Cannonball Jellyfish
Stomolophus meleagris

Contributors: DuBose B. Griffin and Thomas M. Murphy (SCDNR)

DESCRIPTION

Taxonomy and Basic Description
Cannonball, or cabbagehead, jellyfish(Stomolophus meleagris; L. Agassiz 1860), also known as jellyballs, belong to the class Scyphozoa and order Rhizostomeae. Agassiz (1860) described and illustrated the medusa of cannonballs using specimens collected from Wassaw Island, Georgia and Charleston, South Carolina. The hemisperical bell reaches 20 to 25 cm (8 to 10 inches) in size and is bordered with brown pigment. It has short, protruding oral arms with secondary mouth folds (scapulets) at the base of the bell covered with mucus for trapping small prey. Stomolophus meleagris means “many mouthed hunter.” The mucus is also thought to be a response to disturbance rather than for feeding (Phillips et al. 1969; Larson 1976).

Status
The cannonball jellyfish is not a state or federally listed species; however, cannonballs
are ecologically important because they are the major prey base for the endangered
leatherback sea turtle (Dermochelys coriacea) and warrant conservation.
POPULATION DISTRIBUTION AND SIZE
Cannonball jellyfish have been reported from New England to Brazil in the western
Atlantic (Kramp 1961; Larson 1976), from southern California to Ecuador in the eastern
Pacific and from the Sea of Japan to the South China Sea in the western Pacific (Kramp
1961; Omori 1978). They are one of the most abundant scyphomedusae along the
southeastern and Gulf coasts of the United States (Mayer 1910; Kraeuter and Setzler
1975; Burke 1976; Calder and Hester 1978). Their success is based in part on their ability
to grow rapidly and take advantage of ephemeral secondary production (Larson 1986).
Current distributions of most populations are undocumented. However, numerous reports
of their occurrence in the southeast exist. Mayer (1910) reported them as abundant
during the winter and spring off the coast from Florida to South Carolina. Brooks (1882)
and Gutsell (1928) reported them in North Carolina as very abundant in June and July
and common throughout the summer in the sounds and ocean. In South Carolina and
Cannonball jellyfish
SCDNR
Georgia, they are reported as the most common scyphomedusae occurring sporadically
year round (Kraeuter and Setzler 1975; Calder and Hester 1978).
The seasonal cycle of cannonball jellyfish is described by Rountree (1983) as the
following:
“Small populations of large adults appear offshore in the spring and move inshore
by early summer. The origin of these populations of adults has not been
determined, but it seems likely that they are survivors from the previous season
(Kraeuter and Setzler 1975). It is also possible that they are early spawned medusae
from more southern waters which are carried north by prevailing spring ocean
currents…Kraeuter and Setzler (1975) found the young medusae move out from
estuarine waters into more saline waters as they grow. Two concurrent events are
therefore hypothesized: 1) first generation populations move from offshore in the
spring to inshore waters in the summer and finally into brackish waters in the fall;
2) second generation populations move out from estuarine waters beginning in the
mid-summer and continuing through the fall.”
The South Carolina Department of Natural Resources (SCDNR) has been conducting
surveys in the South Atlantic Bight since 1986 through a program called the Southeast
Area Monitoring and Assessment Program ??? South Atlantic Shallow Water Trawl Survey
(SEAMAP-SA). Tows were conducted each year in spring (April to May), summer (July
to August) and fall (October to November) in shallow coastal waters from Cape Hatteras,
North Carolina to Cape Canaveral, Florida. From 1989 to 2000, only the presence or
absence of cannonball jellyfish was recorded on each individual tow. During this time,
cannonballs were present in 43 percent of the tows during all three survey seasons.
Beginning in 2001, total numbers of cannonballs were counted and recorded for each tow
(102 tows per season; J. Boylan and P. Webster, SCDNR, pers. comm.). These data are
presented in the following bar graph. Since 2001, there has been an apparent steady
decline in the relative abundance of cannonballs with very low catch rates observed in
2004. The reason(s) for this decline are unknown; however, anomalously low summer
water temperatures in the coastal waters in summer 2003 may be related.
Tow counts of cannonball jellyfish from 2001 ??? 2004.
Year
2001 2002 2003 2004
Total Number of Individuals
0
20000
40000
60000
80000
Mean Weight of Individual (kg)
0.0
0.2
0.4
0.6
0.8
1.0
Total for Year
Spring
Summer
Fall
Mean Weight
In another study, density and distribution of leatherback sea turtles were associated with
abundance and distribution of cannonball jellyfish. Mean numbers of leatherbacks
observed for each sampling event in each year was related to the density of cannonball
jellyfish observed from 2001 through 2003. However in 2004, cannonballs were in
unprecedented low numbers and leatherbacks were still observed. These data are
presented in the graph below. Numbers of cannonballs observed from 2001 though 2003
provided a relative index for leatherback abundance (S.R. Murphy unpub. data).
HABITAT AND NATURAL COMMUNITY REQUIREMENTS
Cannonball jellyfish are found in estuarine and saline waters. Temperature and salinity
measured during the SCDNR SEAMAP-SA tows (unpub. data) indicate they are found in
waters with an average temperature of 23.1°C (74°F) and in salinities from 17.7 to 36.5
parts per thousand (ppt) with an average of 33.8 ppt. Cannonballs feed on zooplankton,
primarily bivalve veligers, a mollusk larval stage (Larson 1991). They have also been
shown to prey on all stages of red drum larvae (Duffy et al. 1997). However, they do not
sting humans (Calder and Prodgen 1977). Cannonballs are strong horizontal and
directional swimmers (Shanks and Graham 1987). They are known for their symbiotic
relationships with other marine species, specifically 10 species of fishes as well as
juvenile longnosed spider crabs (Libinia dubia). These symbionts feed on both the
zooplankton taken in by the jellyfish and on the host’s medusae. Symbionts may also use
the bell for protection (Corrington 1927; Gutsell 1928; Phillips et al. 1969; Rountree
1983).
Annual shifts in abundance of leatherback and cannonball
jellyfish observations, 2001 ??? 2004.
198
339
132
2
124
690
120
347
0
100
200
300
400
500
600
700
800
2001 2002 2003 2004
Year
Number
Mean number of cannonball jellyfish per tow
Mean number of leatherbacks per flight x 10
THREATS
Since cannonball jellyfish are dependent on the abundance of zooplankton in nearshore
waters, any activity, marine or terrestrial, that could affect water quality, should be
considered a threat to this species. Such threats include harmful algal blooms, oil spills
and nonpoint source pollution. Also, their dependence on bivalve veligers suggests a
relationship with the health of bivalves.
The potential for cannonball jellyfish to be adversely affected by commercial fishing is
also a threat. Currently, South Carolina does not regulate a commercial cannonball
jellyfish fishery. However, this fishery does exist in other portions of the cannonball’s
range. Japan imports 5,400 to 10,000 tons of jellyfish products valued at 25.5 million
dollars annually (Omori and Nakano 2001). Currently, Asian countries are developing
fisheries management plans to conserve jellyfish because populations are unstable or
declining due to pollution, overfishing or climate change. Consequently, dealers are
looking for new sources of jellyfish (Hsieh et al. 2001). Interest in cannonball jellyfish
from the United States increased recently because of high consumer demand in Asia
(Hsieh et al. 2001). A fishery in Florida has processed cannonball jellyfish since 1992
(Rudloe, 1992) and a commercial trawl fishery for cannonball jellyfish in Georgia exists
(M. Dodd, GADNR pers. comm.). Rising demand in Japan and Southeast Asia may
create an international market for cannonball jellyfish from South Carolina coastal
waters. Any development of commercial fisheries for cannonballs must consider its affect
on this species’ role in the food web of coastal ecosystems, as well as the affects on
endangered leatherback sea turtle through incidental mortality in trawls and reduction of
their food resources. Life cycles of cannonball jellyfish involve federal and state waters;
therefore, cannonballs should be managed on a regional scale (S.R. Murphy unpub. data).
CONSERVATION ACCOMPLISHMENTS
In 1989, SCDNR began surveying cannonball jellyfish during SEAMAP-SA tows. These
surveys have provided an index of relative abundance of cannonball jellyfish in coastal
waters along the southeastern United States, which has led to a better understanding of
this species. In addition, current regulations requiring the use of turtle excluder devices
(TEDs) in shrimp trawling nets has also provided protection to cannonball jellyfish.
Although required to reduce incidental catch of turtles, TEDs also excludes cannonballs
greater than 10 cm (4 inches), thus increasing survival. TEDs have been required for
shrimp trawls since 1990.
CONSERVATION RECOMMENDATIONS
??? Determine the distribution of cannonball jellyfish in state waters and how this
species affects the distribution of leatherback sea turtles.
??? Examine basic life history and determine source of the spring recruitment of
cannonball jellyfish.
??? Determine effect of temperature, salinity and rainfall on spring reproduction.
??? Determine southeastern population structure through genetic analysis of
cannonballs.
??? Continue to monitor population trends through SCDNR SEAMAP-SA sampling
of cannonballs.
??? Determine the maximum sustainable yield for a harvest fishery.
??? More fully examine the species role in predator-prey dynamics.
??? Encourage municipalities to adopt Best Management Practices (BMPs) that
protect water quality and bivalve health by reducing nonpoint source runoff from
highways, agricultural fields and housing developments.
??? Monitor effectiveness of existing BMPs such as setbacks, retention ponds, and
vegetated buffers for preventing nutrient and contaminant runoff into coastal
waters.
??? Examine relationship between bivalve populations and cannonball reproduction.
??? If a fishery develops in South Carolina for cannonball jellyfish, it should be
monitored and regulated to avoid overexploitation and appropriate harvest
techniques should be identified that are protective of other marine species.
??? Facilitate the development of a regional management plan for cannonballs.
??? Develop an education program that stresses that cannonball jellyfish are important
and active members of the coastal ecosystem and are harmless to humans.
MEASUREMENTS OF SUCCESS
Determining the distribution, life history, habitat needs and southeastern population
structure and trends would represent a measure of success for this species. Methods that
protect water quality are also likely to protect cannonball jellyfish and associated
predator/prey relationships. In the event that more protective BMPs are implemented,
SEAMAP data can be used to indicate whether these measures have affected cannonball
jellyfish populations. Producing a regional management plan for this species would
greatly benefit the cannonball jellyfish throughout the southeastern coastal area.
LITERATURE CITED
Agassiz, L. 1860. Contributions to the natural history of the United States of America.
Vol 3. Little Brown and Co., Boston. 301 pp.
Brooks, W.K. 1882. List of medusae found at Beaufort, N.C., during the summers of
1880 and 1881. Stud. Biol. Lab. Johns Hopkins Univ. 2:135-146.
Burke, W.D. 1976. Biology and distribution of the macrocoelenterates of Mississippi
Sound and adjacent waters. Gulf Resource Report 5:17-28.
Calder, D.R. and B.S. Hester. 1978. Phylum Cnidaria. In: An annotated checklist of the
biota of the coastal zone of South Carolina. R.G. Zingmark (ed). University of
South Carolina Press:87-93.
Calder, D.R. and Prodgen. 1977. Guide to common jellyfishes of South Carolina. South
Carolina Sea Grant Marine Advisory Bulletin 11.
Corrington, J.D. 1927. Commensal association of a spider crab and a medusa. Biology
Bulletin. 53:346-350.
Duffy, J.T., C.E. Epifanio and L.A. 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 212:123-131.
Gutsell, J.S. 1928. The spider crab, Libinia dubia, and the jellyfish, Stomolophus
meleagris, found associated at Beaufort, North Carolina. Ecology 9(3):358-359.
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Georgia estuaries. Bulletin of Marine Science 25(1):66-74.
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-------------- 1986. Feeding and growth of the sea nettle Chrysaora quinquecirrha (DeSor)
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of jellyfishes in Mississippi Sound with quantitative data on the associative
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and its symbionts, with special emphasis on behavior. Undergraduate Thesis-
UNCW. 69p.
Rudloe, J. 1992. Jellyfish: a new fishery for the Florida panhandle. A report to the U.S.
Department of Commerce Economic Development Administration. EDA Project
no. 04-06-03801, pp. 35.
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meleagris L. Agassiz (Scyphozoan: Rhizostomida). Journal of Experimental
Biology and Ecology 108:159-169.