Putting a twist on the old saying, ‘two heads are better than one,’ how about multiple heads? New heads, old heads, even heads that can be used to take a swing at your enemy. Or, at least that’s the idea behind a species of caterpillar known as Urba Lugens.
Better known as the gum-leaf skeletonizer or the Mad Hatterpillar, this caterpillar uses its unused old heads as an ever-growing appendage that can be used to fend off predators or enemies that try to attack it.
An extensive research project was conducted on the species by the University of Sydney’s Petah Low, whose research is documented in PeerJ.
Among the examples showing that the stack of heads is used for self-defense, was a recorded instance where the caterpillar used the stack to take a swat at a pentatomid bug and even to use it as a false foe distraction.
On the other hand, Low explains that the extra heads are effective against certain predators, but not all, “While providing some level of protection, head capsules may not be equally effective against all predators and are not sufficient to prevent predation by highly motivated predators.”
So where does this stack of heads actually come from? – The species will actually shed a layer every time it molts its shell, but as it does so, the part of the shell that would once encapsulate the head remains on the body, and continues to grow with each molt, as National Geographic explains.
The real head remains at the bottom of the stack of false heads, and predators often have a difficult time finding the real head as they’re trying to attack the caterpillar.
Even if parts of the shell break off during combat, if they’re able to get away, they’ll just continue to grow more to fend off future predators that try to cause harm.
It would seem that the old wive's tail that two heads are better than one, would be right!
Source: National Geographic