All but six of the world's 1,200 known species of bats roost by hanging with their heads down and their feet up, often clinging to surfaces with their claws. But new research out of Brown University shows that a bat in Madagascar, Myzopoda aurita, uses wet adhesion to attach itself to surfaces. This bat, unlike its fellow bat-cousins, roosts head-up. And this has turned scientist’s understanding of bat behavior upside-down.
So who exactly is the elusive sucker-footed bat? Endangered, it is listed as vulnerable to extinction by the International Union for Conservation of Nature. It is a small creature about two inches long and weighing one-third of an ounce. It prefers to roost on the slick surfaces of broad, fan-like leaves located high off the ground in an indigenous tree called Travelers' Palm.
Daniel Riskin is a postdoctoral research associate in ecology and evolutionary biology at Brown University. Last summer, he traveled to Madagascar with biologist Paul Racey to study one of the two species of sucker-footed bats. Their findings are published in the Biological Journal of the Linnean Society.
The researchers started out by giving Myzopoda two kinds of surfaces to climb. One surface was covered with tiny holes and other one had tape covering its holes. The bat proved that it could climb on both, including the surface with holes, which would be impossible if it was using suction.
Instead, Riskin and Racey found that the bats use wet adhesion, secreting what is possibly sweat, to allow the pads on the bats' wrists and ankles to attach to surfaces. Next they held the bat so it's head was up and body in a vertical position. Riskin then discovered that the bats could easily "unpeel" their pads from any surface. This explained how the bats could roost head-up.
Thyroptera is a suction-footed species that lives in Central and South America and is a close cousin to Myzopoda. Riskin believes that Thyroptera is a later stage of evolution of the two bats. Myzopoda, through wet adhesion, can only roost head-up. Thyroptera, using suction, can roost either head-up or head-down. Riskin notes, "It doesn't make sense to go through suction to get to wet adhesion, but it does make sense to go through wet adhesion to get to suction."
So does this mean a name change is in store for the sticky bat? "You can't change Latin names," points out the study's lead author, "so it's stuck with it."