23 April 2011

Horseshoe crabs mating

Earlier this week when we were in Tarpon Springs, Florida, we saw horseshoe crabs at a beach. A couple appeared to be mating: they were traveling together one behind the other. They kept beaching themselves and then turning around and heading back to deeper waters to escape from the curious people approaching them.

Yesterday, we were on Sanibel Island further south along the west coast of Florida. We visited the J. N. "Ding" Darling National Wildlife Refuge. There we saw more mating horseshoe crabs. This time they were in murky waters. Note the mud accumulated on the backs of the crabs.

Also note that the crab in the back in both pairs, presumably the male, is slightly smaller than the female in the front. This sort of sexual size dimorphism is especially common in aquatic animals. Larger females probably cope with the demands of egg production better than do smaller ones.


xoggoth said...

It's wierd but dumb invertebrates do seem remarkably aware of anything unusual in the vicinity.

I was trying to video a Whirlygig beetle on a pond today and got nowhere. Everytime I got in a decent position, no matter how still I was, it disappeared under an overhanging rock. As soon as I left out it came again.

Annoying little sod. Being a professional naturalist must be the most frustrating profession there is.

x said...

That's probably why you prefer snails. At least they can't gallop off.

Joy Window said...

We have only fossil forms of horshoe crabs in Australia. I was enthralled to meet living ones on my trip to the Georgia coast a couple of years ago.

Yalud said...

I find the horseshoe crab really interesting, especially as I only found out about them a few years ago in small musuem in batemas bay, australia.. nice photos..