Statistics in a Nutshell, 2nd Edition

Colophon

The animal on the cover of Statistics in a Nutshell is a thornback crab, also known as a spiny spider crab (Maja squinado, Maja brachydactyla). Found in the northeast Atlantic Ocean and the Mediterranean Sea, the thornback crab is the largest of the European crabs, with a carapace diameter of two to seven inches. It is easily identifiable by the two hornlike spikes between its eyes, and the six or so smaller spikes that extend from each side of its shell. The thornback’s body is reddish with pink, brown, or yellow markings, and its surface is also covered with small spikes, as the crab's name implies.

Thornback crabs are occasionally found on the shore, but they prefer depths of 90 to 600 feet. They are solitary animals except during mating season, when they form large breeding mounds. In years when their numbers are particularly abundant, they can be a source of frustration for lobster fisherman as they infest the lobster pots. Thornbacks are themselves fished for their delicious claw meat.

Male thornbacks are effective predators; their delicate-looking claws are actually quite powerful and can open small mussels to feed on them. Their claws are also double-jointed, so although it is generally safe for a person to hold crustaceans by each side of their shells, thornbacks are able to reach over their backs to pinch the offender. Females have smaller, less flexible claws and are thus more vulnerable to attack. To defend against their predators—which include lobsters, wrasses, ...