Newly discovered big-headed ants use spines for support

Muscles hidden in spiky growths along necks of worker ants

Pheidole drogon

A STORM OF SPINES  A newly discovered ant species, named Pheidole drogon after a dragon in Game of Thrones, sports spines that resemble a dragon wing and claw. The ants can’t fly or breathe fire, but their spines are filled with muscles, which may lend support to their giant heads.

Masako Ogasawara/OIST  

The newest and thorniest members of a diverse ant family may have extra help holding their heads high.

Found in the rainforests of Papua New Guinea, Pheidole drogon and Pheidole viserion worker ants have spines protruding from their thoraxes. For many ant species, the spiky growths are a defense against birds and other predators. But Eli Sarnat and colleagues suggest the spines might instead be a muscular support for the ants’ oversized heads, which the insects use to crush seeds. The heads “are so big that it looks like it would be difficult to walk,” says Sarnat, an entomologist at the Okinawa Institute of Science & Technology Graduate University in Japan.

Micro‒CT scans of worker ants with larger heads revealed bundles of thoracic muscle fibers within spines just behind their heads. Worker ants with smaller heads did not have muscles in their spines, the researchers report online July 27 in PLOS One. More research is needed to establish the spines’ function and understand why they evolved, Sarnat says. While buff spines may support big heads, hollow spines probably keep predators at bay, the researchers suspect.    

HEAD TO HEAD The thorny outgrowths of P. drogon worker ants with large heads (left) contain muscle fibers which may support their massive heads. The spines of worker ants with smaller heads (right), on the other hand, are practically hollow. Georg Fischer/OIST

Researchers named the ants after two fearsome dragons, Drogon and Viserion, in the popular book and TV series Game of Thrones

Cassie Martin is a deputy managing editor. She has a bachelor's degree in molecular genetics from Michigan State University and a master's degree in science journalism from Boston University.

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