Taricha granulosa

Interesting Facts About the Rough-skinned Newt

Interesting Reproductive Features and Adaptations

    In reproduction the Rough-skinned Newt or Tarica granulosa undergoes a very unique reproductive “ritual.” The ritual begins with females gathering in a small body of water such as a pond, shortly after a much larger number of males frantically enter the water in search of a female. Many males will group around one female essentially wrestling with one another over mating for the female until finally the female chooses one male (California Herps 2013). Prior to the rough skinned newt “orgy” the Male newt develops a smother skin, and swollen cloaclal lips, he also develops padding on his feet and digits in order to assist in gripping the female during reproduction (California Herps 2013). Females undergo very slight changes in their appearance in comparison to males; the female develops only a slightly smoother skin. All reproduction is undergone in an aquatic environment. Interestingly the same tetrodotoxin or for short TTX, is found within the adult Rough-skinned Newt is also present in the eggs produced by Taricha granulosa (California Herps 2013). Taricha granulosa tends to breed and lay eggs in shallow streams and ponds, near the edge of the body of water, and close to vegetation (California Herps 2013). This is presumed to deal with the dangers of rough waters to prevent the eggs from tumbling down a fast moving river, and also to breed close to the location where eggs would be placed. The eggs are quite often attached to sticks, or vegetation as an anchor to prevent them from free-floating (California Herps 2013). An interesting behavioral adaptation relating to the reproductive behaviors of the Rough-skinned Newt was noted that the male newt will actually inhibit sexual drive when placed under enough stress by predators and other factors (Moore, Miller, 1984).

Interesting Defensive Mechanism

    Interestingly the Rough-skinned Newt becomes almost entirely aquatic when preparing to breed or undergoing breeding. One might find it intriguing that separate populations of Taricha granulosa exhibit very different life styles, in certain areas 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 fVentral view of a Rough-skinned newt laying in the moss. A bright underbelly, which signifies toxicity can be seen. Used with permission by Stephen Hart.orage (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 teal back towards each other. What this does is warn 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 or TTX, this is a neurotoxin that will cause death in most animals, and including 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). Oddly enough some research suggests that juvenile Rough-skinned Newts possess very little amounts of TTX compared to an adult Rough-skinned Newt and that larval stages actually do not contain TTX or very small amounts of TTX (Gall, B.G, et. al 2011).

Interesting Lifestyle Choices

    Populations of newts have been known to become aquatic for months, even years at a time; this is very uncommon for most newts (California Herps 2013). Finding a newt in the water is nothing unusual, like finding a newt wandering the land. However observing a newt spend its entire life, or a huge portion of its life only in the water is commonly found to be rather unusual in amphibians as a whole. Amphibians may spend a large amount of time in the water but most do not only spend large sums of time only as an aquatic animal. It is known that populations very from location to location that some exhibit more nocturnal lifestyles, some exhibit completely aquatic, and others mostly terrestrial (California Herps 2013).

Why did I choose this organism?

My group and I chose this organism for a combination of several factors. But the most prevalent reasons were access to research already done on the organism, and the other being an overwhelming interest in a poisonous skinned newt that gets in on orgies underwater. While also finding it to be an odd organism for several reasons such as the orgy and that an organism will intentionally make itself extremely vulnerable as a defense mechanism.

What is interesting about its relatives?

What I find extremely interesting about salamanders is the convergent evolution with that of lizards in terms of body shape and movement on land, and in some cases in water. I’ve always found lizards to be quite interesting so why not look at newts and salamanders for a change.

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