Limbless Amphibians Found to Use Slime to Dodge Predators

A limbless amphibian, known as Caecilian, Siphonops annulatus, widely distributed in Brazil. Scientists believe skin gland concentrations adapted to different evolutionary pressures in the head and posterior regions of the amphibian. (Carlos Jared/Butantan Institute)

(CN) – A group of serpent-like amphibians has developed tightly packed glands that enable them to burrow rapidly and hide from predators, according to a new report.

In the study, published Friday in the journal Scientific Reports, researchers examine the unique evolution of caecilians, which feature enlarged glands at each end of their body. The creatures are related to frogs and salamanders and favor the tropical climates of Asia, Africa and the Americas.

While both ends of the caecilians have poison glands, only one side produces poison. The new findings show skin glands on the caecilians’ top end is actually packed with mucous, enabling the creatures to burrow quickly and evade predators.

Led by Edmund “Butch” Brodie, Jr., the team focused on Siphonops annulatus, a caecilian species found throughout Brazil.

“My Brazilian colleagues noticed the burrows made by this species were lined with a shiny, slick substance,” said Brodie, an ecologist at Utah State University. “We didn’t think it was a secretion from the poison glands, so we decided to investigate.”

Roughly 18 inches in length and grayish in color, the Brazilian caecilian is a surprisingly adept burrower, according to Brodie.

“When caecilians burrow, they force their snouts into the ground and essentially dive into the soil,” he said.

Magnified image of connective tissue matrix forming honeycomb structure surrounding glands on the head of Caecilian, Siphonops annulatus. (Carlos Jared/Butantan Institute)

The team found the skin glands in the creatures’ head region, greatly enlarged and tightly packed with mucous, is unique among amphibians.

“We know of no other amphibian with this high concentration of mucous glands,” said Brodie. “In other terrestrial amphibians, mucous is mainly related to the uptake of oxygen. Here, in caecilians, it’s obviously used in locomotion.”

Further analysis of the caecilians revealed that the mucous glands extend throughout the creature’s body, gradually reducing in concentration before giving way to poison glands concentrated in the tail.

“The poison glands, resulting from a different selective pressure, provide another defense from predators,” said Brodie. “In addition to chemical defense, the tail acts as a ‘plug,’ blocking the tunnel and further deterring predators.”

The peculiar amphibian is “really a box of surprises,” the team writes.

The research was funded by the Brazilian National Council for Scientific and Technological Development.


%d bloggers like this: