Env Sci Headgear Notes

Specialized Headgear
Antlers and Horns
Public Demand
• The demand for antlers and horns of many
different animals has fueled illegal hunting
and trafficking
– Rhino horns: used for dagger handles in the
middle east, ground into powder it is used to treat
fevers in traditional Chinese medicine
– Elk antlers: Sold as an aphrodisiac (sometimes
$200 per ounce)
• Become a problem in America’s national parks
What does the forensic scientist need
to know?
• Forensic scientists are often sent parts from
police seizures
– First must identify from which animal the
antler/horn came
– Must be able to tell the season the antler was
• Ex: Federal law says antlers in velvet must be treated
w/ formaldehyde
• Chemical tests can be run
Anatomy of Horns
• Horns are a
permanent part of the
animals skull and have
3 layers
• Both males and
females have horns
(female usually smaller
• Horns are not shed
– Except American
Pronghorns, who shed
the keratin sheath once
a year
Anatomy of Horns
• Inner layer: extends up from the skull as a bony
• Middle layer: called the sheath, it is a thin layer of
blood-vessel-rich tissue that supplies blood to the
outer layer
– The sheath continues to grow throughout the animal’s
• Outer layer: called the keratin layer, it is the
“horn” as we know it
– Keratin is a protein that is also found in fingernails and
Anatomy of Antlers
• Antlers grow from the
skull and are shed
once each year
• Made of bone that
grows from two disc
shaped bumps on the
skull (Pedicles)
Anatomy of Antlers
• During the months when the antler is
growing, the soft cartilage is covered by
blood-vessel-rich skin called velvet
– When the antler is finished growing, this tissue
dies, the cartilage hardens to bone, and the velvet
falls off
• In all but one species (Caribou), only males
grow antlers
How big do antlers and horns grow?
• The size of a male’s antlers or horns tell a story
– To grow large antlers, a male must be well fed and
– Has to carry the weight
• Elk antlers can weigh up to 25-40 lbs.
• Bighorn sheep horns can weigh as much as 30 lbs.
• So what’s the purpose?
– Rutting (mating) season is the one time males
gather with female herds
– Males battle with their headgear for territory and
Antlers Through the Seasons
Spring to Mid-Summer
• Spring signals the start of new antlers
• Soft layers of cartilage grow from pedicles
• Grow very rapidly
– Ex: moose antlers can grow 1 inch per day
• But why?
– An increase in daylight triggers the body to make
high levels of the male hormone testosterone
– This hormone stimulates antler growth
Late Summer
• Antlers begin to harden into bone
• Velvet begins to fall off
– Males can be seen rubbing their antlers on trees
to shed the velvet
• But why?
– Blood stops flowing through the velvet, causing
the living tissue to die
Early Fall
• Antlers are cleaned of all velvet
– Marked with grooves and ridges where the blood
vessels used to be
• Remain firmly attached to the skull
• This is the season of rut (mating)
– Use their antlers to battle for territory closest to
• But why?
– Testosterone remains high
– Keeps antlers in place, but also affects behavior
Late Fall to Winter
• Rut and mating season ends
• Males go off on their own
• Antlers fall off
– Males can be seen rubbing partly attached antlers
on trees to help things along
– Can lose one antler at a time
• But why?
– Testosterone levels drop dramatically
– Antler is no longer held to pedicle