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.

A Southern Ocean Sunfish on the surface

B. & J. Carter © B. & J. Carter

Standard Common Name

Southern Ocean Sunfish

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 Sunfish

Distribution

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.

The map below shows the Australian distribution of the species based on public sightings and specimens in Australian Museums. Click on the map for detailed information.  Source: Atlas of Living Australia.

Mola ramsayi

Distribution by collection data

Ozcam map of Southern Ocean Sunfish specimens in the Australian Museum.

What does this mean?

Classification

Species:
ramsayi
Genus:
Mola
Family:
Molidae
Order:
Tetraodontiformes
Class:
Actinopterygii
Subphylum:
Vertebrata
Phylum:
Chordata
Kingdom:
Animalia

What does this mean?

References

  1. 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.
  2. Hutchins, B. & R. Swainston. 1986. Sea Fishes of Southern Australia. Complete Field Guide for Anglers and Divers. Swainston Publishing. Pp. 180.
  3. Hutchins, B. & M. Thompson. 1983. The Marine and Estuarine Fishes of South-western Australia. Western Australian Museum. Pp. 103.
  4. Thys, T.M. et al. 2013. First record of the southern ocean sunfish, Mola ramsayi, in the Galapagos Marine Reserve. Marine Biodiversity Records. DOI:10.1017/S175526723000377. Vol 6.
  5. Last, P.R., E.O.G. Scott & F.H. Talbot. 1983. Fishes of Tasmania. Tasmanian Fisheries Development Authority. Pp. 563.


Mark McGrouther , Collection Manager, Ichthyology
Last Updated:

Tags fishes, ichthyology, Southern Ocean Sunfish, Mola ramsayi, Molidae, brown, grey, odd-shaped, round, > 2 m, countershaded, pelagic, marine, adult, long fin rays,

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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