Catfish in India looked more like an alien than an earthbound animal. One species of the animal was studied in detail for the first time.

This fish is full of teeth, and looks highly-menacing when viewed up close. The lower jaw bulges out, much like a bulldog. The rest of the face is angular and bony, giving the species an unusual structure. However, this is a relatively small animal, incapable of great damage.

Kryptoglanis shajii lives underground, in the Western Ghats mountain range, located in Kerala, India. There, members of the species occasionally rise up from their subterranean habitat to make appearances in wells, springs and rice fields.

Biologists trying to classify this species have been challenged by its rare appearance. It was not until 2011 that this alien-faced fish was recognized as a unique species. Latest study of the bizarre species is the first-ever detailed description of the bone structure of the animals. 

John Lundberg of Drexel University, one of the world's foremost experts on catfish, led the investigation. 

"The more we looked at the skeleton, the stranger it got. The characteristics of this animal are just so different that we have a hard time fitting it into the family tree of catfishes," Lundberg said.

From the outside, this species does not look particularly unusual for catfish. The differences (and the alien-like toothy grin) are revealed in CAT scans and other techniques, allowing researchers to view under the flesh of the animal. 

These unusual bone structures make it difficult to place Kryptoglanis among other species. Even DNA evidence is inconclusive about possible relations to other species. 

Lundberg added that "Kryptoglanis most likely eats meat, in the form of small invertebrates and insect larvae - whatever might be found in the groundwater and could be captured by the fish, which at less than ten centimeters is smaller than an adult human's pinkie finger. The fish can move swiftly in its environment, as evidenced by video footage of collected fish darting through water to grab food."

Ralf Britz at the Natural History Museum of London also conducted an independent analysis of the fish, using a method called clearing and staining. In this process, chemicals are used to make the flesh of the fish transparent, and dyes are used to highlight structures. 

A video showing mapping of the bony structure of the animal is posted on the YouTube page for the Academy of Natural Sciences. 

Study of the unusual fish was detailed in the journal Proceedings of the Academy of Natural Sciences of Philadelphia.