''Uroteuthis noctiluca'', commonly known as the luminous bay squid, is a species of squid native to shallow water on the eastern coast of Australia. It uses a pair of luminous organs to camouflage itself from

predators Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill th ...

at night.

Description

In this species, females grow larger than males. The maximum mantle length is about , the width of the mantle being about 30% of the length. The fins are rounded and the posterior of the mantle is heart-shaped. The eight arms are short and there are rings of suckers on each arm, each sucker having four to seven teeth. The male has the fourth left arm hectocotylised over its entire length. The two tentacles are short and robust, with broad paddle-shaped clubs. There are two

photophore A photophore is a glandular organ that appears as luminous spots on various marine animals, including fish and cephalopods. The organ can be simple, or as complex as the human eye; equipped with lenses, shutters, color filters and reflectors, ...

s on the underside of the

ink sac An ink sac is an anatomical feature that is found in many cephalopod mollusks used to produce the defensive cephalopod ink. With the exception of nocturnal and very deep water cephalopods, all Coleoidea (squid, octopus and cuttlefish) which dwell ...

. Populations in the north of the range differ from those in the south in the arrangement of the suckers on the male's right ventral arms. This squid has a colourless cuticle with a pattern of orange, black and brown dots.

Distribution and habitat

''Uroteuthis noctiluca'' is found in shallow waters on the eastern coast of Australia, its range extending from southern

Queensland ) , nickname = Sunshine State , image_map = Queensland in Australia.svg , map_caption = Location of Queensland in Australia , subdivision_type = Country , subdivision_name = Australia , established_title = Before federation , establishe ...

Tasmania ) , nickname = , image_map = Tasmania in Australia.svg , map_caption = Location of Tasmania in AustraliaCoordinates: , subdivision_type = Country , subdi ...

. It is often in

seagrass meadow A seagrass meadow or seagrass bed is an underwater ecosystem formed by seagrasses. Seagrasses are marine (saltwater) plants found in shallow coastal waters and in the brackish waters of estuaries. Seagrasses are flowering plants with stems and ...

s at a maximum depth of about .

Biology

This small squid is short-lived, surviving for about seventy days in tropical waters but rather longer than this in the temperate south of its range. It is tolerant of low salinity and is often found in brackish water, bays and estuaries. It is active at night, foraging for

crustacean Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean group can ...

s and small fish. The photophores on its underside can be partially revealed to provide

camouflage Camouflage is the use of any combination of materials, coloration, or illumination for concealment, either by making animals or objects hard to see, or by disguising them as something else. Examples include the leopard's spotted coat, the b ...

at night by concealing the squid's

silhouette A silhouette ( , ) is the image of a person, animal, object or scene represented as a solid shape of a single colour, usually black, with its edges matching the outline of the subject. The interior of a silhouette is featureless, and the silhou ...

from below, the light output being varied to match the moonlight or starlight. The light organs of squid contain luminescent bacteria in the family

Vibrionaceae The Vibrionaceae are a family of Pseudomonadota given their own order, Vibrionales. Inhabitants of fresh or salt water, several species are pathogenic, including the type species ''Vibrio cholerae'', which is the agent responsible for cholera. ...

; a number of different species of bacteria are involved, and some squid species host multiple strains. Little is known of the reproductive behaviour of this squid. The male's specially adapted hectocotylis arm is likely to be used to deposit a

spermatophore A spermatophore or sperm ampulla is a capsule or mass containing spermatozoa created by males of various animal species, especially salamanders and arthropods, and transferred in entirety to the female's ovipore during reproduction. Spermatophores ...

in the female's mantle, or to clear out sperm from a previous mating.

References

{{Taxonbar, from=Q1998746 Squid Molluscs described in 1985