ongoing

Octopus tetricus, or Gloomy octopus, as it is locally known, is an adorable sea creature that owes this pet name to the big, white, sad-looking eyes, and to the common belief that they were loners. Even so, there is evidence that they do hold social interactions amongst their kin. Their eight arms (octo meaning eight in Greek) are typically grey to mottled brown (similar to seaweed) and show distinctive orange-rust colour that taper to the tip. However, they have the ability to change colour camouflaging and blending with the environment. Their arms are moderate to long (3 to 4.5 times the mantle length) and larger octopus have 220 to 260 suckers on each normal arm. They weight 1 kg and have a length of 6o cm, with a mantle length extending to 14 cm.

Across Bondi, Tamarama and Bronte, Gloomy octopus dwell on intertidal rocky shores and in the ocean during the breeding season, but otherwise, they enjoy spending their time in soft-sediment habitats. During the day, they sit in their lairds to avoid predators. At night, they emerge to feed on crabs and molluscs using their sharp beak. From scallops, a favourite for them, once eaten, they use their shells to dig and stabilise their burrows. Gloomy octopus is territorial and sits in its lair during the day surrounded by rocks and rubble that has been collected to defend its home. They use their arms to creep about rocks but can also display jet propulsion for fast movement or to throw shells when fighting with each other. When facing danger to a predator, they would discharge toxic ink that temporarily blinds the predator, giving Gloomy time to escape.

Females produce numerous (about 15,000) small eggs (1-2mm) that will be attached in strings to the roof of rock crevices, where the mother will remain vigilant until they hatch into planktonic young. They have a relatively short lifespan of about 11 months, depending on the environment. Predators can be moray eels, other reef predators and humans.

Images courtesy Niki Hubbard.