"It's a whole new way of looking at what's in the ocean." In this undated file photo, a large group of yellowfin tuna is shown in the waters off Vibo Valentia, Calabria, Italy. Giordano Cipriani/Getty ...

Evolution has adapted the digits of mammals for an enormous range of uses, from our opposable thumbs to the spindly digits that support bat wings to the robust bones that support the hoofs of horses.