A fair amount of confusion still persists among the general public as to what is an amphibian and what is a reptile. Some of this uncertainty may stem from the name of the discipline that addresses these two groups: herpetology. This term is derived from the Greek word herpeton, which translated means “a crawling animal.” Snakes, legless lizards, and caecilians (the legless group of amphibians) do indeed crawl, and some salamanders and lizards may also appear to do so. However, by present-day taxonomic standards this is certainly not a sound feature by which to justify the clumping of these two...

Because of the secretive nature of many salamander species and because some groups such as the mole salamanders are above ground for a very short period each year, the recognition of their eggs and, where appropriate, aquatic larvae is a useful field identification tool. We therefore have included illustrations of eggs for most species and larval illustrations for aquatic-breeding forms with the color plates of the adults at the beginning of each natural history account. Figure 22 shows the capsular chamber and gelatinous envelopes that surround the amphibian ovum and whose position, shape, and number vary between species or similar...

Tailed frogs are members of an ancient group of anurans. The closest relatives to our Pacific Northwest species are three “tail-less” species in New Zealand. These frogs are named for their tail-like copulatory organ that facilitates internal fertilization by copulation, a method of breeding unique among anurans. It inhabits cold streams, where its larvae live in torrents or quiet water and cling to rocks with their large, suckerlike mouths. Larval development to metamorphosis requires from two to four years, depending on the temperature of the larval habitat. Adults do not breed until their seventh or eighth year.

Identification: adults range...

In our introduction to the amphibians we highlighted the landmark stage in vertebrate evolution some 400 million years ago, when a group of shallow-water fishes acquired anatomical and behavioral features that enabled them to explore shoreline habitats and ultimately give rise to the first tetrapod vertebrates. In contrast to this scenario, the evolution of reptiles from what was most likely a common ancestral form for both reptiles and amphibians entailed no such dynamic transformation but instead progressed as a gradual accumulation of features that allowed many members of this new group of terrestrial vertebrates to no longer be dependent on...

Most lizards and snakes are quite different from one another, and it may be surprising to some people that they are grouped in the same order along with one other small legless suborder, the worm lizards (Amphisbaenia). However, upon close inspection, it is hard to find even one sound feature that separates these two major groups. The one that may first come to mind, the presence or absence of legs, is not satisfactory, because although no snakes have fully formed legs, there are several legless lizard species, including one in California, the California Legless Lizard (Anniella pulchra). Features shared in...

To date (2011) about 4,770 species of lizards have been described. This suborder is worldwide in distribution, and its members have adapted to many different environments. Most are terrestrial, but many are arboreal and several are semimarine. A few species even engage in gliding flight, using “wings” formed from a membrane stretched between elongate free, extensible ribs. There are also forms that have adapted to a burrowing life and in the evolutionary process lost all four limbs. However, the great majority of lizards have two pairs of well-developed limbs, with five digits bearing claws on each foot. Many species are...

Close to 3,000 species of snakes have been described. Despite their lack of limbs, they have become adapted to most major habitats and are distributed nearly worldwide. The majority are terrestrial, but some are arboreal, fossorial, or aquatic. In the absence of limbs there is considerable restriction in the variability of bodily form. Nevertheless there are obvious modifications related to habits. The smallest of California snakes, the Western Blind Snake (Leptotyphlops humilis), is cylindrical with a short blunt tail, no ventral plates or scutes, and vestigial eyes. Loose soil burrowers like shovel-nosed snakes (Chionactis) have nasal valves, a countersunk lower...

About 175 million years ago in the Jurassic Period, this group of reptiles acquired through the natural selection process a structure that has been so successful that their basic body form has changed little since that time. That structure is a shell composed of two parts: an upper rounded carapace and a flatter ventral plastron, connected on each side by a bridge. It accrued to this group a universal mode of protection that has effectively deterred predators from the age of reptiles through the advance of the mammals and birds. There are currently about 335 living species of turtles arranged...