Antlers are remarkable structures found on members of the deer family, known as cervids. These bony growths extend from an animal’s skull, showcasing a unique annual cycle of growth and shedding. Unlike other permanent head ornaments, antlers are a temporary display, regrowing each year. Their presence is a defining characteristic for many deer species, serving various functions.
The Building Blocks of Antlers
Antlers are composed of true bone. The primary mineral component of hardened antlers is calcium phosphate, which provides their rigidity. A substantial protein matrix, predominantly collagen, interweaves with these minerals, contributing to the antler’s overall structure and strength. Other minerals are also present, supporting rapid bone growth. The composition can vary based on species, diet, and stage of growth.
How Antlers Grow and Shed
Antler growth begins from pedicles on the skull, typically in late spring. During this rapid growth phase, antlers are covered by a highly vascularized skin known as velvet, which supplies essential nutrients for bone development. Antlers are the fastest growing bone tissue in the animal kingdom. Increasing daylight hours trigger hormonal changes, particularly increased testosterone, which regulates this growth. As summer progresses, the antlers harden, and the velvet dries and sheds, often accelerated by rubbing against vegetation.
After the breeding season concludes, a decrease in testosterone levels triggers the shedding process. A specialized layer of tissue, known as the abscission layer, forms between the antler and the pedicle. This layer de-mineralizes the bone, weakening the connection until the antler detaches. The pedicle then heals, preparing for the growth of a new set in the upcoming spring.
Antlers Versus Horns
Antlers and horns possess distinct biological differences. Antlers are solid bone structures that are shed and regrown annually. They are typically branched and found primarily on male members of the deer family, with the notable exception of caribou, where both male and female possess antlers. Animals with antlers include deer, elk, and moose.
In contrast, horns are permanent structures with a bony core covered by a sheath of keratin, the same material found in human fingernails. Horns are generally unbranched and continue to grow throughout an animal’s life. They are present in both males and females of many species, such as cattle, sheep, goats, and bison. Unlike antlers, horns are never shed.
The Purpose of Antlers
Antlers serve several important functions. Their primary role is in intraspecific competition, particularly among males, for dominance and mating access. Males use their hardened antlers for sparring and fighting to establish social hierarchies during the breeding season. The size and strength of antlers can signal an individual’s health and fitness, potentially influencing mate selection by females.
Beyond competition, antlers can also provide defense against predators. In some species, like caribou, antlers are used for practical tasks such as scraping away snow to access forage. The annual regrowth ensures that males have robust antlers for each breeding season.