Cannonball jelly (Stomolophus meleagris)
N omb res comu n es: Medusa bala de cañón (Español)
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Taxon biology
Stomolophus meleagris, otherwise known as the cannonball jellyfish, is a species of jellyfish that
resembles a cannonball in both shape and size. It has oral arms underneath its body that extend out
around the mouth. This species feeds mainly on zooplankton and has a symbiotic relationship with the
portly spider crab, which also feeds on zooplankton. Like most cnidarians, the cannonball jellyfish can
reproduce both sexually and asexually.
Distribution 1,2
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.
Bi ogeograp h i c R egi on s: atlantic ocean (Native ); pacific ocean (Native )
Morphology 1,2
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”.
R an ge mass: 143 to 1378 g.
Average l en gth : 12.7 cm.
Oth er Ph ysi cal Featu res: ectothermic ; heterothermic ; radial symmetry ; venomous
Sexu al Di morp h i sm: sexes alike
Size 3
Dome-shaped bell can be up to 25 cm (10 inches) in diameter.
Habitat
Depth range based on 13 specimens in 1 taxon.
Water temperature and chemistry ranges based on 9 samples.
Environmental ranges
Depth range (m): 0 - 128
Temperature range (°C): 18.920 - 26.658
Nitrate (umol/L): 0.325 - 6.247
Salinity (PPS): 35.209 - 36.499
Oxygen (ml/l): 3.418 - 4.870
Phosphate (umol/l): 0.085 - 0.636
Silicate (umol/l): 0.756 - 4.097
Graphical representation
Depth range (m): 0 - 128
Temperature range (°C): 18.920 - 26.658
Nitrate (umol/L): 0.325 - 6.247
Salinity (PPS): 35.209 - 36.499
Oxygen (ml/l): 3.418 - 4.870
Phosphate (umol/l): 0.085 - 0.636
Silicate (umol/l): 0.756 - 4.097
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.
Trophic strategy 1,2
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.
An i mal Food s: fish; eggs; zooplankton
Pri mary Di et: carnivore (Piscivore , Eats eggs, Eats non-insect arthropods); planktivore
Associations 1,2
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.
Commen sal /Parasi ti c Sp eci es:
Long nosed spider crabs, Libinia dubia
Harvestfish, Peprilus paru
Bumpers, Chloroscombrus chrysurus
Ecology 3
'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)
Behaviour 1,2
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.
Percep ti on Ch an n el s: visual ; tactile
Life cycle 1,2
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 nonmotile 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.
Devel op men t - Li fe Cycl e: metamorphosis
Life expectancy 1,2
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.
Reproduction 1,2
The medusae stage is the sexually reproducing and motile stage of the jellyfish. Gametes are released
into the water.
M ati n g 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.
K ey R ep rod u cti ve Featu res: sexual ; asexual ; fertilization (External ); broadcast (group) spawning
Fertilization occurs outside Stomolophus meleagris, and no parental care occurs.
Paren tal In vestmen t: no parental involvement
Conservation status 1,2
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 Fed eral Li st: no special status
CITES: no special status
State of M i ch i gan Li st: no special status
Uses 1,2
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.
N egati ve Imp acts: injures humans (bites or stings, venomous )
References
1. Afford, H. and T. Patel 2013. "Stomolophus meleagris" (On-line), Animal Diversity Web. Accessed
April 27, 2013 at
http://animaldiversity.ummz.umich.edu/site/accounts/information/Stomolophus_meleagris.html
2. © The Regents of the University of Michigan and its licensors, some rights reserved
3. © Wolf, Elizabeth, some rights reserved