Using X-ray cameras, researchers discovered that cane toads can swallow their tongues every time they eat, something humans cannot do.
X-ray cameras captured the eating process of the cane toad. (Video: Science Alert)
A research team led by herpetologist Rachel Keeffe at the University of Florida was surprised to find that the tongue of the cane toad retracts deep into its throat as it extends its tongue to catch prey. “We knew a lot about how cane toads stretch their tongues and stick to their prey, but before this study, everything that happened after they closed their mouths was a mystery,” Keeffe shared. She and her colleagues published their findings on November 15 in the journal Organismal Biology.
The research team utilized a high-speed X-ray technique called XROMM (X-ray Reconstruction of Moving Morphology). The results left them stunned. According to Keeffe, when eating, the entire floor of the mouth is pulled back into the throat along with the cane toad’s tongue. This entire process lasts less than two seconds.
Cane Toad
For detailed analysis, the researchers spent months feeding and then observing cane toads (Rhinella marina). Their primary diet consisted of crickets. They discovered that the key component enabling cane toads to perform this action is the hyoid bone. This is a horseshoe-shaped cartilage located at the back of the throat, fixed in place by muscles. The hyoid bone closes and presses the tongue against the roof of the mouth. It then moves forward, sweeping food into the esophagus. This may explain the existence of tooth-like ridges in the throats of cane toads, which could help in scooping food.
To track the movement of the tongue, the research team attached tiny metal beads to the muscles. In the video, the orange part represents the tip of the tongue extending to catch insects and retracting into the mouth in a flash. In their paper, Keeffe and her colleagues noted that the cane toad’s tongue can retract as deep as 4.6 cm into the throat, nearly reaching their hearts.
In comparison, the average extension distance of a cane toad’s tongue to catch insects is 4 cm. Next, the research team plans to investigate other frog species to determine whether similar feeding mechanisms are common among them.
| The cane toad measures 15 cm long and has a coloration that ranges from light brown, reddish-brown, dark brown, to gray, with its body covered in warts. They have large glands on their shoulders and just behind their eyes filled with milky white toxins. Although harmless to humans, cane toads can be deadly to pets if a curious dog attempts to lick or bite them. |
