In the terrestrial phase they live in moist to dry habitats under woody or leafy debris, in rock crevices, or in animal burrows.

When threatened, a newt assumes a defensive posture known as the Unken Reflex in which it holds its head up and points its tail straight out to display its brightly-colored ventral side, while at the same time secreting toxin from its skin glands.

The main native predator of the California Coast Range newt is the common garter snake (Thamnophis sirtalis), some of which have apparently developed a genetic resistance or immunity to tetrodotoxin.

During courtship the male climbs onto the back of the female, clasps her tightly, rubs his chin over her nose, flutters his tail, and strokes her cloaca, a behavior called amplexus.

They have bushy gills in younger developmental stages, balancer organs, and well-developed tails that extend forward to the shoulder area.

Ingestion of this poison by handling or eating them causes severe neurological symptoms and, in some instances, death from respiratory or cardiac failure.

They are susceptible to stress from loss and degradation of habitat, and especially in the Santa Monica Mountains from predation of eggs and larvae by introduced mosquitofish (Gambusia affinis) and crayfish (Procambarus clarkia).

Large numbers of California Coast Range newts move together in breeding season, during or after rains, often traveling across roadways and highways.

During the breeding season, some residents and local governments close roads to protect migrating newts and salamanders from becoming roadkill.