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Uroteuthis chinensis (Family Loliginidae)

Pencil Squid



Tropical western Pacific Ocean from Japan to the Gulf of Thailand and south to northern Australia (WA, NT, QLD, NSW).


Moderate to large elongate cylindrical squid reaching over 40 cm in length. Pair of large triangular fins on body, their length being over 60% of body length in adults. Fins join at rear tip, forming a diamond shape. There are eight arms and two extendable feeding tentacles. The arms and tips of the feeding tentacles have suckers with horny, toothed rims. The shell consists of a thin transparent feather-shaped structure. The gill cavity contains two round light organs, one on either side of the ink sac. Colour is generally orange to pink over transparent muscle. Skin is smooth.

Ecology/Way of Life:

This fast schooling squid occurs in coastal waters from the shore to depths of at least 170 metres. It is active at night. There are no observations of live behaviours. It maintains buoyancy through constant swimming, using a combination of the fins and jets of water through the funnel.

The main defense of this squid is its speed. It also uses its light-producing abilities (bioluminescence). It 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.

Spawning occurs throughout the year with peaks in spring and autumn. Animals gather in large numbers to lay eggs in strings on the seafloor. The adult male has two rows of skin fingers on the last third of the lower left arm instead of suckers. The function of these special structures is unknown.

Preferred Image

Interaction with Humans/Threats:

There may be more than one species of squid being treated under this scientific name. This squid (or group of squids) is very popular for human consumption and is targeted or taken in bycatch throughout its range in the tens of thousands of tonnes. It is harvested with a range of gear including bottom trawls, purse seines, cast nets, lift nets, dip nets, box nets, scoop nets, stake nets, baited lines and jig lines. Lights are often used to attract the squid.

Further Reading:

Dunning, M.C. 1998. Family Loliginidae. Pp. 764-780. In: Carpenter, K.E. and V.H. Niem (eds). The Living Marine resources of the Western Central Pacific. Volume 2: Cephalopods, crustaceans, holothurians and sharks. Food and Agriculture Organization of the United Nations, Rome. Pp. 688-1396.


Text, map & photograph by Mark Norman, Museum Victoria.

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Images and Multi-media:  
Attached Image  
image/jpeg 141001 bytes Pencil Squid
Distribution Map  
image/jpeg 42691 bytes Distribution of Pencil Squid
video/x-msvideo 869138 bytes Video of Urotheuthis sp.

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