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Why Does a Crocodile Have a Rough Back?

According to the U.S. Agency for International Development, crocodile skin is the costliest and most fashionable leather in Western markets. Crocodile skin is so precious, in part because only the skin on a crocodile's belly can be used for leather. Thousands of small calcium deposits called osteoderms underlay the skin on a crocodile's back, and cause the skin to be riddled with pockmarks once removed. While these bumps may inconvenience crocodile farmers hoping to make money, they are necessary for a crocodile's survival in the wild.

Osteoderms
- Crocodiles are covered with networks of interconnected scales called scutes. These scutes vary in shape and size, from the small, smooth scales found on a crocodile's neck and belly to the raised, rough scales found on the animal's back. The raised scutes on a crocodile's back contain deposits of calcium called osteoderms. Osteoderms are discreet, isolated pieces of bone. Every crocodile has a unique pattern of osteoderms, and some species have more than others. The spiked scutes along a crocodile's tail are hard, but they do not contain any osteoderms.
Protection
- The osteoderms on a crocodile's back serve as a coat of armor. These hard pieces of bone protect the crocodile from all sorts of attacks, including bites from other crocodiles. It is common to find bite marks and even other crocodile's teeth lodged into an adult crocodile's back. These hard pieces of bone function a bit like chain mail. Because each piece is independent, one piece can crack or break without causing the crocodile too much stress. Because osteoderms are small, they heal much more quickly than a large broken bone would.
Camouflage
- A crocodile's rough, irregular back also acts as camouflage and helps it to blend into natural habitats such as river banks. The bumps and discolorations you can find on a crocodile help it to resemble the rocky dirt that crocodiles like to sleep on. Crocodiles sleep on dry land and are especially prone to attack when asleep. Their rough, rocky backs help them to conceal themselves as they rest. A crocodile's rough texture also makes it easier for the animal to stealthily sneak up on potential prey.
Temperature Regulation
- Crocodiles are cold-blooded creatures incapable of regulating their own body temperatures. They need to maintain certain temperatures to survive, though. When a crocodile gets hot, it needs to cool down by slipping into some water. If a crocodile gets too cold, though, it needs to bask in the sun. The osteoderms in a crocodile's back increase the animal's blood flow to the area, and help to rapidly transmit heat from a crocodile's back into the rest of its body.

Animals & Science