ANIMAL SPECIES:Southern Ocean Sunfish, Mola ramsayi (Giglioli, 1883)
The Southern Ocean Sunfish is a huge round-bodied fish that is sometimes seen 'basking' on the water surface in southern Australian waters.
Identification
The Southern Ocean Sunfish is a deep bodied species with high dorsal and anal fins placed posteriorly on the body. It has a small mouth with teeth fused into a parrot-like beak. The skin is leathery with rough denticles. Large fish have a ridge above and behind the eyes.
This fish is brown to grey above often with pale blotches, and paler below. After death it becomes white.
Four species of sunfish are found in Australian waters, the Southern Ocean Sunfish, Ocean Sunfish, Mola mola, Slender Sunfish, Ranzania laevis, and the Point-tailed Sunfish, Masturus lanceolatus. The two species of Mola can be separated by the number of ossicles in the clavus (the tail frill). M.ramsayi has 12 ossicles that are wider than the spaces between them. M.mola has 8 to 9 ossicles that are narrower than the spaces between them. There is a distinct band of smaller denticles at the base of the clavus in M.mola that is lacking in M.ramsayi.
Size range
The species grows to 3.3 m in length.Similar Species
Ocean Sunfish, Sharptail SunfishDistribution
It occurs in oceanic waters of the South Pacific Ocean.
In Australia it is found in temperate marine waters from northern New South Wales, around the south of the country, including Tasmania, to south-western Western Australia.
Distribution by collection data
Biomaps map of Southern Ocean Sunfish specimens in the Australian Museum collection.
Classification
- Species:
- ramsayi
- Genus:
- Mola
- Family:
- Molidae
- Order:
- Tetraodontiformes
- Class:
- Actinopterygii
References
- Glover, C.J.M. in Gomon, M.F., Glover, C.J.M. & R.H. Kuiter (Eds). 1994. The Fishes of Australia's South Coast. State Print, Adelaide. Pp. 992.
- Hutchins, B. & R. Swainston. 1986. Sea Fishes of Southern Australia. Complete Field Guide for Anglers and Divers. Swainston Publishing. Pp. 180.
- Hutchins, B. & M. Thompson. 1983. The Marine and Estuarine Fishes of South-western Australia. Western Australian Museum. Pp. 103.
- Last, P.R., E.O.G. Scott & F.H. Talbot. 1983. Fishes of Tasmania. Tasmanian Fisheries Development Authority. Pp. 563.
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A Southern Ocean Sunfish on the surface View full size
B. & J. Carter
© B. & J. Carter
Southern Ocean Sunfish, Mola ramsayi View full size
NSW fisheries, Schoalhaven office
© NSW fisheries, Schoalhaven office
Head of a Southern Ocean Sunfish View full size
NSW fisheries, Schoalhaven office
© NSW fisheries, Schoalhaven office
Clavus of a Southern ocean Sunfish View full size
NSW fisheries, Schoalhaven office
© NSW fisheries, Schoalhaven office
Holotype of Orthagoriscus ramsayi View full size
J. Catherall
© The Natural History Museum
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4 comments
Mark McGrouther
2.07 PM, 01 July 2009
Hi Joshua, You are quite right. The teeth of the sunfishes, and indeed a number of other families in the order Tetraodontiformes, are fused into a beak. Other examples are the spiny pufferfishes or porcupinefishes (family Diodontidae) in which there is a single fused 'plate' in both jaws and the pufferfishes (family Tetraodontidae), which have two 'plates' in both jaws. Yes, I agree that the sunfishes certainly don't have the 'typical' streamlined fishy shape.
peppercorn
11.07 AM, 01 July 2009
Mark i would also like to bring foward in pointing out that there teeth arent morphed into array of rows but instead are like a beak of a bird.Also unlike your usual fish they dont have a sleek knife like body.
Mark McGrouther
8.07 AM, 01 July 2009
Good point Sascha! I should have explained that better. Your description is spot on. The ossicles on the clavus of adult sunfishes look a bit like fingernails or, if you use a little imagination, the toenails of an elephant. I have add a link from the page to the new glossary. Thanks again for your comment.
Sascha Schulz
4.06 PM, 30 June 2009
Would I be correct in assuming the ossicles are the half-moon shaped structures visible in the photo of the clavus?
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