IN 1585 SIR Francis Drake, whose purpose it was to harass Spaniards wherever he could find them, was lying in ambush with a detachment of harassers on the island then called Santo Domingo and now, in the official parlance of the United States, Hispaniola. The sound of hoofbeats resounded from the strand, emanating Sir Francis judged, from a body of cavalry too large to be affronted. He ordered quick retreat and must have felt a little foolish when his men emerged on the beach to discover they had been routed by a company of noisily scampering land crabs.

Land crabs exist in most of the warm waters of the world, especially on the west coast of Africa and in the Caribbean, which is the area where they are most prized for food. The low esteem in which they are held in some circles (and it is true their flesh is less firm than that of sea crabs and, being slightly rubbery, demands diligent chewing) accounts for the refusal of Floridians to eat them, though they are plentiful in Florida. In Puerto Rico they are considered a great delicacy. It helps, no doubt, that they are treated there with particular care. Shut up in wire pens when caught, the are simultaneously purged and fattened for three days before being delivered to the kitchen. Their first day's diet consists of coconut meat, the second's is corn and water, and the third is dry corn alone. On the fourth day they are ready for the table.

Puerto Rico is partial to stuffed land crab, for which the crustacean is first boiled. The meat is then removed from the shell, cut into small pieces and sauted with one or another of a number of possible combination of seasonings before being packed back into the shell for serving. Puerto Rico calls land crabs jueyes .

Despite its label, the land crab is at heart a sea crab; the place of all crabs is in the sea. True land crabs have alienated themselves from their original medium to the extent of developing enlarged body cavities which can breathe -- air like lungs -- though as a rule crabs breathe by means of gills; nevertheless they return to the sea when it is time to lay and fertilize their eggs. Having done so, the adults return to land, while the eggs they have left behind them hatch into larvae and pass through all the first stages of the animal's development in the water, which they leave for dry land only after they have become full-fledged crabs.

The coconut crab, so called because that is what it eats, also known as the robber crab because from the human point of view it steals nourishment from men, the tree crab and the palm crab because it climbs trees and the purse crab from its shape (and to zoologists as birgus latros ), does not belong to the ecrcinidae, but it is a true terrestrial crustacean, widespread in tropical Asia, Malaysia, Australia and the islands of the Pacific. It is a relative of the hermit crab and thus ought to be dragging itself about in a borrowed shell; it is, in fact, the only member of its group which does not do so. It would be hard for birgus latros to find a discarded shell of its kind. The length of its body, not counting the claws, sometimes reaches 18 inches. Carrying around a possible ill-fitting shell would also be cumbersome in the prusuit of its favorite food, the coconut: The crab spends the day in burrows in the ground coming out at night to climb coconut palms. It cuts young coconuts from the trees with its powerful pincers, which would also be inconvenient if the coconut crab, like the hermit crab, had a tender naked abdomen which would rake against the rough trunks of the palms as it climbed, so it has grown protective scaly plates over the upper part of it. The pincers and the legs, proportionally fatter and stronger than those of most crabs, and oriented farther forward, facilitate tree climbing. This presents us with a rather remarkable example of natural adaptation when we consider the robber crab alone, but to this is added what we might call a case of tandem evolution when we look at the crab in association with its food. The coconut, a good floater, has spread from island to island in obedience to the whims of ocean currents, winds and waves. The coconut crab, which like other land crabs, lays its eggs in the sea, produces from them larvae which stay afloat for a considerable time: the tide carries the larvae wherever it carried the coconuts on which they propose to feed.

English-language reference books will tell you that the coconut crab belongs to the anomura family ; French ones classify them as cenobitidae. This sounds like the sort of literary-classical reference dear to the well-read French. The idea seems to be a parallel between the hermits who lived alone in the rigors of deserts or other unattractive dwelling places and the cenobites who were distinguished from them by their choice of monasteries in which they could enjoy the society of their brother monks in a reasonably comfortable, well-organized group. The association with the hermit crab who lives in the sea and the coconut crab which has deserted its dangers for the possibly less perilous habitat of firm land seems a trifle far-fetched; whether the land crab is more or less gregarious than the hermit crab I don't know; it is probable that whoever thought up this name for the former didn't know either.

One would expect a crab that lives on coconuts to be pleasantly flavorful, but robber crab seems to be an acquired taste. Natives of coconut-palm coasts think highly of this animal's flesh, but Westerners previously unaccustomed to it usually find it oily.

The crustacean called a land crab in Austrailia is not a crab, but a crawfish, eugaeus fossor, which lives in holes it digs in the ground like the Louisana crawfish, which, however, belongs to a different genus, cabarus.