Idiosepius pygmaeus

Idiosepius pygmaeus, also known as the two-toned pygmy squid or tropical pygmy squid, is a species of bobtail squid native to the Indo-Pacific. It occurs in the waters of the South China Sea, Japan, Philippines, Palau, Indonesia, the Northern Mariana Islands, as well as northern and northeastern Australia. The squid traditionally inhabits shallow, inshore waters.^[3][4]

Idiosepius pygmaeus
Adult
Hatchlings (c. 2 mm long) stained with phosphotungstic acid (left) and Lugol's iodine (right)
Conservation status
Data Deficient  (IUCN 3.1)[1]
Scientific classification
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Cephalopoda
Order:	Idiosepida
Family:	Idiosepiidae
Genus:	Idiosepius
Species:	I. pygmaeus
Binomial name
Idiosepius pygmaeus Steenstrup, 1881[2]

I. pygmaeus weighs 0.00033 g upon hatching and increases in weight to 0.175 g as it reaches maturity in 50 days (1260 degree days). The squid resides in waters at a temperature of 25.2 °C. Growth rate has been calculated as 12.55 and physiological growth rate as 0.498.^[5]

I. pygmaeus grows to a mantle length of 20 mm.^[3]

This species has been reared on a diet of glass shrimp (Acetes sibogae australis) in the laboratory.^[6]

The type specimen was collected in the South China Sea (04°20′N 107°20′E) and is deposited at the Zoologisk Museum of Kobenhavns Universitet in Copenhagen.^[7]

Idiosepius pygmaeus is heavily concentrated in seagrass meadows. They are known to attach to seagrass using a special organ that supports adhesion. However, due to environmental changes caused by human activities, seagrass meadows have been disturbed. This habitat used for shelter by organisms such as Idiosepius is being threatened.