Researchers led by Guilherme Gainett from the University of Wisconsin-Madison first sequenced the genome of Phalangium opilio (technically not a spider but a close relative), thought to be among the most widespread of more than 6,000 different species of daddy long legs — also known as harvestmen — documented worldwide.
Next, the scientists used a technique called RNA interference to basically turn off, or "knock down," a pair of genes associated with leg development in hundreds of daddy long legs embryos. The result was that six of the animals' eight legs were about half the size of their normal, un-engineered counterparts.
The legs seemed to be transformed into a different kind of appendage, known as a pedipalp, which is used in handling food.
This both feels like a horrifying premise to a bad sci-fi movie … and also, kind cool. Arachnids are known for having 8 legs, and by shrinking only six of those legs, the Daddy Short Legs adapted to use the other hands as sort-of-hands. That's fascinating! And creepy, sure. But there's a lot to learn from that.
Scientists tweak daddy long legs genes to create daddy short legs [Eric Mack / CNet]
The genome of a daddy-long-legs (Opiliones) illuminates the evolution of arachnid appendages [Guilherme Gainett, Vanessa L. González, Jesús A. Ballesteros , Emily V. W. Setton , Caitlin M. Baker , Leonardo Barolo Gargiulo , Carlos E. Santibáñez-López , Jonathan A. Coddington and Prashant P. Sharma / The Royal Society of Publishing]
Image: Public Domain via Wikimedia Commons