Newt
Newts, as with salamanders in general and other amphibians, serve as bioindicators because of their thin, sensitive skin and evidence of their presence (or absence) can serve as an indicator of the health of the environment. Most species are highly sensitive to subtle changes in the pH level of the streams and lakes where they live. Because their skin is permeable to water, they absorb oxygen and other substances they need through their skin. Scientists study the stability of the amphibian population when studying the water quality of a particular body of water.
STS-65
At least two of the four adult newts died on the voyage. The first newt death was attributed simply to stress. The second dead newt was found by Donald A. Thomas late on Sunday 17 July 1994 while checking the tanks, however the second death was called "peculiar" in a comment by Dr. Michael Wiederhold, a scientist on the ground. At the time it was said it would be difficult to remove the newt from the tank because of weightlessness, but the dead animal could contaminate the tank if left inside. The newts were Japanese Red-bellied Newts ("Cynops pyrrhogaster").
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