By Jack Ashby, on 11 July 2013
There are a few things that get certain zoologists wound up. I’m not talking about extinction and Jeremy Clarkson, I’m talking about relatively meaningless* distinctions that we like to pick up on when people land on the wrong side of an invisible dichotomy. You can get blood boiling by referring to sabre-toothed “tigers” rather than “cats”; failing to say “non-avian” when referring to extinction of dinosaurs; or describing apes as monkeys (actually that’s technically true as apes evolved from monkeys and the rules of taxonomy therefore require apes to be monkeys). Among such picked-nits is the difference between horns and antlers. If only more people would remember this then fewer zoologists would die prematurely of high blood pressure…
This is the easy bit. ONLY deer have antlers. If it isn’t a deer it doesn’t have antlers. If it is a deer it doesn’t have horns.
Also, if it’s at all branched, it’s an antler (and therefore on a deer)**
Antlers are made entirely of bone: they are outgrowths of a nob on the frontal bone called a pedicle. Only male deer have antlers*** – they are used for fighting over mates. Deer grow their antlers every year in preparation for the breeding season, and then shed them once it’s over. They are often said to be the fastest growing bones in the animal kingdom. This is made possible by a highly vascularised tissue called velvet which covers them while they grow and falls off in rotting strips when they’re ready. The giant deer, when it was alive, would grow and shed my body weight in antler every year (incidentally, the giant deer’s scientific name Megaloceros means “giant horn” which is clearly nonsense).
This is a lot more complicated as loads of animals have horns (see below) – it’s a term used to describe many pointy things on animals heads (excluding noses and antlers) but most of the confusion is with the mammals. Essentially, if it isn’t on a deer, it’s a horn (and remember, if it is on a deer, it’s an antler).
Bovids are the main horny mammals – sheep, cattle and antelope. Their horns have a bony centre which is then covered in something us zoologists technically describe as horn. This can cause some confusion as “horn” can be used to describe the whole pointy thing, and the sheath of keratin that is on the outside of it. As such, bovid horns are part of the skeleton AND part of the skin.
Keratin is a protein which is used to build fingernails, claws, hair, beaks, mammal horn, bird and reptile scales and whale baleen. Handy stuff.
Horns are not shed and tend to grow throughout an animal’s life****. Depending on the species, both boys and girls can have them, though often the girls’ horns are smaller.
The other famously horny mammals are the rhinos. Rhino horn does not have a bony core – it’s just solid keratin growing from the skin. Unless you have horns, keratin has no medicinal or magical powers. The ill-informed think it cures all manner of ills, but all such beliefs do is drive some of the largest living mammals to extinction, make scumbags rich and potentially poison the ignorant.
Occasionally a person may refer to the things growing out of a giraffe’s head as “horns”. This will also rile the pedantic zoologist. Giraffes have ossicones. These are bony protuberances, much like a deer’s pedicle (but unlike antlers or horns), but they remain covered in skin and fur.
I could end there with the hope that some zoologists’ lives have been saved, but the keen can read on about the horns of ten non-mammals with horns…
1) Horned frogs have protuberances of the skull, made of bone and covered in skin.
2) Horny toad is another name for the horned lizard
3) Horned lizards have bovid-like horns, in that the horns have bony cores covered in keratin (scales).
4) Horned viper just have enlarged scales.
5) Rhinoceros beetles have a massive outgrowth of their carapace.
6) Stag beetles have massive mouthparts which look like antlers (not horns).
7) Hornbills have a huge casque made of bone (and covered in skin)
8) Two horned cow fish have bones covered in skin
9) Triceratops (and other horny dinos) have bones covered in keratin, like a cow.
10) Narwhals***** have a massive incisor.
** Exception: prongorn horns are branched (hence the prong), but pronghorns are not deer.
***Exception: female reindeer also have antlers (but not horns)
****Exception: pronghorns’ horns grow from the end if a pedicle and are shed. They are also referred to as American antelope, but they aren’t antelope (because they shed their horns) and belong to a family all of their own.
*****Ok, that’s not a non-mammal
Jack Ashby is the Manager of the Grant Museum of Zoology.