Thamnophus atratus, Taricha granulosa

This may be the first photographic record demonstrating that the Thamnophis genus of gartersnakes has evolved immunity to
the newts' toxin. According to herpetologists at Utah State this relationship has previously been reported only anecdotally.

When seized by a predator, newts express the deadly tetrodotoxin (TTX) as a defensive measure. TTX is
the poison found in puffer-fish and some other marine creatures. The toxin is produced by a bacterium
that the host has first acquired immunity to and then incorporated into its defense strategy.

In this shot the toxin can be seen as a milky substance on the side of the newt's tail.