The defence works mechanically. Under threat the newt rotates its ribs forward and outward by roughly the same angle each time, increasing the body's width and driving the rib tips through the body wall at points marked externally by the orange warts. Those warts are poison glands, so a rib emerging there is coated with secretion as it exits, delivering the toxin directly into a predator's mouth.
X-ray and histological work has shown the ribs pierce the skin without tearing muscle in a damaging way, and the punctures close afterwards. There is no evidence of infection resulting from repeated use, which has drawn interest to the animal's skin healing and immune response.
The behaviour is sometimes described as the newt shooting or detaching its ribs. It does neither: the ribs stay attached and articulated, and the display requires the predator's grip to work against. The species is otherwise unremarkable to handle, and its conservation status is declining with the loss of small water bodies in Iberia.