No Job Too Dirty: A Peculiar & Resourceful Ecological Niche

A popular television program ‘Dirty Jobs‘ follows charismatic host Mike Rowe as he explores some of the messiest and challenging careers across North America. After eight seasons of mud, grime, filth, insect-frass, fish guts, and bat guano, Rowe announced that 2008 would mark the programme’s final season. As each episode famously began:

“My name’s Mike Rowe, and this is my job. I explore the country looking for people who aren’t afraid to get dirty — hard-working men and women who earn an honest living doing the kinds of jobs that make civilized life possible for the rest of us. Now, get ready to get dirty.”

The sheer diversity of jobs that Rowe profiled within eight exciting seasons captured wholeheartedly the interest and imagination of millions.  However, it’s important to note that, relatively speaking, humans don’t have it so bad. Though it would be a very interesting debate, there is one particular group of organisms that might have drawn the shortest straw: dung beetles.

If you think your job is ‘crappy’, then dung beetles have you beat. Dung beetles have learnt to exploit a resource that most are perfectly happy to avoid. What resource? Dung, of course! Dung beetles can be broadly classified into three different behavioural groups. The first are telecoprids – these represent the ‘quintessential dung beetles’ – males form and roll dung balls away from the dung pat to impress females. Ultimately, a successful male will end his day by digging the ball into the ground where the female will deposit an egg. Paracoprids have the joy of meeting at the dung pat, then digging tunnels beside or directly beneath the dung pat. The beetles then partition dung within the tunnels for the larvae to subsist on. Finally you have the endocoprids who hang-out, breed, and lay eggs freely within the cozy confines of a dung pat.

In the United Kingdom, our dung beetles fall into into the two latter groups – most species represented by a small-bodied and diverse genus ‘Aphodius’. Most dung beetles live in pasture environments and feed on the dung of livestock; others are are adapted to forests ecosystems and are dependent on dung from deer and rabbits. Meandering from dung pile to dung pile doesn’t necessarily sound like the most glamorous existence, but compared to the life history of certain tropical species, our British beetles are living lavishly.

Though it could be argued that all dung beetles are employed with rather dirty jobs – one guild of beetles has taken the ‘gross factor’ up an entire magnitude. This was achieved simply by utilising a peculiar tropical niche. These beetles have negotiated an intimate relationship with a charismatic jungle beast – the three toed sloth (Bradypus).

A moving ecosystem. Photo by Stefan Laube: Wikimedia

Sloths are famous for their leisurely pace, clocking in at an average pace of less than a quarter of a kilometre per hour. Sloths generally defecate once a week, climbing down from the trees to do their business in the leaf litter (Young, 1981). The dung is pelleted, and hardens quickly. Any beetles looking to use the resource must exploit it within the first five minutes (Young, 1981). To make this possible, a group of beetles has taken a very novel approach by hitching a ride in the fur of the sloth. As dung is a valuable, patchy and ephemeral resource, competition can be tough! This is likely what causes beetles to aggregate in the hair surrounding the sloth’s anus. It’s an infinitely less charming version of ‘the early bird’s worm’.

Uroxys gorgon (Arrow) – Photo by Trond Larsen

As science continues to discover more about the weird and wonderful world we live in, it’s inevitable that other strange species and behaviours will become unearthed for the world to marvel or, indeed, shudder at. It’s probably best that Mike Rowe finished with the popular Discovery series ‘Dirty Jobs’ before getting into the unique and unusual occupations of the animal kingdom. The general viewing audience might not be ready for experiencing such a filthy line of work. But in the end – despite how dirty a job can be – someone, or something has got to do it!

References:

Howden, H. F., & Young, O. P. (1981). Panamanian Scarabaeinae: taxonomy, distribution, and habits (Coleoptera, Scarabaeidae)[New taxa]. Contributions of the American Entomological Institute.

Young, O. P. (1981). The utilization of sloth dung in a Neotropical forest. The Coleopterists’ Bulletin, 427-430.