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Animals With Antlers
Animals With Horns
Rocky Mountain Elk
What is the difference between antlers and horns?
Many of the larger herbivores (plant eating animals) of North America have either antlers or horns.
ANTLERS- Antlers are found on members of the deer family and are usually grown only by males. They are a bone-like growth that is shed and re-grown every year. Antlers are usually branched and have multiple points.
HORNS- Horns are grown by members of the sheep, goat and cattle families. They are made of a sheath of specialized hair follicles that grow over a bone core. Horns are not shed, but continue to grow throughout the life of the animal. Both males and females grow horns, but the horns grown by males are usually much larger. Horns do not usually fork or branch.
The Exception to the rule
Never say never or always when you're talking about nature, it seems there are exceptions to most rules.
As it’s name implies, the pronghorn grows a horn that has a prong or branch. Sometimes incorrectly called an antelope, the pronghorn is also different because it sheds it’s horn sheaths every year.
Top to bottom left to right: Horns (Rocky Mountain bighorn sheep), Antlers (Rocky Mountain elk), Horns (mountain goat), Antlers (white tailed deer), Horns (bison), Antlers (moose), Horns (pronghorn), Antlers (mule deer), Horns (desert bighorn sheep).
How do antlers grow?
Each year male members of the deer family shed their antlers. The growth and shedding of antlers is triggered by the changing length of daylight in the spring and fall called photoperiodism. The antlers drop off in the fall and then in early spring start to grow again. Knobby bumps on a deer’s skull called pedicles are where the antlers start to grow.
Antlers are one of the fastest growing tissues in the world. To give you an idea of how fast antlers grow, an elk can grow a set of antlers five feet long that weighs more than 30 pounds in about four months.
While the antlers are growing they are covered by a fuzzy skin that has a lot of nerves and a plentiful blood supply. This fuzz is called velvet and supplies the growing antler with the nourishment it needs to grow.
Because there are so many nerves in antler velvet it’s very tender and animals that are “in velvet” try to avoid bumping their antlers.
The skull on top is from a male deer. You can see the bony part, called a pedicel, where the antlers grow. the bottom skull is from a female deer and has no pedicels and can’t grow antlers.
The picture of a shed antler shows the base (called a burr) where the antler separated from the skull.
By mid August or early September the antlers stop growing and the velvet dies, dries out and starts to fall off. This seems to itch and the animals rub against trees and bushes to rub the velvet off. By this time the bony part of the antlers is hard and strong and contains no nerves so it’s not painful for the animals to bump against things.
As you can see in the pictures above and on the right, when velvet comes off the hard antler is very light in color. Darker antlers are the result of staining from the juices of the plants the antlers are rubbed against.
The breeding season, often called the “rut,” begins after the antlers are hard. The males use their antlers to hurt or intimidate rivals.
After the rut, photoperiodism again comes into play. As the days start to grow longer in late winter, nature signals the deer to shed their antlers and the process starts over.
Most deer and elk tolerate cold temperatures better than really hot ones. Studies show that humans are very comfortable at about 72 degrees fahrenheit. At that same temperature deer and elk start to show signs of stress. Antlers in velvet can help keep these animals cool.
Because there is a high supply of blood to the growing antlers, the blood flowing through the velvet can be cooled. If the animal lays in the shade and there is a little breeze, the blood can be much cooler than the animals body temperature. This helps cool the animal in the same way as a car radiator helps keep the engine cool.
Watch a slideshow of elk antler growth
How do horns grow?
Unlike antlers, horns (with the exception of those grown by pronghorns) are not shed, but continue to grow throughout the life of the animal. Both males and females grow horns over a bony core that extends from the skull. The horns themselves are made of keratin which is similar to what our fingernails are made of.
Some horns show a distinct ring for each year of growth. Many animals have fluted or spiral shaped horns. North American wildlife grow a more simple curved horn.