Turtles have shells that they can hide inside of when they feel like they’re in danger or when they are feeling anti-social and want everything around them to disappear.
On the other hand, do turtles really only have shells for protection from predators alone? Despite the long-standing idea that turtles have shells for protection, a new study published in the journal Current Biology suggests that turtles might actually have shells for something completely different.
The protection theory makes a lot of sense because turtles are relatively slow and they needed protection from much faster predators. On the other hand, if the shell was such a successful protector from predators, wouldn’t more types of animals have them?
The wide-base of a turtle shell, combined with the smooth bottom and rough edges, may have made the turtle’s shell an excellent body-sized burrowing tool. It could be utilized in such a way that the turtle could easily bottom itself out in sand and other loosely-packed Earth.
“Why the turtle shell evolved is a very Dr. Seuss-like question and the answer seems pretty obvious – it was for protection,” said Dr. Lyson, lead author of the study. “But just like the bird feather did not initially evolve for flight, the earliest beginnings of the turtle shell was not for protection but rather for digging underground to escape the harsh South African environment where these early proto turtles lived.”
Although many modern turtle species have full-body shells, which undoubtedly protect the creature from various attacks, many early turtles may have had only partial shells, such as only spanning the belly, and not the back.
Research had also indicated that turtle shell structures evolved over time from the broadening of rib bones that, over time, merged into a single unit. Such evidence was also present in the turtles that only had belly-based shells and no protection for the back.
So are turtle shells really for protection? Today they might be, but back in the early days of turtle evolution, the shell was probably just for making burrowing and digging easier on the animal, a skill that turtles still use today.
Source: Denver Museum of Nature and Science via The Atlantic