California giant salamander
| California giant salamander | |
|---|---|
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| Scientific classification Edit this classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Amphibia |
| Order: | Urodela |
| Family: | Ambystomatidae |
| Genus: | Dicamptodon |
| Species: | D. ensatus
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| Binomial name | |
| Dicamptodon ensatus (Eschscholtz, 1833)
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| File:California Giant Salamander (Dicamptodon ensatus), Range Map.svg | |
| IUCN range map for D. ensatus, Version 2022-2 | |
| Synonyms[1] | |
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The California giant salamander (Dicamptodon ensatus) is a species of salamander in the family Ambystomatidae. D. ensatus is endemic to California, in the western United States. Terrestrial adults spend most of their time on land in close proximity to fresh water. In contrast, during breeding, in larval development, and neoteny they spend their time inside shallow fresh water. The species once additionally included individuals now belonging to the species D. aterrimus (Idaho giant salamander) and D. tenebrosus (coastal giant salamander), under the common name Pacific giant salamander, which now refers to the whole genus.
Taxonomy
[edit | edit source]The Pacific giant salamander (D. ensatus) was thought to consist of three geographic populations: an Idaho group, a group in northern California, and a group in Oregon and Washington.[2] In 1989 genetic studies showed that the D. ensatus populations consisted of three species: the Idaho giant salamander (D. aterrimus) in Idaho, and two highly divergent species with a narrow hybrid zone in California, the coastal giant salamander (D. tenebrosus) (ranging from northern California to Washington) and the California giant salamander (D. ensatus) (ranging from Santa Cruz County to Mendocino County).[3][4] A fourth species of Dicamptodon, Cope's giant salamander (D. copei), lives on the Olympic Peninsula, Washington.
Distribution and habitat
[edit | edit source]Geographic range
[edit | edit source]The California giant salamander is endemic to Northern California and lives up to 6,500 feet (2,000 m) primarily in damp, coastal forests including coast Douglas fir (Pseudotsuga menziesii var. menziesii) and California coast redwood (Sequoia sempervirens) in both montane and valley-foothill riparian habitats. They tend to be common where 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.[5]
It is found in two (possibly three) isolated regions. The first range includes Sonoma, Napa, and Marin Counties, southwestern Lake County, western Glenn County, and southern Mendocino County. The other documented region is south of the San Francisco Bay from central San Mateo County to southern Santa Cruz County plus western Santa Clara County. The California giant salamander does not occur in the East Bay, forming a gap between these two populations.[4][6] There is an unconfirmed sight record from Big Sur in Monterey County, approximately 75 miles (100 km) to the south of the documented population in the Santa Cruz area.[4]
Habitat preference
[edit | edit source]The natural habitats of D. ensatus are damp temperate forests and clear, cold freshwater streams, ponds, and lakes.[1]
Commonly found near hiding spaces like large rocks or wood, within close proximity to leafed debris, small shallow forms of water, and moist soil near banks.[7]
Studies have found the California giant salamander to be a good indicator species for the health of headwater streams.[8]
Adult salamanders were found near deteriorating waterway infrastructure, however more research is needed to be determine if this is a preferred habitat.[9]
Description
[edit | edit source]The adult California giant salamander can reach 17–30.5 cm (6.7–12.0 in) in total length (including tail).[10]
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.[10]
Behavior and ecology
[edit | edit source]Activity
[edit | edit source]The California giant salamander is predominantly nocturnal.[4]
diurnal activity can occur after the first rains following dry spells, in maintained rain, and during mating season when within 150 to 200 ft (46 to 61 m) of a water source.[4]
Diet
[edit | edit source]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), shrews, possibly reptiles, and other amphibians (including reports of smaller D. ensatus) under surface objects and in tunnels.[11] Aquatic adults and larvae eat aquatic invertebrates, fish, snakes, and other amphibians.[7]
Predators
[edit | edit source]The California giant salamander is preyed upon by the American water shrew (Sorex palustris) and the Sierra garter snake (Thamnophis couchi).[5]
Reproduction and development
[edit | edit source]Breeding
[edit | edit source]The California giant salamander breeds from March to May, with egg-laying peaking in May.[5]
Some occurrences of breeding in autumn have been reported. Both seasons have extremely maintained wet conditions, which are important for sexually mature adults. Terrestrial adults will migrate out from under rocks and logs to find puddles and streams to find mates.[4]
Reproduction
[edit | edit source]Reproduction of California giant salamanders are observed to be in aquatic environments like small puddles and fresh water streams. Mothers will guard their egg clutch for months until they hatch, to protect from predation.[2][4]
Egg deposition
[edit | edit source]Fresh California giant salamander eggs are white and are smaller than 6.4 mm (0.25 in).[7]
Eggs are concealed several feet below the surface in cold, slowly flowing water often beneath rocks and coarse woody debris in stream bottoms.[5]
Larval stage
[edit | edit source]
Once hatched in water, the larval stage of the life cycle begins where California giant salamanders grow approximately half an inch per month in the best conditions.[7][4] Larvae typically 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.[5]
Neotenes
[edit | edit source]Some California giant salamander larvae exhibit neoteny, continuing to grow into adults and become sexually mature without losing their external gills. Adult-sized neotenes have a uniform brown coloring on their heads, sides, and backs with retained external gills which allow them to live in perennial streams as aquatic adults.[5]
Diseases and threats
[edit | edit source]Disease has been known to lead to significant mortalities of the California giant salamander. In 2021, California Department of Fish and Wildlife observed poor body conditions and skin lesions on individuals at multiple sites due to parasitic infections.[12]
References
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- ^ Fong, Darren, and Howell, J.A., 2006, Distribution and abundance of California giant salamander (Dicamptodon ensatus) and signal crayfish (Pacifastacus leniusculus) in the Upper Redwood Creek Watershed, Marin County, California: U.S. Geological Survey Open-File Report 2006–1066, 45 p.
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- ^ Miller, Jaimie L., et al. "Morbidity in California Giant Salamander (Dicamptodon ensatus Eschscholtz, 1833) Caused by Euryhelmis Sp. Poche, 1926 (Trematoda: Heterophyiidae)." International Journal for Parasitology: Parasites and Wildlife 23 (2024): 100908. Web.
Further reading
[edit | edit source]- Stebbins RC (2003). A Field Guide to Western Reptiles and Amphibians, Third Edition. The Peterson Field Guide Series ®. Boston and New York: Houghton Mifflin Company. xiii + 533 pp., 56 color plates. Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).. (Dicamptodon ensatus, p. 158 + Plate 3 + Map 1).
- McAlpine-Bellis, E et al. “An Assessment of Aquatic Amphibian Biodiversity on the California Lost Coast.” Journal of freshwater ecology 37.1 (2022): 481–494. Web. https://doi.org/10.1080/02705060.2022.2118181
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