While on one of my daily nature walks I looked down and spotted one of the true beauties of the woods, a red eft (see photo). They wander around, especially after rains and are very slow-moving and unafraid. Of course there is a reason for this- they are protected by a very potent poison, tetrodotoxin. You cannot be poisoned by handling the young newt, but if you eat it your nerve cells will have some severe problems. The bright orange/red coloration of red efts, which are juvenile stages of the red-spotted newt, clearly warns potential predators to leave them alone. As the red efts mature into adults, they become more greenish-yellow (see second photo). The adults return to the water where the gilled larvae started life and spend the rest of their lives there. This "reverse" life history (embryos, gilled larvae and adults are aquatic, but juveniles are terrestrial) is in contrast to typical amphibians, where only the embryos and larvae are aquatic. While there is much about this process that is unclear, it does seem likely that such an alternation of generations between habitats is probably a means of minimizing competition for limited food resources. One strange thing is that not all populations of newts have an eft stage, perhaps due to unsuitability of land habitats or less competition for food in the water. A similar phenomenon may cause retention of gills in some populations of tiger salamanders (leading to presence of aquatic, reproductively adult axolotls that resemble gilled larvae).
Another really interesting feature of red efts is that they are probably mimicked by other amphibians such as the red salamander (see photo). This latter creature is apparently tasty but may be protected by its resemblance to the very toxic red eft. Isn't it intriguing how the color red has come to be used as both a warning and an attractant, for example as the prime color for flowers used for nectar by hummingbirds, and as the color of ripe fruits? Remember also that the recognition of the color red requires that an animal has color vision, which many mammals do not. So the target predators for this red-hued message by the efts is likely to be birds.
Here we have another example of the complex interactions that govern the lives and appearance of critters- just amazing!
Galax, VA & Englewood, FL