As a production editor at O’Reilly, one of the best things about wrapping up a book is being able to write the colophon, which describes the animal that appears on the cover. Here’s a sneak peak at the one I just finished for SQL Tuning:
The animal on the cover of SQL Tuning is a salamander. Though mature salamanders bear a superficial resemblance to small lizards, salamanders are not reptiles; rather, they are amphibians that retain their tails as adults. Like all amphibians, a salamander begins life underwater as a gelatinous egg and develops through a series of stages. Newly hatched salamander larvae resemble tadpoles (the larval form of toads and frogs) and breathe through gills. As they mature, salamanders develop legs and lungs, which allow them to leave the water and breathe air. But they remain in or around streams, rivers, ponds, lakes, or moist woodlands throughout their lives. They must return to a freshwater source to lay their eggs.
The most immediately recognizable difference between adult salamanders and lizards is the former’s lack of scales; a salamander’s skin is smooth and porous and is used to absorb moisture. Salamanders’ skin can be any of a variety of colors–from brown or black to yellow or red–and is often covered with dark spots, bars, or stripes. As they grow, salamanders molt their skin, usually every few days or every few weeks. Salamanders also have the ability to shed and regrow their tails and other parts of their body that become severed or damaged. Unlike other amphibians, salamanders are carnivorous at every stage of their life cycle (tadpoles are herbivorous), and their diet consists of worms, insects, snails, and small fish.
Mature salamanders are usually about 4 to 8 inches long, though they can be as short as 2 inches and as long as 70 inches. Most have four legs, though some have only two forelegs. Their front feet each have four clawless toes, while hind feet, when present, have five toes. Salamanders are nocturnal and usually divide their time between the land and water, though some live exclusively in the water and a few are purely land-dwelling. When they swim, they make little use of their limbs. Instead, they use their laterally compressed (i.e., taller than it is wide) tail and muscle contraction to propel themselves through the water, as eels do. Some tree-dwelling salamanders have prehensile tails, which they can use to grasp branches.
The name salamander (from the Greek salamandra) originally applied to a legendary creature that could live in and extinguish fire. Aristotle is largely responsible for perpetuating this myth; in his History of Animals, he supports the story that the salamander “not only walks through the fire but puts it out in doing so.” The application of the name salamander to an actual amphibian was first recorded in 1611, at which time the supernatural characteristics of the mythological animal became attributed to the actual animal. The common belief (mistaken, of course) that salamanders can endure fire persisted well into the 19th century.
If you’re interested in reading a few of my colophons from past books, check out Object-Oriented Programming with Visual Basic .NET (double-breasted cormorant), Content Syndication with RSS (American kestrel), Java Data Objects (bilby), Essential CVS (bobacs), and Mac OS X Hacks (adjustable wrench; books in the Hacks series feature photographs of tools instead of drawings/engravings of animals).