The California giant salamander (''Dicamptodon ensatus'') is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

salamander Salamanders are a group of amphibians typically characterized by their lizard-like appearance, with slender bodies, blunt snouts, short limbs projecting at right angles to the body, and the presence of a tail in both larvae and adults. All t ...

in the

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

Ambystomatidae Ambystomatidae is a family of salamanders belonging to the order Caudata in the class Amphibia. It contains two genera, ''Ambystoma'' (the mole salamanders) and ''Dicamptodon'' (the Pacific giant salamanders). ''Ambystoma'' contains 32 species a ...

. ''Dicamptodon ensatus'' is

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found else ...

California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the m ...

, in the western

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territori ...

. The species once additionally included individuals now belonging to the species ''D. aterrimus'' (

Idaho giant salamander The Idaho giant salamander, ''Dicamptodon aterrimus'', is a species of salamander. There are three closely related species to this taxon: ''D. ensatus'', (California giant salamander), ''D. copei'' (Cope's giant salamander) and ''D. tenebrosus'' ...

) and ''D. tenebrosus'' ( coastal giant salamander), under the common name Pacific giant salamander, which now refers to the genus and family.

Taxonomy

The Pacific giant salamander (''D. ensatus'') was thought to consist of three geographic populations, an

Idaho Idaho ( ) is a state in the Pacific Northwest region of the Western United States. To the north, it shares a small portion of the Canada–United States border with the province of British Columbia. It borders the states of Montana and Wyomi ...

isolates, a group in northern

, and a group in

Oregon Oregon () is a state in the Pacific Northwest region of the Western United States. The Columbia River delineates much of Oregon's northern boundary with Washington, while the Snake River delineates much of its eastern boundary with Idaho. T ...

and

Washington Washington commonly refers to: * Washington (state), United States * Washington, D.C., the capital of the United States ** A metonym for the federal government of the United States ** Washington metropolitan area, the metropolitan area centered o ...

. In 1989 genetic studies showed that the ''D. ensatus'' populations consisted of three species: the

(''Dicamptodon aterrimus'') in Idaho, and two highly divergent species with a narrow hybrid zone in California, the coastal giant salamander (''Dicamptodon tenebrosus'') (ranging from northern California to Washington) and the California giant salamander (''Dicamptodon ensatus'') (ranging from Santa Cruz County to

Mendocino County Mendocino County (; ''Mendocino'', Spanish for "of Mendoza) is a county located on the North Coast of the U.S. state of California. As of the 2020 census, the population was 91,601. The county seat is Ukiah. Mendocino County consists whol ...

). A fourth species of ''Dicamptodon'',

Cope's giant salamander Cope's giant salamander (''Dicamptodon copei'') is a species of salamander in the family Dicamptodontidae, the Pacific giant salamanders.Behler, J. L. and F. W. King. (1979) ''National Audubon Society Field Guide to Reptiles and Amphibians'', Kn ...

(''D. copei'' ), lives on the

Olympic Peninsula The Olympic Peninsula is a large arm of land in western Washington that lies across Puget Sound from Seattle, and contains Olympic National Park. It is bounded on the west by the Pacific Ocean, the north by the Strait of Juan de Fuca, and th ...

, Washington.

Habitat

The natural

habitat In ecology, the term habitat summarises the array of resources, physical and biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species habitat can be seen as the physical ...

s of ''D. ensatus'' are temperate

forest A forest is an area of land dominated by trees. Hundreds of definitions of forest are used throughout the world, incorporating factors such as tree density, tree height, land use, legal standing, and ecological function. The United Nations' ...

river A river is a natural flowing watercourse, usually freshwater, flowing towards an ocean, sea, lake or another river. In some cases, a river flows into the ground and becomes dry at the end of its course without reaching another body of w ...

s, freshwater

lake A lake is an area filled with water, localized in a basin, surrounded by land, and distinct from any river or other outlet that serves to feed or drain the lake. Lakes lie on land and are not part of the ocean, although, like the much large ...

s, and freshwater

marsh A marsh is a wetland that is dominated by herbaceous rather than woody plant species.Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p Marshes can often be found a ...

es in northern California. Dicamptodon ensatus terrestrial adult

Description

The adult California giant salamander can reach 17–30.5 cm (6.7–12 inches) in total length (including tail). Like most salamanders, the California giant salamander has four toes on the front feet and five toes on the back feet. The California giant salamander's tail is approximately 40% of the total length of the salamander and is laterally compressed. The head, back, and sides of the salamander have a marbled or reticulate pattern of dark blotches on a light brown or brassy-colored background. They have a broad head with a shovel-like snout and a fold of skin across the throat called the gular fold. The eyes are medium in size and have a brass-flecked iris and a large black pupil. This species is one of the few salamanders capable of vocalizing. Terrestrial adults search for prey such as snails, slugs, insects (such as beetles, caddisfly larvae, moths, and flies), other invertebrates, small mice (such as

white-footed mice The white-footed mouse (''Peromyscus leucopus'') is a rodent native to North America from Ontario, Quebec, Labrador, and the Maritime Provinces (excluding the island of Newfoundland) to the southwestern United States and Mexico. In the Maritimes, ...

), shrews, possibly reptiles, and other amphibians under surface objects and in tunnels, whereas aquatic adults and larvae eat aquatic invertebrates, fish, snakes, and other amphibians. California giant salamanders are preyed upon by the American water shrew (''Sorex palustris'') and the western aquatic garter snake (''Thamnophis couchi'').

Reproduction and development

The California giant salamander breeds from March to May, with egg-laying peaking in May. Eggs are concealed several feet below the surface in cold, slowly flowing water often beneath rocks and coarse woody debris in stream bottoms. Adults sometimes stay near their nests. Larvae may lose their external gills and transform to terrestrial adults after 1 to 2 years. In permanently perennial streams, adults may retain their gills and become aquatic adults. (See ''Neotenes'' below.)

Range

The California giant salamander is

to Northern

and lives up to primarily in damp, coastal forests including coast Douglas fir (''

Pseudotsuga menziesii The Douglas fir (''Pseudotsuga menziesii'') is an evergreen conifer species in the pine family, Pinaceae. It is native to western North America and is also known as Douglas-fir, Douglas spruce, Oregon pine, and Columbian pine. There are three va ...

var. menziesii'') and California coast redwood (''

Sequoia sempervirens ''Sequoia sempervirens'' ()''Sunset Western Garden Book,'' 1995:606–607 is the sole living species of the genus '' Sequoia'' in the cypress family Cupressaceae (formerly treated in Taxodiaceae). Common names include coast redwood, coastal ...

'') in both montane and valley-foothill riparian habitats. They tend to be common when they occur. The adult terrestrial form is found under surface litter and in tunnels, while the adult aquatic and larval forms are found mainly in cool, rocky streams and occasionally in lakes and ponds. It is found in two (possibly three) isolated regions. The first range includes Sonoma, Napa, and Marin Counties, southwestern Lake County, western

Glenn County Glenn County is a county located in the U.S. state of California. As of the 2020 census, the population was 28,917. The county seat is Willows. It is located in the Sacramento Valley, in the northern part of the California Central Valley. The ...

, and southern

. The other documented region is south of the San Francisco Bay from central

San Mateo County San Mateo County ( ), officially the County of San Mateo, is a county located in the U.S. state of California. As of the 2020 census, the population was 764,442. Redwood City is the county seat, and the third most populated city following Daly ...

to southern Santa Cruz County plus western

Santa Clara County Santa Clara County, officially the County of Santa Clara, is the sixth-most populous county in the U.S. state of California, with a population of 1,936,259, as of the 2020 census. Santa Clara County and neighboring San Benito County together f ...

. The California giant salamander does not occur in the East Bay, forming a gap between these two populations.Distribution map
iucnredlist.org There is an unconfirmed sight record from Big Sur in

Monterey County Monterey County ( ), officially the County of Monterey, is a county located on the Pacific coast in the U.S. state of California. As of the 2020 census, its population was 439,035. The county's largest city and county seat is Salinas. Montere ...

, approximately 75 miles (100 km) to the south of the documented population in the Santa Cruz area.

Neotenes

Some California giant salamander

larva A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. ...

e continue to grow into adults and become sexually mature without losing their external gills. This process is called

neoteny Neoteny (), also called juvenilization,Montagu, A. (1989). Growing Young. Bergin & Garvey: CT. is the delaying or slowing of the physiological, or somatic, development of an organism, typically an animal. Neoteny is found in modern humans compa ...

. Adult-sized neotenes have a uniform brown coloring on their heads, sides, and backs and retained external gills which allow them to live in perennial streams as aquatic adults.