Southern Loosejaw, Malacosteus australis Kenaley 2007

Other Names: Black Hinged-head, Black Loosejaw, Blunthead Dragonfish

Southern Stoplight Loosejaw, Malacosteus australis. Source: Rudie H. Kuiter / Aquatic Photographics. License: All rights reserved

A species of barbeled dragonfish found in the deep waters off southern and south-eastern Australia.

Cite this page as:
Bray, D.J. 2017, Malacosteus australis in Fishes of Australia, accessed 12 Jul 2020,

Southern Loosejaw, Malacosteus australis Kenaley 2007

More Info


Dorsal fin 16-21; Anal fin 18-23; Pectoral fin 3-5; Pelvic fin 6; Branchiostegal rays 7-9; Vertebrae 45-51.


Maximum known length is 16.6 cm for a male and 19.2 cm for a female.


Feeds on mesopelagic fishes and invertebrates, especially copepods. The Southern Loosejaw presumably uses the large accessory orbital photophore (AO) in employing a far-red visual system as part of its foraging strategy (Kenaley 2007).


Red light cannot penetrate into the deep oceanic waters, and as a result, most animals living in the deep-sea have lost the ability to see red. Therefore, the vast majority of bioluminescent animals living in the deep-sea produce a blue light. Not only does Malacosteus have a photophore just behind the eye that produces a blue light, they also have a large elliptical photophore under the eye that produces red bioluminscence. This allows them to shine a red light that cannot be seen by their unsuspecting prey, giving them a huge advantage in their dark environment.

Similar Species

Differs mainly from Malacosteus niger in having a a smaller postorbital photophore in both sexes, lower numbers of lateral photophores, somewhat smaller jaws and a fleshy orbit.


The specific name australis is from the Latin austral, meaning "southern" in reference to the southern distribution of this species.

Species Citation

Malacosteus australis Kenaley 2007, Copeia 2007(4): 893, Figs. 4-5. Type locality: Tasman Sea, off Brush Island, 35°36'S, 150°55'E, depth 650-2000 m.


Bray, D.J. 2017


Australian Faunal Directory

Southern Loosejaw, Malacosteus australis Kenaley 2007


Kenaley, C.P. 2007. Revision of the stoplight loosejaw genus Malacosteus (Teleostei: Stomiidae:, Malacosteinae), with description of a new species from the temperate Southern Hemisphere and Indian Ocean. Copeia 2007(4): 886-900.

Kenaley, C.P., Harold, A.S. & Gomon, M.F. 2008. Family Stomiidae. pp. 240-254 in Gomon. M.F., Bray, D.J. & Kuiter, R.H (eds). Fishes of Australia's Southern Coast. Sydney : Reed New Holland 928 pp.

Quick Facts

CAAB Code:37110001


Depth:500 to over 2000 m


Habitat:Mesopelagic, bathypelagic

Max Size:19+ cm SL

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CAAB distribution map