While some individuals overwinter in the pond, most rough-skinned newts (
Taricha granulosa) migrate into the main pond at McLane Creek in the spring. As the males migrate into the pond, their tails flatten laterally to facilitate swimming, they develop swollen vents, their rough skin becomes smoother, and their toe pads become cornified for holding onto females.
Like many other amphibians, the skin of these newts absorbs dissolved oxygen and releases carbon dioxide when underwater. But they will also surface periodically to inhale air that fills their lungs. Birds and mammals use negative pressure ventilation; air is drawn into the lungs by subambient (“negative”) pressure generated by expansion of the thoracic volume. Newts and other air-breathing amphibians (and like air-breathing fishes) use positive-pressure ventilation to force air into their lungs. As the newt rises to the surface, the animal relaxes the sphincter between the lungs and its throat. The water pressure drives the old air out of the lungs and out of the mouth. The newt then takes a mouthful of air. With its mouth closed, it compresses the mouth cavity and this positive pressure drives the air in the mouth into the lungs.

The eggs, larvae, and adults of
Taricha newts are toxic. Skin glands synthesize an anti-predator chemical called tetrodotoxin which blocks voltage-gated sodium channels that are critical to for muscle and nerve function. The newts are resistant to their own tetradotoxin. Some populations of garter snakes have evolved partially resistant to this toxin and can eat the newts, especially those with lower levels of tetrodotoxin. This has led to an evolutionary arms race between the newts and the predatory snakes.
Steve