Southern Stoplight Loosejaw, Malacosteus australis Kenaley 2007
Other Names: Black Hinged-head, Black Loosejaw, Blunthead Dragonfish
Southern Stoplight Loosejaw, Malacosteus australis. Source: Australian National Fish Collection, CSIRO. License: CC by Attribution-NonCommercial-ShareAlike
Summary:
A species of barbeled dragonfish found in the deep waters off southern and south-eastern Australia.
Cite this page as:
Bray, D.J. 2022, Malacosteus australis in Fishes of Australia, accessed 04 Mar 2025, https://fishesofaustralia.net.au/Home/species/1807
Southern Stoplight Loosejaw, Malacosteus australis Kenaley 2007
More Info
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Distribution |
East of Moreton Island, Queensland, to ESE of Bremer Bay, Western Australia. Elsewhere the species occurs in temperate and sub-Antarctic waters of the southern hemisphere, the tropical Indian Ocean, and waters of the Indo-Australian Archipelago. |
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Features |
Dorsal fin 16-21; Anal fin 18-23; Pectoral fin 3-5; Pelvic fin 6; Branchiostegal rays 7-9; Vertebrae 45-51. Male postorbital photophore 3.7-6.4% upper jaw length, 0.9-1.7% SL; female postorbital photophore 2.5-4.4% upper jaw length, 0.6-1.2% SL; IP photophores 5-7 in 3-7 clusters. |
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Size |
Maximum known length is 16.6 cm for a male and 19.2 cm for a female. |
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Feeding |
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). |
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Biology |
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 the colour 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 bioluminescence. 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. |
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Remarks |
Loosejaws have a flexible connection between the occiput and the first vertebra, allowing them to swallow large prey items by bending their head far back to widen their gape. |
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Similar Species |
Differs mainly from Malacosteus niger in having a smaller postorbital photophore in both sexes, lower numbers of lateral photophores, somewhat smaller jaws and a fleshy orbit. |
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Etymology |
The specific name australis is from the Latin austral, meaning "southern" in reference to the southern distribution of this species. |
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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. |
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Author |
Bray, D.J. 2022 |
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Resources |
Southern Stoplight Loosejaw, Malacosteus australis Kenaley 2007
References
Gomon, M.F., Glover, C.J.M. & Kuiter, R.H. (eds). 1994. The fishes of Australia's south coast. State Print, Adelaide. 992 pp. (as Malacosteus sp.)
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. https://doi.org/10.1643/0045-8511(2007)7[886:ROTSLG]2.0.CO;2
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.
Schnell, N.K. & Johnson, G.D. 2017. Evolution of a functional head joint in deep-sea fishes (Stomiidae). PLoS ONE 12(2): e0170224: 1-11. https://doi.org/10.1371/journal.pone.0170224
Williams, A. 2020. Malacosteus australis. The IUCN Red List of Threatened Species 2020: e.T137568083A137570724. https://dx.doi.org/10.2305/IUCN.UK.2020-1.RLTS.T137568083A137570724.en. Accessed on 20 October 2022.
