Nature News: Eastern red-spotted newts have a poisonous adolescence

Published July 14 in the Portsmouth Herald, York Weekly, Foster’s Daily, etc.

A red eft on the prowl. You can see the beautiful red spots on its back. This one was at least 1/2 mile from the nearest pond. photo by Sue Pike

One of my favorite memories is hiking up Mount Kearsarge with my dad and finding tiny red newts climbing along the trails with us.  These are the “teenage” stage of the eastern red-spotted newt, a type of salamander with a fascinating life cycle. 

Eastern newts breed and lay eggs in ponds, their olive-green colored, gill-bearing larvae hatch out and spend at least a few months in the water. After approximately 5 months  these aquatic larvae metamorphose into the terrestrial red eft stage and spend the next two to seven years roaming the woods eating a variety of insects and snails and tiny jumping springtails (I feel like they must be the popcorn of the woods).   

The bright red color of the eft is a terrific defense against predators. Those tiny bumps just visible on their backs contain tetrodotoxin, a deadly neurotoxin. Bearing this bright color is a great example of warning (or aposematic) coloration-the use of conspicuous colors or markings to scare off predators. Because the toxin is located on the back, most animals that do prey upon salamanders have learned to eat only the heads and bellies. As they become sexually mature and transform into aquatic adults, efts lose their bright colors and some of their toxicity, resorting to camouflage as their best means of avoiding predation.  However, they do retain remnants of that warning in the form of little red spots fringed with black on their back…warning that they are distasteful enough that they shouldn’t be eaten.  For this reason the adults can coexist with fish- handy since the adults live in ponds.

I tend to associate newts with witches due to that famous witches chant in Shakespeare’s Macbeth  “Eye of newt and toe of frog, Wool of bat and tongue of dog, Adder’s fork and blind-worm’s sting, Lizard’s leg and owlet’s wing, For a charm of powerful trouble, Like a hell-broth boil and bubble.”  Sad for the newt but definitely a powerful image.  Luckily for the newt most of the ingredients in that witch’s cauldron were actually terms for herbs used in potions: eye of newt was another name for mustard seeds, toe of frog was buttercup and wool of bat meant holly leaves.

One rather magical thing about newts is their ability to regenerate body parts–not just tails or limbs, but organs and tissues like heart muscle, parts of their nervous systems, even the lens of their eyes!  Because of this they have long been studied in the hopes that if we can uncover how they are capable of such extreme regenerative feats we can apply this understanding in human regenerative medicine.  

It had been hoped that the red spotted newts’ regenerative ability relies on a basic genetic program common to all animals.  Instead of sequencing the entire newt genome (it is huge, ten times larger than our own!), researchers have looked at RNA transcripts in both normal and regenerated tissues to try to understand when, in evolutionary history, the newts’ regenerative ability arose.  Ideally this ability would be present in ancient ancestors, making it more likely that we might carry the seeds of regenerative ability in our own genes, wouldn’t it be neat if we could flip a genetic switch and regrow a lost limb!  Unfortunately, the results of these studies suggested that this regenerative ability arose relatively recently, so the chances for that kind of switch are very low.

A red eft along the trail at Blue Job

Just the other day I was hiking up Blue Job Mountain in Farmington, New Hampshire. It was extremely humid and foggy, perfect weather for a newt – and there, along the trail, this tiny bright splash of red materialized out of the mist.  Like a salamander (newts are a type of salamander) their skin needs to be kept moist, so you are most likely to see them  out and about on rainy days.  If you happen to be on Blue Job Mountain (or any wooded area with a pond in the vicinity) sometime in the future, look for them along the trails.  Take time to pause at the end of the pond near the top and look for their parents in the shallows.  You’ll see them if you are patient: hanging motionless in the water or gliding along the bottom hunting for prey: small molluscs and crustaceans, insects, snails and other amphibians.