Description: The Idaho giant salamander is the darkest and most intricately blotched of the giant salamanders. They vary between brown, purple, tan, grey, and a copperish color. Tiger salamanders and Idaho giant salamanders have superficial resemblance pertaining to size and shape, but the costal grooves and foot tubercles are significantly different between the two species. This salamander has a defining thick head and body and a fourth toe on the hind foot with only three segments. Adults are typically 7.8 inches in length but often vary between 7 and 11.75 inches long and may be observed around 13 inches at maximum length.

Small external gills adapted for small stream living can be found on their larvae. Their larvae are usually tan with yellow blotches over their dermis. They can undergo paedomorphosis, but the ratio of terrestrial adults to paedomorphic adults is unknown due to sampling biases (most studies on the salamander are conducted in streams, where terrestrial adults are unlikely to be found).

Habitat: The habitat of the Idaho giant salamander is in the forests of northern Idaho and western Montana. Within these wooded areas, it lives in the small streams and marshy areas. The adult can can be found outside of the water near the streams living under rocks and logs, while the aquatic larvae will be located in streams that are at an estimated elevation of above 975 m. The depth of which it resides in has not yet been recorded. The adult will live under fallen logs and rocks within and along the streams and marshes. The adult female will lay its eggs under completely submerged logs and rocks and remain near this location until larvae reach adulthood. The elevation of where it lives has not been recorded, other than the elevation of its larvae.

Range: This species of salamander is found in forested watersheds from lake Coeur d’Alene to the Salmon River, and in two locations in Montana around Mineral County.

Found in these States: ID | MT

Diet: Larvae are predators but tend to sit and wait for their food to come to them. Usually they feed on small invertebrates and some small vertebrates. This can include tadpoles, fish, and other salamanders. Adults usually feed on terrestrial vertebrates and invertebrates. They will eat things as large as shrews, mice, and small snakes, along with other salamanders. They will eat anything that they can catch.

Reproduction: Breeding occurs in mountain stream headwaters, or in montane lakes. Egg deposition occurs in submerged nest chambers under logs and rocks or in water-filled crevices within submerged rocks.

Status: Listed as Least Concern in view of its wide distribution and presumed large population.

Taxonomy: