Spanish Ribbed Newt

Whenever I think about ribs I’m normally thinking about where I can find the best prime ribs for dinner or that I appreciate how they protect the important organs in my body. I consider my ribs to be pretty good at defence, especially when I accidentally walk into something or somebody. However, the simple defence that my ribs accomplish is nothing compared to how the Spanish ribbed newt (Pleurodeles waltl) uses its ribs for defence.

A) Area of high secretion B) Posture
when extending ribs (Heiss et al. 2009)

The Spanish ribbed newt has spear-shaped ribs that can be forced through its body wall when it is feeling threatened by a predator. In order to project their spines through their skin, the newt will bend its body to a maximum angle of 92°. A two-headed joint had to be developed in order for the ribs to be protruded.  The areas where the ribs penetrate are beneath lateral orange warts which provide a potential aposematic signal to predators. These areas also lack permanent pores despite penetration happening multiple times (Heiss et al. 2009).

Not only can the ribs defend against predators but their skin secretions are also toxic. When the rib tips go through the skin the secretion coats them. Therefore, if a predator attacks it won’t only be stabbed by the ribs but the poison on the skin of the newt will also harm the predator (Nowak & Edmund, 1978). If the predator attacks the newt using its mouth the poison will be injected into the mouth and will cause pain or death. Even though the skin of the newt is damaged it likely has a remarkable ability to repair skin and peptides that protect it against pathogens (Zasloff, 1987). Even though the newt harms itself in order to avoid being eaten the harm that it causes to itself doesn’t seem to hinder its ability to continue surviving.

I couldn't find a video of it using its ribs for defence so this video is just it walking around:

References:

Heiss, E, Natchev, N, Salaberger, D, Gumpenberger, M, Rabanser, A & Weisgram, J 2009, ‘Hurt yourself to hurt your enemy: new insight on the function of the bizarre antipredator mechanism in the salamandrid Pleurodeles waltl’, Journal of Zoology, vol. 280, no. 2, pp. 156-162, doi:10.1111/j.1469-7998.2009.00631.x.

Nowak, RT & Brodie, ED 1978, ‘Rib penetration and associated antipredator adaptations in the salamander Pleurodeles waltl (Salamandridae)’, Copeia, vol. 1978, no. 3, pp. 424-429, doi:10.2307/1443606.

Zasloff, M 1987, ‘Magainins, a class of antimicrobial peptides from Xenopus skin: isolation, characterization of two active forms, and partial cDNA sequence of a precursor’, Proceedings of the National Academy of Sciences of the United States of America, vol. 84, no. 15, pp. 5449-5453, < http://www.pnas.org/content/84/15/5449?tab=author-info>.