.
Other Physical Features: ectothermic ; heterothermic ; radial symmetry ; venomous
Sexual Dimorphism: sexes alike
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.
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 ; saltwater or marine
Aquatic Biomes: coastal
Other Habitat Features: estuarine
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 ; tactile
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.
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
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
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 )
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 ; source of medicine or drug
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.
Commensal/Parasitic Species:
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.
Animal Foods: fish; eggs; zooplankton
Primary Diet: carnivore (Piscivore , Eats eggs, Eats non-insect arthropods); planktivore
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 (Native ); pacific ocean (Native )
The medusae stage is the sexually reproducing and motile stage of the jellyfish. Gametes are released into the water.
Mating System: 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 ; asexual ; fertilization (External ); broadcast (group) spawning
Fertilization occurs outside Stomolophus meleagris, and no parental care occurs.
Parental Investment: no parental involvement
'Stomolophus is usually described as the most abundant scyphozoan in the Gulf, particularly in the late summer and fall when it 'swarms' around inlet passes.' (Rountree 1983)
'The scyphozoan Stomolophus meleagris , when disturbed (held in a container), discharges a sticky mucus. Toxins released into the mucus and water kill some fish and crustaceans and can immediately alter fish behavior, but did not affect a crab predator of S. meleagris . The mucus contains discharged and undischarged nematocysts. The toxins in the mucus are probably associated with these nematocysts.' (Oldendorf 1988)
'After swimming actively for 2-5 days, the ciliated planula larvae settled and scyphistoma morphogenesis occurred. Fully developed scyphistomae were cone-shaped and bore a whorl of about 16 tentacles around a dome- or knob-shaped proboscis. Podocyst formation was the only observed method of asexual reproduction in cultures of scyphistomae maintained for one month. Strobilation began as soon as nine days after scyphistoma morphogenesis and occurred in scyphistomae with as few as eight tentacles... Most strobilae produced two ephyrae each, although the number varied from one to three. Some scyphistomae began to strobilate a second time within a week after completion of an initial round of strobilation.' (Calder 1982)
Dome-shaped bell can be up to 25 cm (10 inches) in diameter.
Feed on zooplankton and red drum larvae.
'A pilot plant process was developed to produce salted dried jellyfish product from cannonball jellyfish (Stomolophus meleagris). Processed products containing an average of 68% moisture, 5.5% protein, 26% ash and 25% salt were obtained by brining with different mixtures of salt (7.5–25%) and alum (1–2.5%) over 1 wk. Mechanical drying was also tested by using a heat pump system dryer. Chemical and physical analyses and sensory properties of cannonball jellyfish products compared favorably with market products. Levels of calcium, magnesium and iron in the jellyfish were higher than those of zinc and copper.' (Huang 2006)
The cannonball jellyfish (Stomolophus meleagris), also known as the cabbagehead jellyfish, is a species of jellyfish in the family Stomolophidae. Its common name derives from its similarity to a cannonball in shape and size. Its dome-shaped bell can reach 25 cm (10 in) in diameter and, in the Atlantic and Gulf of Mexico, the rim is often colored with brown pigment. There are two known undescribed Stomolophus species found in the Pacific that exhibit pale to blue pigment. They are genetically different from the individuals found in the Atlantic - but are commonly misidentified as such. Underneath the body is a cluster of oral arms that extend out around the mouth. These arms function in propulsion and as an aid in catching prey.[2] Cannonballs are prominent from North America's eastern seaboard all the way to Brazil.
They are common on the southeastern coast of the United States, including the Gulf Coast. On the southeast coast they are extremely abundant in the fall and summer months. During these months, cannonballs make up over 16% of the biomass in the shallow inshore areas.[3]
Cannonballs eat mainly zooplankton such as veligers, and also all forms of red drum larvae. They have a symbiotic relationship with the portly spider crab, which also eats the small zooplankton. The crab feeds on the prey captured by the cannonball and also on the medusae of the jellyfish.[4]
As in most cnidarians sexual reproduction is not an imperative way for cannonballs to reproduce. They can reproduce both sexually and asexually.[5]
During sexual reproduction, cannonballs shoot sperm out of their mouth. The sperm are then caught by another cannonball through the mouth and fertilization happens. The embryo begins to develop in specialized pouches found on the arms around the mouth. After about 3–5 hours the larvae fall to the bottom and attach themselves to a hard structure. There they develop into polyps and catch small prey that swims by. After several days the polyp will detach and become a swimming ephyra, and will eventually turn into an adult jellyfish.[6]
When disrupted, the cannonball secretes a mucus out of its nematocyst that contains a toxin. The toxin harms small fish in the immediate area, and drives away most predators, except for certain types of crabs.[7] Although cannonballs do not commonly sting humans, they do have toxins which can, but not usually, cause cardiac problems in animals and humans. The toxin can cause irregular heart rhythms and problems in the myocardial conduction pathways. Such complications are associated also with toxins of other cnidaria.[8] The toxin is also harmful to the eyes; contact with a nematocyst can be very painful, followed by redness and swelling. However, cannonball jellyfish are mostly harmless to humans. Contact with them may cause the skin to itch slightly, or minor eye irritation. As such they are among the most common causes of minor stings to humans in US and Caribbean waters.[9]
One of the main predators of cannonball jellyfish is the endangered species leatherback sea turtle.[10] Cannonball jellyfish are also commercially harvested as food for humans.[11]
Along the coast of the southern U.S. state of Georgia, jellyfish are a valuable export, which end up on dining tables across Asia. The jellyfish are dried, preserved and packaged before being sold to a seafood distributor that ships them to Japan, China, and Thailand.
Jellyball (as they are known locally) fishing is Georgia’s third largest commercial fishery.[12] In Georgia, fishermen target jellyfish with modified trawl nets, and studies have shown low quantities of bycatch are typically seen in the fishery.[13]
Recently, Mexican coasts have experienced an increase in the abundance and frequency in blooms of this jellyfish. In 2012 El Golfo de Santa Clara harvested 20,000 tons (~$3.5 million USD) from late April to early July, which elevated the importance of this resource in the region. However, further studies need to be done in order to increase the predictability and improve the management strategies.[14]
This article incorporates public domain text from the Voice of America, at http://www.voanews.com/english/news/usa/US-Jellyfish-Land-on-Asian-Dinner-Tables-143681576.html
The cannonball jellyfish (Stomolophus meleagris), also known as the cabbagehead jellyfish, is a species of jellyfish in the family Stomolophidae. Its common name derives from its similarity to a cannonball in shape and size. Its dome-shaped bell can reach 25 cm (10 in) in diameter and, in the Atlantic and Gulf of Mexico, the rim is often colored with brown pigment. There are two known undescribed Stomolophus species found in the Pacific that exhibit pale to blue pigment. They are genetically different from the individuals found in the Atlantic - but are commonly misidentified as such. Underneath the body is a cluster of oral arms that extend out around the mouth. These arms function in propulsion and as an aid in catching prey. Cannonballs are prominent from North America's eastern seaboard all the way to Brazil.
