. Elementary textbook of economic zoology and entomology. Zoology; Insect pests. CRAYFISH, LOBSTERS, CRABS, SHRIMPS, ETC. 121 twelve to sixteen feet across the extended legs, the body itself being but little more than a foot in width or length. The fiddler crabs, Uca spp., so common along the Atlantic coast, are the clowns among the crabs. The males have one of the chelae very much enlarged, and when alarmed they move this swiftly back and forth with a motion ridiculously like that of a violinist with his bow. The blue crab, or "soft-shelled" crab, Callinectes hastatus, is the most i
. Elementary textbook of economic zoology and entomology. Zoology; Insect pests. CRAYFISH, LOBSTERS, CRABS, SHRIMPS, ETC. 121 twelve to sixteen feet across the extended legs, the body itself being but little more than a foot in width or length. The fiddler crabs, Uca spp., so common along the Atlantic coast, are the clowns among the crabs. The males have one of the chelae very much enlarged, and when alarmed they move this swiftly back and forth with a motion ridiculously like that of a violinist with his bow. The blue crab, or "soft-shelled" crab, Callinectes hastatus, is the most important as a source of food on the Atlantic coast. On the Pacific Coast a much larger crab, Cancer magister, is taken in shallow waters, sometimes in considerable numbers, and is much prized. The horseshoe crab, or king-crab, Limulus, common all along the Atlantic coast, is really not a crab at all, nor even a crus- tacean, but belongs to another class, the relationship which is uncertain. Many believe that Limulus is most nearly related to the spiders. The beach fleas, order Amphipoda, are perhaps the most numerous crus- taceans found on the sea beaches, oc- curring in countless numbers in the tossed up seaweeds and mosses and other sea wrack. They are important as food for other marine animals. The boring Amphipod, genus Chelura, works on submerged timber, often , . , , r j FIG. 46.—A sow-bug, doing a great deal of damage. isopod, species not deter- The wood-lice or sow-bugs, order mined. Isopoda, are among the few crus- taceans that live a wholly terrestrial life. They live in moist places, feeding chiefly on decaying vegetable matter, but sometimes attacking tender plants and doing more or less damage in gardens and green-houses. Although land animals, they breathe by means of gills which are situated on the under side of the abdomen. It is therefore necessary for them to live in places where the gills may be kept damp in order that there may be a ready transfer of gases
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