Frog is a deeply wronged animal. Sapophobia (defined here broadly, encompassing both toads themselves and frogs and toads) is the same as all other forms of prejudice: that mixture of ignorance with instinctive reaction, very difficult to change and highly harmful to innocent creatures.
A slightly more careful look, however, is enough to go beyond appearances. Think of the mucus that coats the skin of many species of this amphibian group, for example. The bigots will soon utter disgusted interjections or speak of the venom secreted by some of the animals as protection against predators. But the fact is that the skin of these animals houses some of the most sophisticated biochemical power plants on the planet. And, in certain species, these plants have an eminently romantic function. They are experts at producing a “love glue”, so to speak.
One of these examples has just been elucidated by researchers from the Butantan Institute, who studied the tremendous glandular complexity that hides in the skin of the so-called ball toad (dermatonotus muelleri). (I say “called” because, strictly speaking, as it belongs to the microhilidae family, the animal would be more like a frog, but popular designations are not usually very friendly to scientific rigor.)
At least in one point, anyway, the name used by the common people is right: the ball frog is really a ball, a shape that is probably an adaptation for the fossorial life (in underground burrows) in the caatinga and cerrado areas that the beast inhabits. Your skin produces copious mucus that is already known to be full of potent defense substances. So much so that those who collect specimens of the animal in nature avoid putting it in close contact with other species of amphibians, because the venom can end up killing other animals.
The Butantan team, led by biologist Carlos Jared, carried out a detailed analysis of the species’ skin glands, identifying structures specialized in the production of mucus and venom. But the group’s new study, published in the journal iScience, also revealed the presence of a third type of gland, responsible for producing a series of substances with adhesive properties. The structures only appear on the chest, on the underside of the front legs and on the “back of the hand” of males of the species.
The existence of these glands helps to elucidate a love conundrum. To mate, male and female enter the water and the partner hugs the beloved above her, placing the front paws under the partner’s armpit and fertilizing her eggs as she expels the so-called whose from the cloaca. Now imagine two viscous balls trying to stick together like this in a liquid medium. Mission nearly impossible—if it weren’t for the males’ specialized glands.
“It’s practically unfeasible to make them come off, you’d end up peeling the skin off,” Jared told this columnist. It seems like such an inconvenience, but the persistence of the glue helps the couple to complete several egg fertilization sessions, thus generating a good amount of chicks. There are indications that the glands also produce a molecule that, at the right time, dissolves the glue.
For Jared, the study could even end up having intriguing implications for medical technology. The substances produced by the glands of males could be used, for example, in surgical glues, facilitating the healing of deep cuts. It is worth remembering that biodiversity is still the main inspiration for innovative drugs around the world.
