These pictures show a recently-decapitated female Coastal Giant Salamander in Mendocino County. You can see her unlaid eggs spilling out of the wound. After they are produced and before they are laid, the eggs fill up the salamander's body cavity.
Coastal Giant Salamander larvae shown walking and swimming in shallow water and on streamside stones.
You can see the gills working on this tiny larva shown underwater in a small aquarium.
Adults are 2 1/2 to 6 4/5 inches long (6.25 - 17 cm) from snout to vent, and up to 13 inches (34 cm) in total length.
Neotenic larvae may grow to almost 14 inches (35 cm.)
This is the largest terrestrial salamander in North America.
(Hellbenders are much larger, but they spend most of their adult lives living in water.)
The body is large and robust with a massive head and stout limbs.
The tail is flattened from side to side.
Transformed adults have 12 - 13 indistinct costal grooves.
Larvae are stream-type with tail fins that extend forward only to the hind limbs.
There is often heavy black mottling.
Gills are short, bushy, and dull red.
Color and Pattern
The ground color of the body is dark brown to near black overlaid with light brown spotting or fine-grained marbling that gives the salamander a camouflaged appearance.
Very old animals may lose their pattern except on the head.
The venter is white to light gray, sometimes dark.
Comparison With California Giant Salamander
Dicamptodon ensatus, California Giant Salamander, is very similar in appearance to D. tenebrosus.
As far as I can determine, the only field mark that is useful to tell one species from the other is the presence of marbling on the chin and throat of D. ensatus, which is absent on D. tenebrosus, and possibly the underside, which is whitish on D. ensatus and gray to tan on D. tenebrosus.
According to Stebbins & McGinnis 2012, both species are similar in body length but D. tenebrosus has a
smaller head, shorter limbs, fewer teeth in the uper jaw, a darker body color both dorsally and ventrally, and the marbling pattern tends to be finer.
Stebbins, 2003, says that the "dark marbling and flecking usually does not extend onto underside of throat and limbs" and that there are "dark flecks and blotches on throat and underside of legs" of D. ensatus and that "Marbling on chin notable in southern part of range."
Fellers and Kuchta in
Amphibians of the Pacific Northwest, 2005 state it this way:
On D. ensatus:
"Marbling or blotching on lower jaw often extends onto the chin, throat and underside of the forelimbs and pectoral girdle."
On D. tenebrosus:
"Adult Coastal Giant Salamanders do not have marbling that extends beyond the lower jaw onto the chin or throat.
Life History and Behavior
A member of family Dicamptodontidae - Giant Salamanders, and the genus Dicamptodon - Pacific Giant Salamanders, whose members are large in size with heavy, stocky bodies.
Dicamptodon have two distinct life phases:
- Larvae are born in the water where they swim using an enlarged tail fin and breathe with filamentous external gills.
- Aquatic larvae transform into four-legged salamanders that live on the ground and breathe air with lungs.
Neotenic adults (paedomorphs) which retain their gills and continue to live in water are found in many populations.
These gilled adults may outnumber transformed individuals.
This salamander is nocturnal, but also active in daylight during wet conditions.
Adults are typically found within 50 meters of streams.
Terrestrial adults often remain in underground retreats, emerging to forage on the forest floor on rainy nights and during daylight in wet periods in winter.
They are sometimes seen walking on forest trails in daylight and on paved roads near streams on rainy nights, especially during the first heavy Fall rains in November and December. Adults are also found under rocks in streams and under objects on the ground that retain moisture such as rocks, logs, and artificial cover objects.
Post-metamorphs sometimes return to streams when terrestrial conditions become hot and dry.
Large adults are capable of delivering a painful bite.
Other defenses include arching the body and lashing the tail and excreting noxious skin secretions.
Diet and Feeding
Giant salamanders will consume anything that they can overpower and fit in their mouth, including a variety of invertebrates such as sowbugs, pillbugs, worms, and slugs, and small vertebrates such as small rodents, lizards, small snakes, and salamanders, including other Giant salamanders (and Northwestern Salamanders - Ambystoma gracile, which produce an alkaloid toxin - Rombough, Herpetological Review 48(1), 2017).
Eggs or embryos have been found in large larvae and terrestrial adult giant salamanders.
Giant salamanders are sit-and-wait predators. When prey comes near they lunge quickly to grab the prey with their mouth and crush it with their jaws.
Aquatic larvae feed on small aquatic invertebrates including insects and larvae, mollusks, and crayfish, and small fish hatchlings.
Reproduction is aquatic. Fertilization is internal.
Females reach sexual maturity in 5 to 6 years.
Mating occurs mostly in spring, usually in May, but later in the hear at high elevations. Breeding may also occur in the Fall.
Terrestrial males and females move from their terrestrial hiding places to a stream in which to breed..
According to Nussbaum et al, 1983, observations of Dicamptodon in captivity and in the field suggests that courtship takes place in "hidden water-filled nest chambers beneath logs and stones or in crevices.
Males deposit up to 16 spermatophores.... Females pick up one to a few of the sperm caps with their cloacas and deposit their entire clutch of 135 to 200 eggs (larger females deposit more eggs) in the nest chamber. The eggs are attached singly, side-by-side, usually on the roof of the nest chamber."
Only a few nest sites have been observed in the wild.
The female stays with the eggs to guard them until they hatch, usually in November and December, or in 6 to 7 months, during which time she does not eat.
A female probably does not breed more than once every two or more years because of the long time she spends with her eggs. "The function of maternal care is not fully understood, but prevention of egg cannibalism seems to be one function." Eggs or embryos have been found in large larvae and terrestrial adult giant salamanders which indicates that they are a theat to a nest site.
Larvae and Young
Larvae hatch in water and transform to a terrestrial form in probably about 18 - 24 months after hatching, depending on environmental conditions and the size and permanence of the stream.
Larvae live on their yolk for 3-4 months after hatching then they feed on invertebrate prey and small amphibian larvae.
Some larvae may overwinter and transform in their third year.
Young larvae are found in still water near the shoreline, often under small rocks and leaf litter.
Older larvae are found in the main stream channel.
Larvae are more abundant than transformed adults.
Larvae can be found exposed in the water at the edge of a stream at night by shining a light at the water.
Recently metamorphosed juveniles move out of streams to the surrounding habitat during wet periods.
Occurs in wet forests in or near clear, cold streams and rivers, mountain lakes, and ponds. Takes shelter under rocks, logs, in logs, and in burrows and root channels. Population densities are highest in creeks with many large stones. Larvae frequent clear cold streams, creeks, and lakes and can be found under rocks and leaf litter in slowly moving water near the banks or exposed in the water at night.
Occurs in California from Mendocino County near Point Arena, north along the coast and into the north coast mountain ranges as far east as Shasta Reservoir, Shasta County, and McCloud, Siskiyou County, and north to the Oregon border.
From there it ranges north west of the Cascade mountains (and east of the crest in a few locations) into extreme southwestern British Columbia, but is absent from the Olympic Peninsula in Washington.
Occurs from sea level to near 7,000 ft. but mostly below 3,100 ft.
The historical distribution of this slamander has probably not declined, though there certainly has been some localized extirpation from urbanization and some fragmentation within the range mostly due to forestry practices. Studies indicate a long-term decline in populations after logging of old-growth forests. D. ensatus is far more abundant in unsilted streams than in streams that have become silted due to logging or other alteration of the land above the stream. Creek sedimentation eliminates access to cover under rocks in the streambed which is critical habitat.
Pacific Giant Salamanders
Coastal Giant Salamander
(Baird and Girard, 1852)
Baird and Girard, 1852 - Proc. Acad. Nat. Sci. Philadelphia, Vol. 6, p. 174
Stebbins, Robert C., and McGinnis, Samuel M. Field Guide to Amphibians and Reptiles of California: Revised Edition (California Natural History Guides) University of California Press, 2012.
Stebbins, Robert C. California Amphibians and Reptiles. The University of California Press, 1972.
Flaxington, William C. Amphibians and Reptiles of California: Field Observations, Distribution, and Natural History. Fieldnotes Press, Anaheim, California, 2021.
Samuel M. McGinnis and Robert C. Stebbins. Peterson Field Guide to Western Reptiles & Amphibians. 4th Edition. Houghton Mifflin Harcourt Publishing Company, 2018.
Stebbins, Robert C. A Field Guide to Western Reptiles and Amphibians. 3rd Edition. Houghton Mifflin Company, 2003.
Behler, John L., and F. Wayne King. The Audubon Society Field Guide to North American Reptiles and Amphibians. Alfred A. Knopf, 1992.
Powell, Robert., Joseph T. Collins, and Errol D. Hooper Jr. A Key to Amphibians and Reptiles of the Continental United States and Canada. The University Press of Kansas, 1998.
Bartlett, R. D. & Patricia P. Bartlett. Guide and Reference to the Amphibians of Western North America (North of Mexico) and Hawaii. University Press of Florida, 2009.
Bishop, Sherman C. Handbook of Salamanders. Cornell University Press, 1943.
Lannoo, Michael (Editor). Amphibian Declines: The Conservation Status of United States Species. University of California Press, June 2005.
Petranka, James W. Salamanders of the United States and Canada. Smithsonian Institution, 1998.
Corkran, Charlotte & Chris Thoms. Amphibians of Oregon, Washington, and British Columbia. Lone Pine Publishing, 1996.
Jones, Lawrence L. C. , William P. Leonard, Deanna H. Olson, editors. Amphibians of the Pacific Northwest. Seattle Audubon Society, 2005.
Leonard et. al. Amphibians of Washington and Oregon. Seattle Audubon Society, 1993.
Nussbaum, R. A., E. D. Brodie Jr., and R. M. Storm. Amphibians and Reptiles of the Pacific Northwest. Moscow, Idaho: University Press of Idaho, 1983.
Joseph Grinnell and Charles Lewis Camp. A Distributional List of the Amphibians and Reptiles of California. University of California Publications in Zoology Vol. 17, No. 10, pp. 127-208. July 11, 1917.
The following conservation status listings for this animal are taken from the October 2021 California "Special Animals List" and the October 2021 "State and Federally Listed Endangered and Threatened Animals of California" list, both of which are produced by multiple agencies and available here: https://www.wildlife.ca.gov/Data/CNDDB/Plants-and-Animals. You can check the link to see if there are more recent lists.
If no status is listed here, the animal is not included on either list. This most likely indicates that there are no serious conservation concerns for the animal. To find out more about an animal's status you can go to the NatureServe and IUCN websites to check their rankings.
This salamander is not included on the Special Animals List, meaning there are no significant conservation concerns for it in California according to the California Department of Fish and Game.