Taricha granulosa

Form and Function                             


    Adult Rough-skinned Newts are usually between 6.4 cm and 8.9 cm from snout to vent or anus which is located just before the tail, and roughly 8.9cm to 20cm in total length (California Herps 2013).


    The Rough-skinned Newt is known to come in a few variations of color being; black, brown, reddish-brown, or a light brown on the top side of the newt, with a yellow or orange underbelly. An example of these colors for a Rough-skinned Newt can be seen in the baby newt picture on the right side of the screen. The newt has a dry and granular skin with no Costal groves or ridges between the ribs (California Herps 2013). The newt has dark eyelids and yellow irises. Populations have been known to have dark splotches on their backs.  When males are breeding they develop a smoother lighter skin, a flattened tail used to aid in swimming, and rough pads on the undersides of the feet to aid in grasping females due to the fact mating is done underwater (California Herps 2013).
Close up anterior view of a baby Rough-skinned Newt. Used with permission by Stephen Hart.
Adaptations to environment

    The Rough-skinned Newt becomes aquatic when preparing to breed or undergoing breeding. Some populations have been known to become nocturnal, and others primarily aquatic as opposed to terrestrial which is the norm for the Rough-skinned Newt. During fall in most terrestrial populations, rain-fall will trigger the newt to begin wandering forage (California Herps 2013).

    The Rough-skinned Newt as evolved a defense mechanism utilizing both poison and bright colors. When in danger the newt curls its head and tail back towards each other. Doing so reveals its bright orange underbelly warning predators that the newt is poisonous and should not be eaten. During this time the newt also begins excreting toxins onto the surface of its own skin (California Herps 2013). The poison within the newt is known as a tetrodotoxin, this is a neurotoxin that will cause death in most animals, and this includes humans. The toxin can be dangerous through consumption, ingestion through a mucous membrane, or even through a cut. This toxin is so potent, it could kill as many as 25,000 mice from just one newt. However the toxin is not enough to completely protect the newt from predation, the garter snake is very resistant to this toxin and preys upon the Rough-skinned Newt (California Herps 2013).


     The newt is amphibious; therefore it has the ability to move both on land and within water. The Rough-skinned Newt has two sets of legs, with four digits on front legs, and five digits on hind legs.

Reproductive adaptations

      Males develop a smoother lighter colored skin, swollen cloacal lips, and special padding on feet used to grip females during a mating session. (California Herps 2013). Females do in fact develop a smoother skin also but not nearly as dramatic of a change as the male undergoes. Reproduction is aquatic, the adult Rough-skinned Newt breeds along the edges of slow streams, lakes, or ponds in vegetated areas. After mating has completed and the eggs are fertilized, the female attaches the eggs to shallow submerged sticks, branches, and leaves. The eggs are in fact also protected by the same chemical toxin that protects the newts from predators (California Herps 2013).

      In the event that a male Rough-skinned Newt undergoes a high amount of stress, courtship incidences decrease within the individual. A study preformed comparing the correlation of plasma corticosterone concentrations and mating incidences. The study found that under high stress the male newt will release corticosterone into its bloodstream, and the higher the concentration of this hormone the less likely a mating incidence will occur with that male (Moore and Miller 1984).

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