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 resides in 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 prefers 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 eats 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]

Habitat

I. pygmaeus is heavily concentrated in seagrass meadows. They are known to attach to seagrass using a special organ that supports adhesion. However, human activities have disturbed seagrass meadows. This habitat used for shelter by organisms such as Idiosepius is threatened.^[3][8]