Behind the image
When Justin suited up to photograph a kelp experiment off Tasmania, he came away with more than just seaweed.
Octopus and crabs
The Maori octopus was desperately attempting to blend in with the onslaught of prey animals and hunt them at the same time.
It was a crisp, clear December day, and Justin was preparing for what he anticipated would be a relatively straightforward assignment – photographing a series of miniature kelp forests in a shallow stretch of water known as the Mercury Passage, near Tasmania’s Maria Island. The seaweed, which had been painstakingly transplanted onto concrete blocks in patches of varying size and density, was part of a study on thinning – a consequence of habitat degradation that is impacting kelp ecosystems across Australia’s cool seas.
As he snapped away, Justin’s attention was diverted by the sudden appearance of a colony of giant spider crabs, which proceeded to stampede through the research area in a mob the size of a football field. During the autumn-winter moult, these crustaceans are known to gather in vast numbers in Port Phillip Bay, Melbourne, hunkering out of sight beneath wooden jetties while their new shells harden, before returning to deeper water. However, the species had never been documented around Maria Island before.
The arrival of the crabs was as much a surprise for Justin as it was for a Maori octopus that was quietly patrolling the sand – an impressive cephalopod that boasts a tentacle-span of 2m, and that mercilessly ambushes prey along the seabed. “The octopus was clearly excited and started rapidly changing colour, desperately attempting to blend in with the onslaught of prey animals and hunt them at the same time,” recalls Justin. “The unexpected appearance of the crabs reinforces just how little we still know about Australia’s temperate reef ecosystem, an important, highly productive habitat that we need to acknowledge as much as we do our coral reefs.”
JUSTIN GILLIGAN Hailing from Australia, Justin is a photojournalist and marine scientist. See more of his work at justingilligan.com