No Nonsense Newts: Spanish Ribbed Newts have a Hardcore Adaption for Survival

Amphibians. These critters are soft-bodied, most are relatively small, and they can be found in just about every ecosystem. Therefore they make up a crucial part of our earth’s food webs. Despite this, these animals have fascinating methods to avoid becoming a meal. The Spanish Ribbed Newt (Pleurodeles walt), in particular, has adapted to become one of the most unappealing meals on the planet.

At first glance, this grey and dark-spotted (sometimes yellow to orange) newt (Figure 1) appears unalarming. They populate the still waters of Spain, Portugal, and Morocco opting to hide under rocks rather than fight. When they’re in danger, though, that is a different story.

These animals, that only get to about 12in (30.48cm) long, are both venomous and poisonous! The difference between these two qualities makes this species of newt all the more interesting. To be venomous, a creature must bite or sting you in order to inject toxins. For example, venom from a rattlesnake can do a number on you if you get bitten by one, though this is unlikely. Whereas being poisonous, an animal must be eaten in order for their toxins to harm you. The cane toad, for example, is a common poisonous amphibian with large poison glands that can be unfortunately harmful to curious household pets.

So how is this rather non-threatening, rock-dweller so lethal? Well, for one thing, they have large poison glands along each side of their bodies. Figure 2 shows how when threatened, these glands will secrete a toxic substance. A recent study looked into how these newts get the most out of their glands. These newts have been known to pierce their ribs through their toxin-secreting glands, coating them, in order to sting predators in defense.

This study argues that this is not a passive mechanism, but active. X-rays show a non-threatened newt with their ribs arranged as any other vertebrates’ (Figure 3, left). But when a threat is perceived, the newt flings their sharp ribs forward (Figure 3, right). Their ribs have joints (Figure 4) similar to that of our knee, allowing them to manipulate their ribs at will.

The newt will stretch its body, appearing bigger, as it punctures through its skin (Figure 5). After transforming into an unappetizing spike ball covered in toxins, the newt is lethal enough to kill small mammals. Their own poison does not appear to have any impact on the animal. Not only that, but they are able to regenerate skin over the puncture!

Even with this hard-core adaptation, the species is listed as “Near Threatened” by IUCN Red List. Habitat loss, invasive species, and pollution are among the numerous threats these newts, and the entire amphibian population, face. Educating ourselves about these critters and their challenges is how conservation starts—understanding how you can become a responsible and sustainable citizen of the earth is how we can conquer it.

(All images within the article are courtesy of Egon Heiss)