The striped pyjama squid is one of the few known poisonous cephalopods (squid, octopus, cuttlefish, and nautilus) that roam the seafloor of the Indo-Pacific Oceans, along with the flamboyant cuttlefish and the southern blue-ringed octopus. Scientists believe that the striped pyjama squid's distinctive black stripes give away its venomous nature to potential predators, but small glands under the body are responsible for releasing the toxic slime that is dangerous to passersby.
Despite its common name, the striped pyjama squid is actually a species of cuttlefish, a versatile animal that can often change its appearance, has an internal shell, eight arms and two feeding tentacles. The striped pyjama squid's small and rounded appearance like that of a dumpling has inspired other people to commonly refer to it as the striped dumpling squid. It lives in sand and mud habitats of shallow coastal waters from southern Great Barrier Reef to central South Australia.
Similar to other small cephalopod species, the striped pyjama squid is a master of disguise and during daylight will bury itself in a background of sand and broken shells so that only the top of its head is visible. Its yellow eye is usually the only part of the cuttlefish that pokes above the sea floor. At night, the cuttlefish emerges to feed on small shrimp and fish. Two long fins flank the sides of the striped pyjama squid's body and the arms of its two feeding tentacles have small suckers, each with a toothed horny rim. The underside of its body is covered in small glands that secrete slime when the striped pyjama squid is under attack, quickly scaring off any predators from making a move. It can also drastically change color to a dark purple-brown, making it easier to camouflage itself against rocks and corals near the bottom of the ocean.
The male pyjama squid begins mating by grabbing a female and positioning itself so that they are head-to-head. He then places his sperm packet close to her mouth where she stores it to use when she lays her eggs. If the male finds sperm from a previous male, he will attempt to remove it with a specialized scoop on his lower arm. Females lay round white eggs in little clumps on the seafloor or under coral rubble, and young hatchlings are born with their black pyjama stripes already fully visible. Striped pyjama squid will only reach about 7 centimeters in length when fully grown.
Data are lacking on the conservation status of striped pyjama squids. They are not typically targeted by commercial fishing, but their shallow coastal habitat is susceptible to human impact. More research is needed to fully understand the status of the striped pyjama squid and their future in our oceans.