Coastal giant salamander

The coastal giant salamander (Dicamptodon tenebrosus) holds the distinction of being the largest terrestrial salamander found in North America. This species is native to the Pacific Northwest region, with its range extending across Northern California, Oregon, Washington, and into southern British Columbia. It is closely related to other species within the genus Dicamptodon, including the California, Cope's, and Idaho giant salamanders.

Description and Life Cycle

Adult coastal giant salamanders are robust in build, featuring stout limbs with four toes on the front feet and five on the hind feet. Their tail constitutes approximately 40 percent of their total length and is laterally compressed. The coloration is distinctive, characterized by a marbled or reticulate pattern of dark blotches set against a light brown or brassy background across the head, back, and sides. A notable feature is the broad head with a shovel-like snout and a prominent gular fold across the throat. The eyes are medium-sized with brass-flecked irises and large black pupils. Uniquely among salamanders, the coastal giant salamander possesses the ability to vocalize.

This species exhibits a fascinating dual life history. They begin life as aquatic larvae, equipped with filamentous gills and an elongated tail featuring a caudal fin, similar to a tadpole. Upon metamorphosis, they transition into a terrestrial adult form, losing their external gills and caudal fin while developing robust legs and internal lungs. However, a remarkable phenomenon known as neoteny can occur, particularly in populations in British Columbia. In neotenic individuals, larvae become sexually mature without undergoing full metamorphosis, retaining their external gills into adulthood. These adult-sized neotenes typically display a uniform brown coloration.

Behavior and Diet

Terrestrial adult coastal giant salamanders are primarily fossorial, spending most of their time concealed underground in burrows. They emerge to forage and reproduce, typically on rainy and humid nights. As opportunistic feeders, their diet is varied. Adults consume a wide range of prey, including invertebrates such as slugs, insects, and worms, as well as small vertebrates like rodents and snakes, and even other giant salamanders. Larval stages focus on smaller prey, such as insect larvae, small fish, and mollusks. Cannibalism, with both adults and larvae consuming individuals of their own species, has been documented.

Defense Mechanisms

When faced with a threat, adult coastal giant salamanders employ several defense strategies. They will arch their backs and lash their tails forward. Furthermore, they possess the ability to excrete toxins through their skin, which can induce nausea if ingested. Additionally, they are capable of delivering a painful bite.

Habitat and Distribution

The coastal giant salamander's habitat preferences are tied to its life stage. Aquatic larvae are found in clear, cool, well-oxygenated mountain streams, and occasionally in mountain lakes and ponds. Metamorphosed adults inhabit humid forests, often seeking shelter under rocks and logs, and are typically found near mountain streams or along the rocky shores of mountain lakes.

Conservation

In British Columbia, Pacific giant salamanders, including the coastal giant salamander, are afforded protection under the Wildlife Act, which prohibits their killing or collection.