Ambystomatidae

The Ambystomatidae consists of 32 species that range from Mexico through the United States, and into Canada. All ambystomatid salamanders lay eggs, which hatch into an aquatic larval stage. The aquatic larvae have feathery external gills and are carnivorous. They'll eat small invertebrates, tadpoles, and even other salamanders.

Amphibian deformities can be caused by both natural events and human activities. Specific environmental conditions during an amphibian's larval stage can disrupt its development and cause diverse types of deformities of the legs and toes. Disruptions during the larval stage from anthropogenic pollutants can also prevent normal development of reproductive organs in amphibians, resulting in amphibians that cannot reproduce.

One of the most fascinating aspects of Ambystoma is the existence of all-female, clonal-reproducing, sperm-stealing Unisexual Ambystoma.

Salamandridae

The Salamandridae are often toxic and brightly colored. They have a nearly worldwide distribution. Two genera are found in North America: Taricha and Notophthalmus. Taricha are large-bodied newts found on the west coast of North America, while Notopthalmus are much smaller and found in eastern North America.

The most widespread Notopthalmus is the Eastern Newt, with a geographic range stretching over much of eastern North America. The other two species have much smaller geographic ranges and are either threatened or endangered.

Eastern Newts (Notopthalmus viridescens) have one of the most complex amphibian life cycles. All Eastern Newts start their lives as aquatic eggs that hatch into small, aquatic larvae. Like other species of salamander, newt larvae have external gills. In many populations, the newt larvae develop for a few months before metamorphosing and moving onto land. The terrestrial stage is known as the "eft" stage. Efts are typically bright red with rough skin. Several years will be spent living on land in the red eft stage. As the efts reach adult size, they migrate into wetlands and undergo another transformation. Although they keep their small red spots, the rest of their red coloration turns into a more cryptic olive color. The adults will then mate in the wetlands, keeping the cycle going.

The newts of the genus Taricha are found along the Pacific coast of North America. Two of the species are found only in California: the California Newt and the Red-Bellied Newt. One species is found from northern California into British Columbia: the Rough Skinned Newt. You can tell apart the Taricha species by a combination of geographic range, color pattern, morphology, and behavior.

Taricha newts are toxic, and have been the source of human fatalities through both accidental and intentional ingestion.

Plethodontidae

With over 460 recognized species, Plethodontidae is the largest family of salamanders. It also contains some of the greatest diversity of life-history habits. Some have a larval stage, some skip the larval stage, and some retain larval traits as adults. However, one key trait unites all Plethodontidae: they completely lack lungs.

There is some debate about whether Plethodontidae should be separated into two major groups or four major groups. Here, I will group these salamanders by four major groups: Hemidactyliinae, Bolitoglossinae, Spelerpinae, and Plethodontinae.

Hemidactylinae

This subfamily contains just a single species, the four-toed salamander: Hemidactylium scutatum. They are found in populations scattered across eastern North America. They have an interesting communal nesting behavior, in which females will guard her own eggs, plus the eggs of unrelated females. After hatching, the young four-toed salamanders go through a brief aquatic larval stage before metamorphosing to live on land.

Bolitoglossinae

Although there are about 310 species in the Bolitoglossinae, most of the diversity of this group is found in Central America and South America. In the United States we have only one representative of this group: the genus Batrachoseps. Commonly known as "Slender Salamanders", Batrachoseps have long, thin bodies.

Spelerpinae

The members of this group are confined to the eastern United States and Canada. All of them share an aquatic larval stage. In some species, the adults keep many larval characteristics like gills, and remain fully aquatic as adults. This group also includes several species that have adapted to life in caves.

Spring salamanders (Gyrinophilus porphyriticus) are one of the largest members of the Plethodontidae. They inhabit streams as larvae and adults.

Tennessee Cave Salamanders (Gyrinophilus palleucus) have adapted to life within caves, and are closely related to Spring Salamanders.

The genus Eurycea includes two-lined salamanders, cave salamanders, long-tailed salamanders, and some amazing cave-dwelling species.

Plethodontinae

The Plethodontinae is primarily found in North America, but there are a few species in Europe, and at least one species in Asia.

The genus Plethodon . . .

The genus Ensatina consists of a single species with direct development. Ensatina range from southern British Columbia to northern Baja California. They are most famous for being a classic example of a ring species.

The web-toed salamanders Hydromantes are found in western North America. All have direct development. They are also famous for being able to fire their tongue an incredibly long distance to capture prey.

A related group of salamanders in the genus Spelomantes are found in Europe. Some biologists still consider Spelomantes to be part of Hydromantes.

The genus Aneides consists of six species scattered across North America. One species is found in the eastern United States, another species is found in New Mexico, and the remaining species are found along the pacific coast. All Aneides have direct development from egg to juvenile with no larval stage.

Rhyacotritonidae

There are only four members of the family Rhyacotritonidae, all members of the genus Rhyacotriton. They are limited to the pacific northwest of North America.