California Newts, Poisonous and Friendly

There are few creatures in the world who are as naturally gentle as this amphibious friend. The California newt, or Taricha torosa, lives underwater about 90% of the time in select creeks and ponds throughout coastal and central California. This species is incredibly cute, and moves slowly through the water or on land, perpetuating their gentle allure.

The main reason why these creatures are so gentle and friendly is their natural toxicity. These newts are poisonous if ingested. This quality makes it so that they do not have any natural predators, since anything that would try to eat them would die. Since eating one of these means certain death, no snakes, frogs, racoons, or any predators of other amphibians go near the newts.

You may be wondering how the predators know that these newts are toxic. The answer is what scientists call “aposematic coloration.” Aposematic coloration is essentially the opposite of camouflage. Rather than hiding from predators by blending in with the background, aposematic coloration stands out against the surrounding area and specifically makes the animal visible to predators.

Often aposematic coloration takes on bright reds, and oranges, or other bright colors. This way the predator can easily see the animal and the bright warning colors, and realize this animal is poisonous. Throughout the animal kingdom this same technique has developed. For example monarch butterflies are poisonous if eaten, and feature the same bright orange/red coloration. Interestingly, this has evolved a tricky counterpart.

Monarch featuring aposematic coloration

Painted lady butterflies have evolved to have very similar coloration to monarchs, and when flying by are almost impossible to differentiate from monarchs. However, the painted lady butterflies are not poisonous, but hope that imitating the aposematic coloration of the monarchs will fool predators! Only very discerning predators can single out which butterflies are safe to eat.

Overwintering monarchs sleeping communally

The California newts, featuring this aposematic coloration are almost never interfered with and live a calm and relaxing lifestyle. They never deal with predation in their daily lives so they can be easily observed and enjoyed by those of us lucky enough to find them while on a hike in the creek. Although these newts are able to avoid predation as adults, they do have a very unfortunate predator.

The newts reproduce like most other amphibians, and lay large egg sacs attached to stick or logs underwater. The offspring develop for a few weeks in this egg sac before hatching. Unfortunately for California newts in many streams around California their egg sacs are targeted by the invasive species of Red Swamp Crayfish. These crayfish were introduced throughout the state as a potential food source, but have rapidly taken over streams and become a serious problem.

Crayfish from Texas

Newts do still persist in areas with crayfish, however they are severely impacted as many of their eggs are consumed. Newts like other amphibians breathe through their skin by extracting oxygen from the water molecules they are submerged in. Due to this fascinating way of breathing they are highly susceptible to toxins and pollutants in the water, as they will flow right into the newts porous skin.

Because of the threat of crayfish and pollution, newts have been slowly disappearing from many of their native streams and retreating further away from highly trafficked areas. Thankfully there are still many creeks and pools in hidden areas that are free of crayfish and human byproducts. I won’t give it away here, but if you hike deep enough up the creeks in California you may just be lucky enough to find some newts. Look out for the bright aposematic coloration swimming through the water!

Let us know in the comments if you’ve seen these sweet creatures before! Let's work hard to keep our waterways clean and free of invasive species.

Newt photos by Isaac Yelchin, Monarch and Crayfish photos by Alex Havasi

Isaac Yelchin is foremost a herpetologist. He studies lizards, frogs, newts, and the like. Specifically, he spends all day and night thinking about what it is like to be an animal. What are the animals thinking about? What is their perspective? When he should be working, he sits and stares at his pet lizard asking himself these questions.