"So, naturalists observe, a flea has smaller fleas that on him prey; and these have smaller still to bite ’em; and so proceed ad infinitum."
- Jonathan Swift

June 24, 2010

June 24 - Zaops ostreum

How many kind of food can you name comes with its own side dish? Well, the eastern oyster (Crassostrea virginica) should be on that list. This week. we've already seen how a trematode infection can improve the taste of oysters, but it seems that oyster also comes with another gastronomic treat in the form of the pea crab Zaops ostreum. Pea crabs (family Pinnotheridae) are small soft bodied crabs which live inside a variety of marine invertebrates, with most species living in bivalves. Zaops ostreum infect the oyster as a tiny first stage larvae, and grow to maturity within the bivalve's mantle cavity, feeding upon food-laden mucus strings produced by its host's filtering action. It is a true parasite in that it causes harm to its host. Not only does it steal food from the oyster, it also forms an obstruction within the body cavity and erode the gill tissue. From a culinary perspective, there are many serving suggestions available for pea crabs - they can be served raw, deep fried, or sautéed, and can be eaten either as a side dish to oysters, or even on their own (if you can get enough of them to make a meal!).

Photo and contribution by Tommy Leung.


  1. So they can be eaten raw without harm to humans, correct? I just found two in a dozen of recently-purchased oysters, intended for raw consumption. They are still alive. Can I safely down these little crabs raw and alive?

  2. I would recommend that you cook them first because they are known be have some of their own parasites, but there's no reason you can't eat them as you would other crabs.

  3. Thanks for your reply, Tommy. Funny, because after two days, I have now found them to be incredibly unappetizing, covered in slime and all (yes, they're still alive in my room inside a bottlecap I filled with tap water). I don't know why I ever had the impulse to down them raw...probably my good sense was skewed in the heat of the moment with company. I did have a concern that these pea crabs would have parasites of their own. As the crabs are still alive, I'm going to donate them to the biology department at my local university tomorrow (better than flushing them down the toilet, I suppose).

  4. Donating them to the local university would be a great idea - I am sure they will appreciate that interesting addition to their crustaceans collection!