'/' 



The mole crab Emerita I Hippa ) talpoida, more than 

 1 inch long, burrows in sandy beaches and sand bot- 

 toms on both coasts of America. Its feathery antennae 

 serve to strain food particles from the water. ( Dela- 

 ware Bay. William H. Amos) 



the edges of the carapace where the body wall is thin 

 and blood comes close enough to the surface to be 

 aerated. 



Beaches patrolled by ghost crabs at night are of- 

 ten the marshaling grounds by day of fiddler crabs 

 (Uca, Plate 100). Most fiddlers are less than 1 inch 

 from side to side and considerably shorter from front 

 to rear. Yet each male carries an absurdly big claw 

 (the "fiddle") on one side or the other. The "bow" is 

 the corresponding pincer-tipped foot on the opposite 

 side, used in feeding. 



Female fiddlers have two "bows" and no "fiddle." 

 They eat ambidextrously. Males use the oversize claw 

 in courtship gestures and in defense. Often, when the 

 big claw has been clamped firmly on an attacker, 

 the crab sheds the whole arm and scampers off. At 



The house centipede Scutigera forceps frequents damp 

 places in houses, where it preys on undesirable house- 

 hold insects. It rarely bites and should be welcomed. 

 (Vienna. Eric Sochurek) 



the next molt the loss is made good. On the damaged 

 side a new claw of "bow" size appears; and where 

 the crab had an undamaged "bow" it now has a new 

 "fiddle." In this way the fiddler crab changes its 

 handedness for feeding and courtship. And for this 

 same reason almost exactly half of the males in any 

 army of fiddlers is right-handed, the rest left-handed. 



MANTIS SHRIMPS 



Of all the crustaceans, the most intelligent may 

 well be the mantis shrimps (order Stomatopoda, 

 Plate 91). The bodies of these animals range from 2 

 inches long to somewhat more than 1 foot in the giant 

 SqiiiUa mantis. A few kinds are magnificently col- 

 ored. All of them suggest a lobster that has lost its 

 prominent antennae, its big claws, and the rear 

 portion of the carapace. The tail fan is not quite so 

 well developed. Yet when a mantis shrimp curls 

 its powerful abdomen under, it darts backward just 

 about as suddenly as any lobster or crayfish. In some 

 places, stomatopod tails are sufficiently easy to take 

 to be used as human food. 



Mantis shrimps are predators that creep about or 

 wait in a burrow mouth or an opening in a big 

 sponge, watching for a fish to come within reach. 

 Then the largest and most posterior of the mouth- 

 parts is suddenly opened like a jackknife, the blade 

 being the outermost segment. It fits into a groove in 

 the portion of the appendage against which it is 

 folded. 



In some mantis shrimps the blade is sharp and 

 smooth. In others it bears strong sharp spines. But 

 the snatching action with the blade is so fast as to 

 put to shame the praying mantis, the insect for which 

 these crustaceans were named. With its weapons a 

 mantis shrimp can slash a small fish in two or, es- 

 pecially if the stomatopod is large, inflict a very 

 severe wound. 



The stalked eyes of a mantis shrimp are freely 

 movable, not only in swinging motions that might 

 compensate for change in position of a mate or 

 some potential victim, but also through rotations. 

 This allows the animal to use different parts of its 

 compound eyes for examining objects nearby. To 

 everything in its surroundings a stomatopod is alertly 

 responsive. Quite quickly it accepts food and forms 

 associations in an aquarium, achieving these con- 

 ditioned reactions much more rapidly than the ghost 

 crabs which seem so eminently trainable on land. 



The Centipedes 



(Class Chilopoda) 



Every child learns to recognize a centipede as a 

 "hundred-legged worm." But not many people take 



