18 of 100: Crayfish

Yesterday afternoon we went on our regular dog-walk around the Del Rey Oaks Frog Pond near our house. Three-quarters of a mile, the trail passes through a willow woods, beneath an oak upland, and past a tiny redwood grove. You can see it on this map at the left, the area labeled MPRPD, which stands for Monterey Peninsula Regional Parks District, the blue splotch being the Frog Pond. We tend to do our walk as a figure-8, as shown on the map.

At the lower left edge of the pond, there's a wooden deck, which we usually stop at to enjoy the ducks dabbling or the great blue heron fishing; sometimes there's a kingfisher up on a branch, or a phalarope spinning in the water. These days, the pond is rapidly drying out, and is covered with reddish water fern/duckweed: it's a seasonal pond, and by next month will be completely dry, only to be filled with water again come the November or December rains. (It's probably less than a foot deep at its fullest.) Here's a photo from February 2022; the deck is on the left:

Anyway, today we stopped at the deck, and were rewarded with no ducks, no herons. But just below us at the edge of the duckweed, we saw movement. Lots of it. At first we thought it might be tiny Pacific tree frogs wriggling their way loose, but no: the movement was too big. Then David spotted some "arms" or "legs." These creatures were pretty large. And there were a lot of them! Finally, one crawled out onto the surface:

And we realized: we have crayfish in our pond!

Now, we've lived here for over thirty years, and walked the dog here probably 200/365 days of the last 13 years, and never once have we seen a crayfish in our pond. I was blown away! 

We had just been discussing what we'd have for dinner, and I was somewhat tempted by David's suggestion that we hustle on home (it's a five-minute walk) and get a net, but no. It's a park. And these crayfish deserve to live—however the hell they got here.

But it did, of course, get me wondering—about crayfish. Here's what Wikipedia has to say: "Crayfish are freshwater crustaceans belonging to the infraorder Astacidea, which also contains lobsters. Taxonomically, they are members of the superfamilies Astacoidea and Parastacoidea. They breathe through feather-like gills. Some species are found in brooks and streams, where fresh water is running, while others thrive in swamps, ditches, and paddy fields." As for numbers, there are four families of crayfish, three in the Northern Hemisphere. The greatest diversity of crayfish species is found in southeastern North America, with over 330 species in 15 genera, all in the family Cambaridae. The crayfish we find here in California were introduced, and have naturalized. (Here is a better picture than my iPhone snap, this of a red swamp crayfish, Procambarus clarkii, which may or may not be our local denizen.)

I have seen, very infrequently, crayfish in the nearby Lake El Estero, which lies between the Frog Pond and the ocean, all connected by a creek. I wonder if these crayfish somehow swam up from the lake? I can't imagine how they would have got to our pond otherwise. So strange! So wonderful! 

And yet... also "exotic." So maybe I should be putting them in the same category as the red-eared slider turtle I spotted the other month (and once again since): that is, not welcome. I don't know. Life will live. If the turtles and crayfish managed to get to our little pond—which not so long ago was a cow pasture, only to be flooded by human engineering projects—well, more power to them. (Then again—what I get from continuing to research: a statement to the contrary.) Who knows. We humans have done a great job of disrupting all balance everywhere, even in our own realm. Crustaceans in man-made ponds would seem to be the least of our problems...