Dicamptodon

Nature Notes by Dr. Frank Lang

Amphibians: frogs, toads, salamanders and newts usually spend part of their lives in water, part of their lives on land. They live double lives. Many amphibians are in decline for reasons that are not totally clear. Lost or altered habitats seem likely culprits. Cool, clear streams turned crock-pot warm by poor land use or increasing ultraviolet radiation are among the possibilities. Maybe it is their parasites.

I like salamanders. Some are big, some are small, some are rough, some are smooth. A personal favorite is Dicamptodon, the Pacific giant salamander. Its range extends from southern British Columbia south along the Puget Trough through southwest Washington, western Oregon and northwest California to Santa Cruz. Like western red cedar, Dicamptodon is also found in Idaho. Its habitat? Cool, moist, coniferous forests near cold, clear streams and mountain lakes. They are big, to 13 inches long, with bulging eyes and vertically flattened tails. The terrestrial adult’s smooth moist skin is reddish-brown or chocolate brown with a marbled pattern of tan. The aquatic larval stage, equivalent to tadpoles, is generally drab brown with short bushy gills. Larvae get large as well. Both have prodigious appetites.

Years ago a former colleague brought a large adult Dicamptodon into the lab. We watched as he placed the beast in the sink and then covered the sink with boards and bricks, lest the beast try to escape. Dicamptodon is not a weakling. Next morning I got a call, “Come see Dicamptodon.” I did, and much to my amazement I saw two animals in the sink, Dicamptodon and a meadow mouse of size. This was my first realization that Pacific giant salamanders are not only big, but fierce. When agitated they may let out a sharp, low-pitched yelp. A yelp of less volume, I suspect, than that emitted by an unsuspecting human agitator when bitten by a salamander.

Dicamptodon has a powerful bite and can inflict a painful cut. Its name, Dicamptodon, refers to its two curved rows of teeth. Besides small mammals, they eat snakes, other amphibians, insects, snails, slugs and worms. My colleague, Michael Parker, is a Dicamptodon expert. He reports that Dicamptodon may occasionally dine on young steelhead and other salmonid fishes. Human fisher-folk should not be too upset by this. It is part of the environmental sieve that makes for smarter, better, wilier, wild fish. Larval diet mostly consists of aquatic and terrestrial invertebrates.

Most folks who study reptiles and amphibians think the Pacific giant salamander is primitive, most like the original inventions that left water, slime, and ooze for land. It is primitive in many ways but one. Mating Dicamptodons practice internal fertilization, but dear readers, you will, I fear, be disappointed when you learn the details. After a brief in-stream mating ritual, the male Pacific giant salamander deposits gelatinous sperm-capped structures on the stream bed. The female then picks up the sperm packets with her cloaca1 lips and deposits them within her cloaca, a common opening to her reproductive, digestive, and urinary tracts. There, inside her body, sperm unites with egg, safe from the uncertainty of external fertilization, a common practice where many lower vertebrates squirt sperm over already laid eggs. The female lays her fertilized eggs in water and attaches them to rocks and chunks of wood. She then stands guard until the larvae hatch, presumably to keep them safe from predators.

Large is relative. The giant salamander of China and Japan may measure six feet in length. According to my Harvard pals who have done extensive field work in China, anything that swims, walks, crawls, or flies is fair game for human consumption. During a slide presentation they talked of Wa-wa-u. The photograph was of a really big salamander being readied for the wok. It filled a standard wash basin. Fortunately for pups and babies it mainly subsists on fish and frogs. If you come across Dicamptodon, look, don’t touch. And be grateful it isn’t six feet long.

— Dr. Frank Lang

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