Spotting the way octopus stripes vary could help us conserve them

A distinct striped pattern on a species of octopus varies from one individual to the next, which could help researchers monitor the rare animal.

Pygmy zebra octopuses (Octopus chierchiae), also known as lesser Pacific striped octopuses, live in shallow waters on the Pacific coast of the Americas and have alternating brown and white stripes running across them.

Little is known about the animal or how it interacts with its environment, so a team at the University of California, Berkeley, led by Benjamin Liu and Leo Song bred two adult males with two adult females in a laboratory.

The team individually housed 25 octopus hatchlings, then photographed and filmed them once a week for around two years.

When the octopuses were about two weeks old, their patterns became visible to the naked eye and were fully visible by four weeks. Pygmy zebra octopuses frequently change their appearance to mimic their surroundings in response to a disturbance, so the researchers only focused on the patterns that persisted for hours or days.

They found that each of the 25 octopuses had a unique configuration of stripes.

Volunteers who were shown photographs of the octopuses could even identify whether the images were of the same animal or two different ones, with an average accuracy of 84.2 per cent.

This suggests that individual pygmy zebra octopuses could be repeatedly identified and monitored in the wild over time, potentially aiding their conservation, the researchers write in their paper. These octopuses are rare and delicate, so should ideally be studied in a way that doesn’t remove them from their natural environment, they write.

While the stripes on pygmy zebra octopuses appear to vary between individuals, why they have these stripes at all is unclear. “The fact that they can turn the stripes on and off and even do it unilaterally suggests to me that they are used in communication or at least to make signals more obvious,” says Roy Caldwell, who was an author of the study.