PORT PHILLIP BAY


Short Sunfish 

Mola ramsayi (Giglioli, 1883)

View scientific description and taxonomy

Scientific Details

Meristics.
Dorsal fin spines/rays: 15-18
Anal fin spines/rays: 15-18
Caudal fin rays: (clavus) 16
Pectoral fin rays: 11

Interpreting fin count meristics.
Spines are in Roman numerals and soft rays are in Arabic numerals. Spines and rays that are continuous in one fin are separated by a comma. Fin sections are separated by semicolons.

Detailed descriptions of fin count and other meristics are in:
Gomon. M.F., Bray, D.J. & Kuiter, R.H. (eds) (2008) Fishes of Australia's Southern Coast. Sydney : Reed New Holland 928 pp.

Order level detail.
The Tetraodontiformes is a very diverse and specialized group of bony fishes that share the loss, reduction or fusion of many bony structures in the head and body. Fins and their supporting elements are reduced or lost, and vertebrae are reduced in number. They have small mouths with modified teeth that may be enlarged or fused into a beak-like structure, or incorporated into the jaw bones. The gill opening is reduced to a small slit near the pectoral-fin base, and most have thick skin, covered in scales that are modified into spines, ossicles or fused bony plates. Some groups are poisonous, and the puffers and porcupinefishes are highly inflatable. Puffers adn their allies are found worldwide in temperate and tropical seas, and a few species enter freshwaters.

Family level detail.
Ocean sunfishes of the family Molidae are the largest bony fishes in the world. These breathtaking oceanic giants have a unique body shape, with deep compressed bodies, high dorsal and anal fins at the rear and a truncated tail region. Instead of a caudal fin, molids have a clavus (meaning rudder in Latin) - a deep, stiff lobe at the end of the body formed from extensions of the dorsal and anal fin rays. Widespread in tropical and temperate waters, usually in the open ocean far offshore. Most inshore records are based on specimens washed ashore.

Taxonomy

Phylum:
Chordata
Subphylum:
Craniata
Superclass:
Gnathostomata
Class:
Actinopterygii
Order:
Tetraodontiformes
Family:
Molidae
Genus:
Mola
Species:
ramsayi

General Description

Body very deep, slightly oblong to nearly circular in lateral profile, with thick leathery skin covered in rough denticles, caudal fin absent, replaced by a clavus; clavus with a scalloped margin supported by about 16 rays, with 12 rays bearing closely spaced ossicles, ossicles much broader than spaces between; skin at clavus base uniform, band of reduced denticles absent. Dull brown or greyish above, becoming whitish below. To 3.3 m.

Biology

This species is more common in southern Australia than Mola mola. Its biology is poorly known.

Habitat

Oceanic waters, occasionally entering coastal bays.

Open water

Distribution guide

Southern Hemisphere, including Australian waters.

Species Group

Fishes Sunfishes

Depth

Shallow (1-30 m)

Water Column

Midwater Surface

Max Size

3.3 m

Commercial Species

No

Global Dispersal

Recorded in Australia

Conservation Status

  • DSE Advisory List : Not listed
  • EPBC Act 1999 : Not listed
  • IUCN Red List : Not listed

Author

article author Bray, D.J.

Di Bray is a Senior Collection Manager of ichthyology at Museum Victoria.

Author

article author Gomon, M.F.

Dr. Martin Gomon is a Senior Curator of ichthyology at Museum Victoria.

citation

Cite this page as:
Bray, D.J. & Gomon, M.F., 2011, Short Sunfish, Mola ramsayi, in Taxonomic Toolkit for marine life of Port Phillip Bay, Museum Victoria, accessed 30 Jun 2017, http://portphillipmarinelife.net.au:8098/species/6521

Text: creative commons cc by licence