Summary

Idiosepius notoides is a coleoid cephalopod related to the cuttlefish and the bobtailed squids. It is commonly known as the Southern Pygmy Squid because it is found in Australian waters from southern Queensland along the coast to Tasmania and southern Western Australia (Norman and Reid 2000) and typically grows to a maximum mantle length (ML) of only 16mm to 20mm (Tracey et al. 2003). This species is typically yellow to brown in colour (Norman and Reid 2000), but like all cephalopods, it has the ability to rapidly change the colour and pattern of its skin using specialised organs known as chromatophores. The body of I. notoides is elongated with a rounded posterior mantle to which a pair of fins that aid in locomotion is attached. An adhesive organ found on the dorsal surface of the mantle is unique to Idiosepius spp. and is used to attach the animal to vegetation (Mangold et al. 2013). The habitat of I. notoides is typically seagrass beds (Zostera and Heterozostera spp.) (Norman and Reid 2000) but it has also been found attached to macro algae (seaweed) (Tracey et al. 2003). 

As a cephalopod, I. notoides shares fascinating characteristics with other members of this group, which includes the cuttlefish, squid and octopus. The camouflage capabilities of these animals are well known, as is their ability to release ‘ink’ to aid in escape from predators. Cephalopods also have highly developed sensory systems and a complex central nervous system which rival those of vertebrates (Ruppert et al. 2004).

I. notoides attached to Caulerpa sp. Photograph by Samantha Reynolds.