Friday, October 01, 2010

Happy October First!

Yes, tis the first of October and the testosterone levels of the beast above are increasing. This deer in our yard is showing nice antler development. I have a friend who said that his horns are growing! As a biologist, I had to point out the difference between horns and antlers.

Found on both male and female animals in some species, horns continue growing throughout the life of particular creatures. Made of keratin, a substance making up hooves, hair, and nails, horns appear as bony growths under the skin formed from connective tissue. Growing separate from the skull bone, horns become a protruding bone-like extension from the head. Horns have an interior of pulp which contains blood vessels along with connective tissue. Animals with horns include hoofed, even-toed cattle, sheep, and goats. Unlike antlers, most horns never shed.

Antlers, on the other hand,
are found mostly on males: only caribou and reindeer have antlers on the females, and these are normally smaller than those of the males. Nevertheless, fertile does Each antler grows from an attachment point on the skull called a pedicle. While an antler is growing, it is covered with highly vascular skin called velvet, which supplies oxygen and nutrients to the growing bone; once the antler has achieved its full size, the velvet is lost and the antler's bone dies. This dead bone structure is the mature antler, which is itself shed after each mating season.

Antler shedding occurs from the middle of December to the middle of February. The antlers do not last long on the forest floor since they are a great source of nutrition for mice and other critters.

When I taught Comparative Vertebrate Anatomy, I would always point out specialized horns that included the rhinoceros with its hairlike horn. You may wish to research the unique horns found on such mammals as the American bison, the giraffe, big horned sheep, and the African buffalo.


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