### body part | horn:

Antler
* Most antlers have forks
  - serve sexual functions
* Some antlers are part of deer
  - fawns
  - moose
  - muntjacs
  - reindeer
  - protected by layers
  - grow throughout summer
  - have shapes
* also provide an important calcium source for small mammals.
* are a renewable product, produced every year
  - sign of male fitness and health, and are usefully thought of as a handicap
  - all bone without a covering of keratin, but unlike horns, are shed every year
* are an amazing feature of white-tailed deer
  - ancient archetype repressenting male energy, strength, and fertility
  - extension of bone
  - bone which project outward from the bucks head
  - bone, and are shed annually
  - bones, which protrude from the buck's head
* are bony outgrowths of the frontal bones of male deer
  - deciduous, meaning they are shed and grown new each year
  - different from horns
  - extensions of the skull grown by members of the deer family
* are grown and shed periodically, as a rule annually, and are usually branched
  - in the spring and shed in the winter each year
* are made from bone and grow from the front of the skull in the summer
  - of true bone that is fed by blood carried by the outer velvet covering
  - most dense on young deer and tend to become more porous as the animals grow older
* are part of deers
  - mooses
  - produced yearly by male elk, but the size of the antlers changes as the elk ages
  - pure bone, bone that grows right out of the heads of male members of the deer family
  - rich in calcium and minerals
* are shed annually and are made of bone
  - during the winter and regrown each spring
  - each year and, except in reindeer, are grown only by males
  - every year and reach their largest size during the breeding season
  - solid, composed of blood, protein, and minerals, and dropped off late each winter
  - temporary projections of bone, which are grown and discarded each year
* are the bony growths on the foreheads of most male deer
  - most unique trait of all members of the deer family
  - true bones and are composed of calcium and phosphorous
  - unique in that they are the only mammalian organs that regenerate annually
* are used as weapons during breeding season combats between bucks
  - to push an opponent off-balance, and then canine teeth are used to wound
  - usually just spikes
  - very large and prized by hunters
* begin as knobs covered in soft, thin skin called velvet
  - layer upon layer of cartilage that slowly changes into bone
* begin growing in the spring as skin-covered projections
  - of each year when the days begin getting longer
  - to grow in the summer and fall off during the winter months
* can grow up to an inch a day.
* develop into every size and shape.
* differ from horns in being annually shed and regrown each year.
* emerge in the spring and grow throughout the summer.
* fall off after the mating season.
* form only on males and their growth is controlled by the male sex hormone.
* get larger each year, as the buck grows older.
* grow and are shed each year by animals such as deer, elk and moose
  - as highly vascular spongy tissue covered in a skin called velvet
  - from spring until fall
* have a covering of living skin called velvet
  - beneficial effects
  - compositions
* includes corpi.
* normally occur only in males and are formed and shed each year.
* play an important role in deer society.
* regrow in summer and are fully grown by the fall mating season.
* remain hard and polished until they are shed in late winter.
* serve functions
  - to establish a dominance hierarchy among bucks
* shed by large animals are a source of minerals for smaller animals.
* start as living tissue.
* take about four months to grow.
* typically emerge at one year of age.
* vary from simple spikes to enormous, branched structures.

### body part | horn | antler:

Deer antler
* are a different kind of growth.
* can grow up to two centimetres a day.