Few herbivores are as intimidating as a rhinoceros.
The sight of a couple of tonnes of armour-plated muscle tipped with an eye-wateringly pointy front end hurtling through the undergrowth at 50kph is enough to make anyone question the strictness of its vegetarian diet.
But a rhino’s weaponry is wielded in defence, not attack.
Many cattle and antelope bear horns for similar reasons.
Rhinos, though, belong to a different branch of ungulates – one that includes horses and tapirs – and are the only ones to carry them on their nose.
Of the five species, Indian and Javan rhinos are equipped with a single horn, while white, black and Sumatran rhinos boast two, one smaller one set behind the other.
The largest horns can exceed a metre in length.
Made from bundles of keratin fibres – the stuff of hair and fingernails – bound together with glandular secretions, horns have served rhinos well in the evolutionary arms race with their predators.
But since humans started seeking them out to fashion high-status trinkets and for use in traditional eastern medicine, they have become a liability.
Hunting has caused declines not only in rhino numbers.
Historical photographs reveal that all five species are now evolving shorter horns as the best-endowed specimens are removed from the gene pool.
Main image: Black rhinos are Critically Endangered. © Martin Harvey/Getty