Shore Crabs

I've been a fan of shore crabs all the way back to childhood summer holidays on Vancouver Island. They're so different from most land creatures - 10 legs, big claws, eyes on stalks. I remember when I was maybe 8 or 10 years old taking the train from Saskatoon to Vancouver and then arriving at Tsawwassen for the ferry to Vancouver Island. The first thing I had to do was rush down to the shore and start turning over rocks to find crabs.

Happily, there are shore crabs under the rocks in front of our place in Victoria. I've been meaning to bring some inside (temporarily) to "study" them and I finally got around to it. I filled a small container with gravel and water from the beach and grabbed an assortment of crabs. The small ones, roughly pea sized immediately burrowed into the gravel and I didn't see them again. But the three slightly larger ones (~ 2 cm or 3/4 in) were a bit more visible. At first they hid under shells, but they seemed to get accustomed to the environment and roamed around more. They weren't as happy being taken out and put in a white bowl to be photographed.

The largest one got braver as time went by. It would roam the edges of the container, looking for a way out. It occurred to me that it was a good thing it wasn't any bigger or it would be able to escape. I left the container uncovered and went and got some tea. As I was returning I saw something on the floor. It took me several seconds to figure out it was a crab. Luckily I was able to grab it before it hid somewhere I couldn't reach. I was more careful after that and kept the lid on except when I was actually watching them. And yet it managed one more escape when I glanced away for a few seconds. I made a grab for it but it jumped straight off the edge of my desk. I returned it once more and after that managed to avoid any more escapes. It reminded me of when I kept garter snakes as a kid. One of them managed to escape and I swear my father levitated when it came across the living room carpet towards him. Coming from 10 years in East Africa where the snakes tended to be considerably more dangerous might have had something to do with it.

Shore crabs are amphibious, able to survive both in the water and in the air. This one was hiding under a rock underwater.

Here's the escape artist, waiting patiently for an opportunity. I didn't actually see him climb out, but I saw some attempts where he'd stand on a rock and stretch out sidewise. He must have managed to hook one leg over the edge and do a one arm/leg pullup.

Another unique feature of crabs is their eyes. They are compound eyes like an insect, but on "stalks" that allow them to swivel and retract. Their eyes don't have very good resolution, but they can spot an approaching bird or other predator.

This one was slightly smaller, but easily recognized. I called him Spot.

I also picked up some unintentional critters. We tend to think of limpets as fixed in place, but this little one roamed around all the time (eating algae off the rocks presumably). It was tiny, maybe 1/2 cm (1/4 in). I think it's a Mask Limpet.

I fed them a couple of times on tiny pieces of salmon that I stole from Shelley's lunch. They obviously have a good sense of smell in the water. Soon after dropping in the food, they would all emerge and start hunting around for it. Once they grabbed a piece they'd scuttle back to shelter to eat it. After a couple of days I returned them to the beach.

There are a multitude of crabs here. The otters eat them, humans eat them, even the gulls eat them if they can catch them. This morning I kayaked across a shallow muddy bay at low tide and there were hundreds of roughly 5cm (2 in) crabs, one every foot or so.

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