Luminous Bay Squid
Reported from all of eastern Australia from tropical north Queensland to temperate Tasmania. This wide range may represent more than one species (QLD, NSW, VIC, TAS).Features:
A small squat cylindrical squid that reaches around 13 cm long. There are two large rounded fins that run along half of the body length and join at the rear tip. Overall, the fins form a heart shape. They have eight arms and two retractable feeding tentacles. The arms and tips of the feeding tentacles have suckers each with a horny, toothed rim. Shell as a transparent feather-shaped structure. Colour pattern of black, brown and orange large dots (chromatophores) over a transparent background. The skin is smooth.Ecology/Way of Life:
This small squid occurs in shallow coastal habitats to depths of around 50 m, particularly around seagrass beds. This species is very tolerant of low salinities allowing it to forage in estuaries and brackish water. It is most active at night hunting for crustaceans and fish. It maintains buoyancy through constant swimming, using a combination of the fins and jets of water through the funnel.
The common and scientific names of this squid come from its light-producing abilities (bioluminescence). The squid has a special symbiotic relationship with glowing bacteria. Within its gill cavity it has two special light organs that contain living bacteria. The bacteria are fed sugars by the squid in return for producing light. The squid then uses this light to hide its silhouette when it is swimming around at night. It lets out just enough light to match the background moonlight or starlight, effectively hiding it from fish predators waiting below.
Little is known of reproduction in this species. The adult male has a special modified lower left arm where the suckers have been replaced by rows of fingers of skin. This arm may help pass sperm packages to the female or may be used to remove the sperm of previous males.
This squid is short-lived (at least in northern Australia), living only 70 days.Interaction with Humans/Threats:
This squid is caught incidentally in inshore trawls, at least in north-east Australia. It can be confused with the juveniles of the larger more commercial squid species.Further Reading:
Lu, C.C., Roper, C.F.E. and R.W. Tait. 1985. A revision of Loliolus (Cephalopoda: Loliginidae) including L. noctiluca, a new species of squid from Australian waters. Proceedings of the Royal Society of Victoria, 97: 59-85.
Norman, M.D. and A. Reid. 2000. A guide to the squid, cuttlefishes and octopuses of Australasia. Gould League/CSIRO Publishing, Melbourne. 96 pp.
Norman, M.D. 2000. Cephalopods: A world guide. ConchBooks, Hackenheim, Germany.
Text, map & photograph by Mark Norman, Museum Victoria.Sponsorship welcomed:
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