I had a few seconds only; hermits don't stay in vulnerable positions for long.
|Two hairy hermits (Pagurus hirsutiusculus), mating. The smaller, green legs belong to the female; the male is bigger, and has red algae growing on his hairs.|
It's springtime, and love is in the air. And the water. But it's difficult for hermit crabs; to mate, they have to crawl at least partway out of their shells, exposing their soft, juicy abdomens. And crabs are always on the lookout for fresh meat. A researcher timed his hermits; copulation lasted from 10 to 36 seconds, repeated up to 4 times.
I managed to get half a dozen blurry, bubbly photos. No time to wipe down the glass first, nor to turn off the pump.
|View from the top. Bubbles and swimming copepods deleted, contrast increased. The female is the one on the right; her abdomen is visible, almost entirely out of the shell.|
Either she had just molted (crabs have to wait until the female molts, because of the hard carapace she's wearing normally), or she molted soon afterwards; I found her molted bits and pieces up against the glass in the morning.
I paused to wipe off the glass quickly. When I looked again, a few seconds later, both hermits were back in their shells and walking away, in different directions.
If the mating was successful, the female will be visibly in berry soon; the baby hermits will hatch in about 3 weeks. They'll be too small to see, except as moving specks in a filter, against a bright light.
I have watched the preliminary courting behaviour many times. (I reported on it here: "A friend for Boy Blue", and "Little Bo-Peep is fast asleep.") I had never managed to catch them actually in the act.
Made my day. Theirs, too, I think.