Osteoderms are bony deposits that form within the dermis, or inner layer of skin. They provide support and protection to the underlying tissue and help to anchor the muscles and tendons to the bone. The osteoderms of reptiles are often heavily ossified, forming a protective armour around the animal. Some species of fish also have osteoderms, which help to protect their delicate scales from damage.
The term “osteoderm” comes from the Greek words “osteon” meaning “bone” and “derma” meaning “skin”. Osteoderms are found in a wide variety of animals, both vertebrates and invertebrates. Invertebrate examples include crabs, lobsters and millipedes, while vertebrate examples include crocodiles, turtles and pangolins.
The structure of an osteoderm varies depending on its location in the body and its function. For example, those located near joints tend to be thinner and more flexible than those found further away from joints. Additionally, some osteoderms have spikes or other protrusions that can provide additional defence against predators or rivals.
While they offer many benefits, there are also some disadvantages to having osteoderms. One is that they can make it difficult for an animal to regulate its body temperature as they act as insulation against heat loss. Another is that they can impede movement if they become too large or numerous (as is often seen in older individuals). Finally, if an animal sustains an injury to an area covered by its osteoderms, these structures can make it difficult for wounds to heal properly.