Subject: [Tweeters] Rough Skinned Newts
Date: Mar 11 21:13:27 2005
From: Don McVay - dmcvay at cmc.net


Hi Tweets,

The thread of Rough Skinned Newts, Taricha granulosa granulosa, caught
our attention.?We visited Lake 22, east of Mount Pilchuck, in the
spring, several years ago while ice was still covering most of the
lake.?Near the stream that flows out of the lake we discovered a ball
of many newts about the size of a basketball.?These newts were
preparing for their interesting mating behavior.?We captured a few of
these newts and spent a few years observing their behavior and doing
some limited research on the hormones involved in their breeding
behavior.

?We discovered that most of the newts were males.?This was determined
by their size, the lateral compressed shape of their tail, large
nuptial pads on their fore limbs, and swollen cloaca.?In the center of
the ball of male newts there was a smaller number of female newts.?The
females are smaller; tail not exaggerated, no nuptial pads and a
smaller cloaca.

?Female newts secrete a pheromone, which attract males during the
breeding season.?Experiments have been done to verify this effect by
placing female newts in breeding condition in a container with a
sponge.?The sponge is then removed and placed in an area upstream of
male newts.?The males soon travel great distances to the sponge,
attracted by the pheromones, which had been absorbed by the sponge from
the female and then released from the sponge when placed in the stream.

?Females choice determines the most fit male who amplexes the female by
grasping her with his forelimbs and rubbing her head with his mental
glands on both sides of his chin.?The secretions from the mental glands
stimulates the females to releases more pheromones which further
stimulates the male to deposits a spermatophore which the female then
picks up with her cloaca.?After a period of maturation the fertilized
eggs are then deposited on the substrate in a gelatinous mass.

?Depending on water temperature the larva hatch and mature in a few
months and then may become terrestrial for several years before
returning to aquatic environments.?Adult Rough Skinned Newts have been
known to live more than 30 years in captivity.?The newts that we
studied were returned to Lake 22 after our studies.

These newts also secrete tarichatoxin from their skin glands.?This
toxin is the third most deadly non-protein neurotoxin and is related to
tetrodotoxin found in puffer fish.?Human deaths have been recorded from
ingesting this toxin.?So be careful when handling these amphibians.

We would appreciate any updated information about the behavior of these
interesting creatures.

Don and Sandi McVay
Queen Anne, Seattle
dmcvay at cmc.net

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