|Case in point; "Smiley". 2009 photo.|
Trouble is, shore crabs do very well for themselves in an aquarium; steady temperatures, clean water, ample diet, and no predators, to boot! So they grow up large and strong.
And the bigger a crab gets, the more disruptive he becomes. He digs himself a deep burrow, throwing aside carefully-placed landscaping and piling leftovers on top of his neighbours' land. He then goes out to steal food from whoever has any, and retreats to his hole to eat it all in peace. No sharing! When his hole gets untidy, as it does - he's a messy eater - he abandons it and digs himself a new shelter. Again, he tosses his construction trash next door.
In between, he goes a-hunting. Freshly-molted young hermit is tasty; so is a snail that he can crack between his pincers. He can snatch a speeding amphipod out of the water without a miss. And a nice mouthful of green sea lettuce makes a good garnish. Leftovers are tossed into the current.
But even the non-edible, glued-in-place residents come in for their share of harassment. Enter the burrowing anemone.
|"Val", from Campbell River. Nicely healed, growing a sturdy, button-studded column.|
Hermit crabs crawl all over the anemones, picking up bits of debris, grooming the tentacles. Sometimes the anemone shuts down for a bit; more often it doesn't. They're friends. Big Patch, the crab, tried to imitate them, but was not welcomed, probably with good reason. I watched on several occasions as the crab approached. When he came within reach of a tentacle, he leaped backwards, as if shocked. He tried over and over, always with the same result. The anemone's stinging cells are good protection.
Revenge is sweet, says Patch.
He dug a hole right next door, and buried the anemone with broken shells and gravel. Val shut down; can't feed under all that heavy construction debris. I raked through the stuff with my fingers, removed the gravel, left clean sand around the base of Val's column.
Patch dug another, deeper hole. Val shut down. I cleaned up. Patch pushed a load of sand halfway across the aquarium and piled it on top. I cleaned up.
|Burrowing anemone, White Rock beach.|
(On the beaches, most of these anemones cling to rocks, sheltered from tidal sand pile-ups. I accidentally dug up the one above that I found in sand instead, by trying to measure its column depth with a finger. It had nothing to hold it, and rolled out of the sand. A wave caught it and hauled it away, probably food for whatever fish got to it first.
The anemones on the beach in Campbell River, where Val originated, usually anchor themselves in sandstone pits, sheltered by seaweeds. There is very little loose sand for the crabs to move about.)
|Cluster of anemones in sandstone, Storries Beach, Campbell River.|
Val has anchored hirself to the glass bottom of the aquarium, for safety, but that means only a certain depth of stuff will be tolerated around the column. Patch kept burying hir.
Eventually, I moved Patch's favourite clam and oyster shells to the far end, re-arranged all the landscaping, plants, rocks and all, so as to leave nothing nearby to be piled on top of Val. Overnight, Patch hauled it all back, and re-buried his enemy.
|Patch, showing off his Alpha male, XL pincers. Val in the background, shut down. What's the sense of fighting back?|
So: it's time. Patch is too big for his britches, too big for a tank he must share. He's been exiled to a quarantine tank, with a couple of other growing crabs. Next trip to the beach, they're going along. They'll do fine there; they're large and healthy, if a bit spoiled.
Val is sitting in an empty plane, in lonely splendour, waving tentacles happily in the current.