Dive Dry with Dr. Bill

103: Nothing Sheepish About These Crabs

Yes, it's summer on the Island of Romance. Lots of mating going on underwater (and even topside for some) with the usual suspects participating- garibaldi, leopard sharks, Kellet whelks, surfperches and others. However, I didn't expect the encounter I had recently with two sheep crabs. After all, it's at the "tail" (or more appropriately, telson) end of their normal mating season.

On my first dive that day, my video light wouldn't function due to battery failure as I discovered topside. Since I had planned to film horn sharks sleeping in dark caves deep in the Casino breakwater, I had to abandon that attempt. On my second dive I went out on the sandy bottom (usually quite stirred up by dive classes, but this was midweek) so I could get more light for filming whatever might stumble in front of my camera.

It wasn't long before I saw a male sheep crab ambling along the bottom at a good pace. It took a few seconds to realize he was after a second sheep crab, a female, who was just entering thick kelp on the bottom to escape him. Hmmm? I knew these two were just perfect for one another (after all, they are of the same species and I always advocate mating within your own species... unless, of course, the ladies from planet Xanadu are really cute). Of course we humans have recourse to sites like, but these poor creatures could not link-up on-line. I decided to serve as a "match maker."

I picked up the female since it was much smaller and they have tiny claws compared to the males. I carried it over to the male and dropped her in front of him. It was love (er, lust?) at first sight. The male pounced on the poor girl and grabbed her with all his might, and his remaining legs since both his claws were missing ("eight legs to hold you?"). He held her tight as he manipulated her into a position that would permit successful mating.

I filmed them for several minutes before deciding that my SCUBA tank would last much longer at a shallower depth. I picked up the mating couple in one hand, carried my camera in the other, and slowly swam them up from 65 to 35 feet and placed them on the open sand where my filming would not be obscured. They continued mating and even tried a few new "positions" (none of which I could find in the Kama Sutra).

I sensed the presence of another organism near by and turned, expecting perhaps a black sea bass. I was worried that such a beast might cut this orgy short since they are known to feed on these crabs. Instead, it was a diver couple sitting at a respectable distance from me watching this display! They were very careful not to stir up the sand, which I greatly appreciated. Turned out they were both performers on the cruise ship in port that day. By the time I surfaced from my dive, they had told everyone in the park (not very many people this summer) about the X-rated filmmaker and his "porn" stars.

The crabs continued mating for a total of at least 15 minutes. Then the male seemed to lost his strength. He tried to hold on to the female, but she gradually worked her way out of his grasp and scurried off. The male tried to follow her, but not with the ardor he possessed before their coupling. I have seen a lot of sheep crabs in the dive park the past two or three years, but this was the first time I've ever seen (and filmed) them mating. Now I have them engaged in both of the primary activities of any species (feeding, of course, being the other).

Since I watched through my tiny viewfinder, it has been very helpful to edit and review the tapes afterwards to understand the finer details of the mating ritual. I posted a few images on the web site where I've developed quite a following thanks to my earlier video work on giant kelpfish and garibaldi mating behavior. I think most of that board's members (like myself) need a cold shower... or dive!

© 2004 Dr. Bill Bushing. Watch the "Dive Dry with Dr. Bill" underwater videos on Catalina Cable TV channel 49, 10:00 AM and 5:00 PM weekdays.

Male sheep crab pursuing female trying to escape; male clutching female at beginning
of encounter; actual mating; male (larger) and female in passionate embrace!

This document maintained by Dr. Bill Bushing.
Material © 2004 Star Thrower Educational Multimedia