Bizarre Newt Uses Ribs As Weapons (via BBC Earth...

Saturday, August 22, 2009

Bizarre Newt Uses Ribs As Weapons (via BBC Earth News)

When attacked, the Spanish ribbed newt pushes out its ribs until they pierce through its body, exposing a row of bones that act like poisonous barbs. The newt has to force its bones through its skin every time it is attacked, say scientists who have described the form and function of the barbs in detail. Yet this bizarre behaviour appears not to cause the newt any ill effects.

The ability of the Spanish ribbed newt to expose its rib bones was first noticed by a natural historian in 1879. But scientists have now used modern photographic and X-ray imaging techniques to reveal just how the animal does it.
And what they discovered is even more gruesome than they imagined.
When the newt becomes agitated or perceives a threat, it swings its ribs forward, increasing their angle to the spine by up to 50 degrees. As it does this, the newt keeps the rest of its body still. “The forward movement of the ribs increases the body size and stretches the skin to the point of piercing it,” says zoologist Egon Heiss of the University of Vienna in Austria. The tips of the newt’s ribs then stick outside its body, like exposed spines.

But there is more to the newt’s defence, Heiss and his Vienna-based colleagues report in the Journal of Zoology.

“When teased or attacked by a predator, [the newt] secretes a poisonous milky substance onto the body surface. The combination of the poisonous secretion and the ribs as ‘stinging’ tools is highly effective,” says Heiss. The impact on any predator can be striking, particularly if they try to bite the newt or pick it up using their mouth. Then the poison in almost injected into the thin skin within the mouth, causing severe pain or possibly death to the attacker….