having a well-fitted shell stunts their growth. Because intact gastropod shells are
limited, shell competition is an issue.
Hermit crabs are decapod (which literally means “ten footed”) crustaceans. Of
their five pairs of legs, the first two are pincers, or grasping claws, the larger one of
which they use to defend themselves and shred food. The smaller claw is used for
eating. The second and third pairs of legs help them walk, and the final two pairs
help keep them in their shells.
Characteristic of crustaceans, hermit crabs do not have an internal skeleton but
rather a hard exoskeleton of calcium. They also have two compound eyes, two
pairs of antennae (which they use to sense smells and vibration), and three pairs
of mouthparts. Near the base of the their antennae is a pair of green glands that
excretes waste.
Sea anemones (water-dwelling, predatory animals) are often found attached to
hermit crabs’ shells. In exchange for transportation and a helping of the hermit
crab’s leftovers, sea anemones help to ward off the hermit crab’s marine preda-
tors, such as fish and octopus. Other predators include birds, other crabs, and
some mammals (man included).
Known as the “garbage collectors of the sea,” hermit crabs will eat mostly
anything, including dead and rotting material on the seashore, and thus they play
an important role in seashore cleanup. As omnivores, their diet is varied and
includes everything from worms to organic debris, such as grass and leaves.
The cover image is from Johnson’sLibrary of Natural History, Volume 2. The
cover font is Adobe ITC Garamond. The text font is Linotype Birka; the heading
font is Adobe Myriad Condensed; and the code font is LucasFont’s
TheSansMonoCondensed.Algorithms in a Nutshell
Algorithms in a Nutshell By Gary Pollice, George T. Heineman, Stanley Selkow ISBN:
9780596516246 Publisher: O'Reilly Media, Inc.
Prepared for Ming Yi, Safari ID: [email protected]
Licensed by Ming Yi
Print Publication Date: 2008/10/21 User number: 594243
© 2009 Safari Books Online, LLC. This PDF is made available for personal use only during the relevant subscription term, subject to the Safari Terms of Service. Any other use