Horns Versus Antlers: a Rumination
Antlers or horns? What is the difference and does it matter? Well the answer, predictably is yes, and very much so. To answer this we need to take a closer look at the Linnaean taxonomy (how animals are classified according to the basic concentric groups of Kingdom, Phylum, Class, Order, Family, Genus and Species) and phylogeny (or evolutionary history) of ruminants. The Ruminantia is a taxon of the greater order Artiodactyla (even toed ungulates or hoofed animals), comprised of most of the large grazing or browsing animals – among them cattle, goat, sheep, giraffe, deer and antelope. These digest roughage in two steps, chewing and swallowing, then regurgitating to chew the “cud”, ensuring that as much nutritional value is extracted from the herbage as possible. The ruminal storage capacity also allows these prey animals to consume feed rapidly and then chew and digest later when less likely to be attacked by predators.
Having covered basic physiology and features of ruminants, we get back to the sharp end of the matter: as prey animals they need some form of defence and protection against predation and intra species competition for dominance and breeding rights. As herbivores, their teeth are designed for snipping and grinding plant matter into a homogenous pulp for the greater ease of digestion: thus, the (often large and magnificent) cranial appendages of horn and antler.
The family Cervidae comprises moose, elk, red, fallow and reindeer and are the sole carriers of antlers. The growth, mineralisation and casting of antlers are controlled by hormones which are regulated by photoperiod (the duration of daylight). As the days get longer in the spring, testosterone is produced in males, stimulating the growth of cartilage from a pedicle in the frontal bones of the skull, to be eventually replaced with bone and covered by “velvet”, a vascular skin with capillaries supplying oxygen to the growing bone. During rutting season in the autumn, the velvet is stripped by fenced battles for dominance, and once asserted, testosterone levels drop with the receding sunlight, the bone dies, severed by an osteoclast and is eventually shed, to be regrown next season. Contrary to popular belief, there is in fact a single species of deer native to Africa: the Barbary deer (a subspecies of Red Deer) found in Morocco.
The true horn, on the other hand, occurs only in the family Bovidae – cattle, buffalo and antelope, and is made from a hard layer of skin tissue (keratin) over a core of living bone, which continues to grow throughout the animal’s life. Growing from the base, the horn may curl or spiral but will never branch (unlike antlers). The horns of giraffe are structurally similar to antlers but are never shed. So too, Rhinoceros “horn”, is not true horn as it lacks a core of bone and is instead made entirely of keratin.
While antlers are only present in males of all Cervidae (with the exception of caribou – where the female antlers are smaller), horns are carried by females of several species of Bovid. There is a distinct correlation between diet or general habitation and the presence of horns in females: most, if not all antelope that carry horns in both sexes are either nomadic or prefer open areas (grazers) with territorial or polygamous societies: buffalo, wildebeest, eland, roan, sable, blesbok gemsbok, and springbok. Whereas kudu, bushbuck, puku, and impala tend to occupy closed vegetation, with plenty of cover and where horns are more likely to be hindrance than help in moving effectively through the bush. Females can easily hide their young using near perfect camouflage; males however still need their horns to assert dominance, fighting for territories and mating opportunities.
In summary: antlers are shed seasonally, are made of bone and branched. Their size and shape are a good indication of the dominant male hierarchy within the herd; food availability, and mineral composition of the soil – needing a considerable amount of calcium for bone growth.
Horns grow throughout the bovid’s life, are made of living bone and keratin, curling from the base outward and are used as defence from predation.
Ruminate on that.
Written by: Tara Vivian-Neal