I took this photo on my way to the beach at 5:30 am on June 22, 2013. Low tide would occur about 30 minutes later, at 6:06 am. The tide forecast was -2.3′ below mean lower low water. On this part of the coast you’ll almost never see a lower low tide, so this was a great opportunity to explore a sandy beach way out in the infralittoral fringe, the lowest intertidal zone. I have previously described this zone in Finding Yourself in the infralittoral Fringe. In that case, I used organisms attached to rocks as landmarks to the intertidal zones. This beach, however, has no rocks, just an expanse of featureless sand. Thus, no distractions.
Wrong. There were distractions all over the place; thousands of little distractions. This is the California beach hopper, Megalorchestia californiana and you are looking at the first photo I ever took of one. My only other attempt to find and photograph them was foiled by strong winds and I ended up writing River of Sand.
Beach hoppers are amphipod crustaceans and Megalorchestia californiana is the largest TOS beach hopper. They get about an inch long and big ones have fantastic antennae. M. orchestia is easily identified but there are other hoppers on the beach. Of those Ricketts and Calvin observe, “Anyone who consults the standard systematic literature will find the descriptions too intricate for an untutored mind…”. You’ve gotta love that.
Megalorchestia spend the day in burrows and under objects in the upper reaches of the beach, up in the fine sand and higher wrack indicated by the black arrows in the photo above. At night they emerge to forage and some may venture a bit lower on the beach, especially if there is seaweed in the wrackline, as in the lower central part of the photo. By dawn those that ventured down to wet sand have returned and are high on the beach again. Shortly after first light they all disappear into pre-existing burrows, or they dig new new ones. The burrows of M. orchestia are elliptical in cross section.
Kozloff says, “Where M. californiana is really common, the beach is a pretty lively place after dark…” From what I observed, he is right. I hope the images below convey the activity of these cute little hoppers scurrying and exploring.
If you want to know more about M. orchestia, consult the Walla Walla University species account. And if you haven’t done so already, you’ve got to check out Ingrid Taylar’s wonderful photos of California beach hoppers from Mendocino Beach, California.
My encounter with with M. orchestia was a pleasant distraction but I did end up missing the lowest part of the low tide. It was worth it. If you ever get a chance to plan a California beach hopper field trip, look for a beach with plenty of backshore (a wide shallow beach) backed up by dunes. If you find such a beach, look for some decaying seaweed in the wrackline. I had good luck in June, so maybe that’s a good time of the year. You can find large numbers of M. orchestia during the day by turning clumps of decaying seaweed or other materials, but if you want to see their wonderful behavioral antics, including interactions with each other, you’ll want to be on the beach at night or in the pre-dawn hours, no later than dawn.
Mike Westphal, my frequent TOS collaborator, sent a great California beach hopper video he took with his iPhone. If you love beach hoppers, check it out.
Kozloff, E. N. 1993. Seashore Life of the Northern Pacific Coast. 3rd ed. University of Washington Press.
Light, S. F., 2007. The Light & Smith Manual: Intertidal Invertebrates from Central California to Oregon. 4th ed., edited by J. T. Carlton. University of California Press.
Ricketts, E. W., and J. Calvin. 1968. Between Pacific Tides. 4th ed., revised by J. W. Hedgpeth. Stanford University Press.