2016’s Halloween brought us a new holiday character that was more confusing than terrifying. We’re talking about David S. Pumpkins, and we still have so many questions. Along with his skeleton sidekicks, he made dressing up as a pumpkin with a curly wig and double-holstered guns one of the best Halloween costumes that year.
The Pumpkin Toad, however, has been dressing as a pumpkin since long before recorded history. These neon orange frogs are the world’s smallest and cutest jack-o’-lantern. They are also possibly the worst jumpers in the world. When frightened – whether of an undead bride or a natural predator – Pumpkin Toads leap into the air before making a totally uncontrolled crash landing.
Jumping is sort of a key characteristic of frogs, so it’s unusual for them to be so terrible. That’s why Richard Essner Jr. of the Department of Biological Sciences at Southern Illinois University, and his colleagues, took an interest in them and sought to understand why they are such awful acrobats. Their findings were published in the journal Scientists progress.
“I’ve been working on jumps for a long time and finally started thinking about landing behavior. I was interested in trying to find something, a group that might have ancestral behavior and morphology that would allow me to get a better idea of what the jump looked like when it first appeared,” said Essner Jr. told SYFY WIRE.
The search led him to a group of tailed frogs in the Pacific Northwest of the United States and their closest relatives in New Zealand. They separated from the rest of the frogs about 200 million years ago and could jump but could not control landing. Scientists have pinned tailed frog behavior on an evolutionary holdover from a time after powered jumping evolved, but before frogs figured out how to stick landing. Next, Essner Jr. took a look at the Pumpkin Toad, a miniature frog from Brazil.
“It was really similar to what I had seen in tailed frogs and New Zealand frogs, and it didn’t make much sense. These little frogs are part of the larger group of frogs that jump really well. So we were trying to figure out why their landing behaviors are so similar,” said Essner Jr.
When Pumpkin Toads jump in the air, they often flip or turn around (you can see them in action here). They land on their backs about a third of the time, and usually with their legs fully extended. In comparison, most frogs jump with precision and land with their legs tucked under them so they can jump again if they need to. The researchers had the idea that it might have something to do with their small size and how they impede a structure in the ear known as the semicircular canal.
“Being able to detect angular acceleration requires the movement of a fluid contained in the semicircular canals. The smaller this conduit, the greater the proportional resistance you get. Relatively speaking, there is more fluid coming into contact with the walls of the conduit, which impedes its flow,” Essner Jr. said.
Basically, as soon as they break contact with the ground, pumpkin toads lose all sense of their orientation in space and begin to spin until gravity pulls them back down. Therefore, they do not jump very often. During laboratory observations, scientists found that they only really jump when they felt threatened and wanted to quickly but clumsily escape. Fortunately, their small size – some of them barely larger than a housefly – is also an advantage, at least when it comes to crash landings.
“When you’re very young, you don’t really have problems with bone fractures, but they may damage soft tissue or perforate. One of the interesting things about this group is that “They have extra bones. They have bony plates in their backs and extra bones in their skulls. This can help protect them from injury or predation,” Essner Jr. said.
Their coloring also helps. This is a warning to predators that they are poisonous and best left alone. When you’re very small and very clumsy, you take all the help you can get. This is certainly the case for pumpkin toads, in the world of frogs they do their own thing.