Iberian Ribbed Newt, Pleurodeles walti

The Iberian Ribbed Newt (Pleurodeles walti), known also as the Spanish Ribbed Newt, is a newt endemic to the central and southern Iberian Peninsula and Morocco. It is known for its sharp ribs that can puncture through its sides, and as such is also called the Sharp-ribbed Newt.

This newt has tubercles running down each side. The characteristically sharp ribs can puncture through these. The ribs act as a defense mechanism causing little harm to the newt. This mechanism could be considered as a primitive and rudimentary system of inoculation, but it is completely harmless to humans. At the same time as pushing its ribs out the newt begins to secrete poison from unique glands on the body. The poison coated ribs create a highly effective stinging mechanism, injecting the toxins through the skin into the predator’s mouth. The newt’s effective immune system and collagen coated ribs mean the pierced skin regrows quickly and without infection.

While in the wild, this newt grows up to 12 inches, but rarely more than 7.9 inches while in captivity. The coloration is a dark gray on the dorsal surface and lighter gray on the ventral surface, with rust-colored small spots where the ribs can protrude. It has a flat and spade-shaped head and a long tail which is about half the length of the body. The males are more slender and normally smaller than the females. The larvae have bushy external gills and normally paler color patterns than seen in the adults.

This species is far more aquatic-dwelling than other European tailed amphibians. Although they are quite able to walk on land, they rarely leave the water, normally living in ponds, cisterns, and ancient village wells that were common in Spain and Portugal in the past. They show a preference to cool, quiet and deep waters, where they feed on insects, worms, and tadpoles.

Image Caption: The Iberian Ribbed Newt (Pleurodeles waltl) at the Steinhart Aquarium, San Francisco. Credit: Pengo/Wikipedia (CC BY-SA 2.5)