Sunday, 6 February 2011

Baby Skates

This is an egg case from Raja binoculata, the big skate. This one has dried down to about the size of a really large fried egg; when fresh, supple, and translucent green, they're much larger. (Those of the less common Bathyraja trachura are neater and smaller.)

Skates are chondrichthyoids, cartilaginous fish related to sharks and sawfish, and closely resemble rays. When I was a kid, skates' eggs were common on the beach. I once found one still alive, with a wriggling embryo I could see inside when I held it up to the sun. I wanted to bring it home and hatch it in a five-gallon bucket, but my long-suffering mother put her foot down. The house was already crawling with my animals; I guess a baby skate was more than she thought I really needed.

We used to see dead skates on the beach a lot, but these days it's become fairly rare. I'm not sure why. Given the great strides in reducing pollution and overfishing on this coast over the last three decades, I incline toward an oceanographic hypothesis. That our currents have changed is obvious; the beach was eroding when I was young, and now it's accreting. And of course there's the global warming trend, bringing competing life forms north and driving incompatible ones elsewhere. Or killing them off entirely, when we're particularly unlucky.

Whatever the reason, I guess this is one fewer "doormat" we'll have swimming around one day.

Too bad. Skates rock.

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