[Pacific rock shrimp; Camarón de piedra del Pacífico,
Cacahuete (Spanish); Sicyonia ingentis of family
Sicyoniidae]
These shrimp are native to the coast of California and Baja California, from Monterey Bay as far south as the Isla María Madre, well off the southern tip of Baja, and in the Gulf of California between Baja and the mainland. They are characterized by a hard ridge down the back of their body and very hard, strong shells.
They have long been caught in trawls for rock fish, and were discarded because they were hard to shell, but they now have a good market due to their excellent flavor. They are, however, still a problem shrimp because they decay so rapidly once dead, so they need to be kept alive.
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The big disadvantage of these shrimp is that the moment they die, they start to digest their own internal organs, which quickly turn into black mush. Of the photo specimens, the top one has degraded significantly. If the internals have turned black, but not for too long, the tail meat is still excellent after shelling and cleaning up.
Preferably these shrimp are kept alive until tossed into boiling water. The preferred way of eating them is to pull off the head, suck out the juices, then shuck the tail for the meat.