3rd Place Compact Behavior

PT Hirschfield

"Spider Crab Conga Line"

The Story: I’ve been photographing the annual spider crab aggregations in Victoria, Australia for over a decade. I was astonished and thought I was dreaming during a solo dive at a pier while visiting South Australia when I stumbled across an aggregation of around 400 spider crabs. Despite running a spider crab social media group, I had never heard of spider crabs at this particular location, or at this time of year. Usually the spider crabs aggregate in the shallows to moult their old shells. But these crabs were all fully moulted with hardened shells. More surprising still was seeing so many crabs lined up in the same direction, as though forming a conga line, with others looking to join the line, all looking directly into my camera. There were a few mating pairs scattered around the pier, so I suspect that this aggregation and conga line behaviour might be part of a mating aggregation which I haven’t seen anywhere in the literature, as opposed to the well-documented moulting aggregations. No-one I’ve spoken with has observed this conga line behaviour before - is it part of the missing link of what is known about spider crab reproductive behaviours?  I was gutted after I posted about my discovery of this aggregation online, only for a video I took to be circulated amongst people who started planning how to target these near-inedible animals for food or sport, prompting me to delete the video. It’s important that marine life not be targeted at critical times in their life cycles. It was a reminder that image making can be a double-edged sword. I hope that my images will contribute to greater respect for the species, and greater measures of protection for them when they are most vulnerable. 

Location: Fleurieu Penninsula, South Australia

Equipment Used: Canon G12, Single YSD3 strobe, Fix Neo 1500 Light

Camera Settings: ISO 125, F6, 1/125 sec

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