A hair-fringed breathing slit on ventral surface 

 between basal articles of third and fourth walk- 

 ing legs. 



Measurements. — Carapace: male, length, 44 

 mm. ; width, 50 mm. 



Color. — Gray, pepper-and-salt, grayish white, 

 pale yellow, straw color, or yellowish white im- 

 itating color of beaches; sometimes light amber 

 and often iridescent; yellow markings below and 

 and on legs; young mottled gray and brown 

 (various authors) . 



Habitat. — This species, the most terrestrial of 

 the decapod crustaceans in the Carolinas, lives in 

 abundance along the ocean beaches and sometimes 

 on harbor beaches. The crabs construct burrows 

 2 to 4 feet in depth from near the high-tide line 

 to distances up to a quarter of a mile from the 

 ocean. 



Type locality. — Jamaica. 



Known range. — Block Island, R.I., to State of 

 Santa Catarina, Brazil (megalops have been 

 taken at Woods Hole) . 



Remarks. — The ghost crabs are so large, accessi- 

 ble, and widely distributed that they have been 

 extensively investigated in various parts of their 

 range. 



Perhaps because of its mode of life, this animal 

 has left a fragmentary fossil record. Rathbun 

 (1935) recorded 0. quadrata questionably from 

 the Pleistocene of Florida. Hayasaka (1935) 

 compared the "sandstone pipes" commonly found 

 in certain Tertiary sandstones of Formosa to 

 plaster casts of burrows made by the Formosan 

 crab, 0. ceratophthalma, and found them to be 

 much alike. Burrows of the modern Formosan 

 and eastern North American species are similar. 



The egg-laying season in the Carolinas appears 

 to extend from April (Coues, 1871) to July. Ap- 

 parently the egg-bearing period is approximately 

 the same farther south at Tortugas, Fla. (Cowles, 

 1908), and farther north in New Jersey (Milne 

 and Milne, 1946). The latter authors pointed out 

 that ovigerous females differ in behavior from 

 other individuals in that they wade in water more 

 freely, run along on the bottom, and at intervals 

 when the water is quiet open the abdomen out, 

 flip upside down, extend the mouthparts, rotate 

 the legs, and, thus, force water through the egg 

 mass. Such females will run quickly to water 

 when disturbed. The free-swimming zoea of this 



species has not been described, but the megalops 

 was first described by Say (1817) as Monolepi-s 

 inermis. Smith (1873a, 1873b, 1880b) recognized 

 the true status of the form, and pointed out that 

 though this megalops is carried as far north as 

 Vineyard Sound by the Gulf Stream, that area is 

 apparently too cold to support an adult popula- 

 tion. 



Habits of O. quadrata have been treated in a 

 number of scholarly and popular works, but the 

 serious student is referred especially to Cowles 

 (1908) and Milne and Milne (1946). A popular 

 account of some value, except for the concluding 

 conjectures, was given by Phillips (1940). Only a 

 brief summary from these authors can be given 

 here. 



The young crabs are found close to shore. Bur- 

 rows of the young are near the water and extend 

 to water level or are covered by high tides for a 

 time, whereas older crabs burrow farther from 

 water; such burrows seldom are deep enough to 

 reach water level. Burrows are of three general 

 types : ( 1 ) a short vertical burrow made by young 

 crabs, (2) a burrow sloped downward at about 45 

 degrees away from the shoreline, often with a 

 vertical branch extending upward almost to the 

 surface, and (3) burrows higher on the beach, 

 much like the second type but without the vertical 

 side branch. In fall in New Jersey, the burrows 

 were found to be farther from water and far 

 deeper than any studied earlier in the year, and 

 it is presumed that a variety of sizes of crabs 

 hibernate in these deep burrows. 



Burrow making is primarily an occupation of 

 daylight hours. The crabs cease feeding on the 

 wet beach toward dawn. Those feeding on a fish 

 carcass often burrow within an inch or two of the 

 carcass. Young crabs near water make new bur- 

 rows, older ones range inland and build burrows 

 or occupy old holes. Sand is brought to the mouth 

 of the burrow and dropped or spread near the 

 opening in a fan-shaped area. Toward noon, 

 openings to burrows are plugged with damp sand, 

 thus concealing the burrow. Toward evening the 

 crabs begin to emerge again, and by 10 p.m. the 

 whole population is usually on the beach. 



These crabs are scavengers (and cannibals) and 

 tend to feed most actively along the drift line, 

 looking for beached fish or refuse and small bits 

 of food buried in the top layer of sand. The crabs 



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FISH AND WILDLIFE SERVICE 



