Wednesday, March 4, 2009

Some salamander. Some tail.

Ensatina eschscholtzii oregonenesis.

Ensatina is a rare case of a herp being commonly known by its generic name. What does Ensatina mean? I looked, but couldn't find the answer. The salamander in this picture, about three inches long including the tail, was found during the Quest for the Giant Salamander.

This small, lungless species (E. eschscholtzii), in its seven subspecies, ranges from southeastern Vancouver Island and the Lower Mainland of BC to northern Baja California. It occurs in most of the western half of California, minus the Central Valley. The subspecies found in BC is E. e. oregonensis.

What catch my eye as I look at the picture are the constrictions on the tail. The first constriction is supposed to be there, the second, I’m not so sure. It might be a point of fracture from which the tail tip regrew. Ensatinas autotomize their tails as a defensive tactic, usually at the basal constriction, hoping to baffle a predator with a twitching distraction as the rest of the salamander gets away.

But there’s more to their tails than this. According to Amphibiaweb,

“The dorsal surface of ensatina tails contains large, densely packed poison glands, and a sticky, milky secretion is exuded when the animal is threatened (Hubbard, 1903). Ensatinas can autotomize their tails at the constricted base, and autotomized tails bend wildly for several minutes (Stebbins, 1954b; Wake and Dresner, 1967). Beneski (1989) found that ensatina tails stick to the mouths of garter snakes, inhibiting further consumption. “

Aha. The peanut butter strategy.

And more,

“It takes about 2 yr to regenerate an autotomized tail (Stebbins, 1954b; Staub et al., 1985), and tails are rarely dropped unless conditions are life threatening (Beneski, 1989).”

But tail autotomy, if it comes to that, doesn't always work out. According to a page from Santa Rosa Junior College,

“Among the predators of Ensatina are the raccoons. Adult raccoons will eat Ensatina beginning with the head down to where the tail begins, and the tail is then discarded.”

There is something very unfair about that.


KaHolly said...

How did the raccoon become so smart, I wonder? It must be a closely guarded secret!!

Anonymous said...

Really interesting. I had no idea it took so long for the tales to grow back.

Hugh said...

KaHolly, They have to learn it. Young ones bite the tail too. I wonder how they learn that not all of the salamander tastes foul.

Wren, Thanks for the Stumble!