A remarkable discovery has been made in India, where scientists have found a strange tadpole that loves to burrow through sand.
The bizarre creature was found in the Western Ghats in India by Gayani Senevirathne from the University of Peradeniya and his team. The mountain range is famous for its incredible biodiversity. Tadpoles do not usually burrow through sand, and even more strangely this creature was observed swallowing the material.
Indian dancing frog tadpole finally discovered
Scientists found the tadpoles deep in streambeds, where they live in utter darkness until they are fully developed. They are from the Micrixalidae or Indian Dancing frog family, and researchers confirmed that they are Micrixalus herrei in a paper published March 30 in the journal PLOS ONE.
According to study author SD Biju of the University of Delhi, India, this is the first time that tadpoles from the frog family have been seen. Previously only adult dancing frogs had been seen. “These tadpoles probably remained unnoticed all these years because of their fossorial nature, which in itself is a rare occurrence in the amphibian world,” he said.
Indian dancing frogs are usually seen sitting on boulders, waving their legs in a sexual and territorial display. However the tadpole had never been observed, the only frog or toad that scientists had never seen in its developmental stage.
Scientists find muscly tadpole under sand beds
The discovery of the tadpoles showed several adaptations to their environment. Their eyes are covered by skin to protect them from the abrasive sand, and their eel-like bodies are more muscular than your average tadpole.
The tadpoles have no teeth, but they do have well-serrated jaw sheaths. Their function is to block grains of sand from entering the mouth during feeding. However their guts were found to contain small grains of sand, as well as decaying organic material.
Scientists found that the tadpoles’ ribs have increased muscle attachment that aids their movement through sand. Prof. Madhava Meegaskumbura from University of Peradeniya states, “only four families of frogs are reported to have ribs, but we show that at least some of Micrixalidae also have ribs, even as tadpoles; this adaptation may provide for greater muscle attachment, helping them wriggle through sand.”
Western Ghats range a hotspot for biodiversity
It was also observed that the tadpoles have so-called lime sacs, white globular sacs containing calcium carbonate, which most other species of frog do not. Prior to this discovery little was known about the preferred habitat of the tadpole, but it appears that it lives in sandy banks which are sheltered by tree canopies.
It is thought that the Micrixalidae tadpoles hang on to rocks using powerful mouths in the early stages of development. Once their arms are strong enough they then burrow under the sand, where they live until they are fully developed.
The findings show the amphibian diversity of the Western Ghats mountain range. Scientists have long known the range to be a hotspot for biodiversity, and this latest discovery shows the importance of the region as a source of information for frog conservation.
Adult Indian dancing frogs are fairly normal, and the tadpole has shocked some scientists. James Hanken, a herpetologist at Harvard University who wasn’t involved in this paper, says the change from “bizarre-looking” tadpoles to adults is remarkable. “There’s nothing in the adult that would lead you to suspect the larval stage is so weird,” he says.
