It looks like a small chipolata sausage to which some joker has tastelessly attached the front end of a mole cricket. This apparent chimaera of a creature, however, is real.
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What is a sandgroper?
The sandgroper is a kind of grasshopper that's seriously good at surviving in Australia’s harsh and arid sand-lands. The 14 species are collectively known by the rather descriptive scientific name, Cylindrachetids.
How big are sandgropers?
Some sandgropers are quite large, growing to 7-8cm long, but they are rarely seen and, given their highly specialised subterranean lifestyle, this isn’t much of a surprise.
They are peculiar to look at because everything about them is honed to their hypogean ways beneath the sand’s surface. Here they can shelter, avoid predators and find cooler, more humid conditions away from the dehydrating effects of the sun and wind. It’s a good gig if you can handle the challenges of living in an ever-changing, shifting and abrasive habitat.
What do sandgropers look like?
The sandgroper has a long, lithe body, a bit like a subway train, which presents as little frontal area to the sandy soil as possible. Its ‘engine’ at the front end drags behind it the ‘carriage’ of its soft, elongated abdomen. The head and thorax are terra-dynamic (it’s a thing), tough and shiny. The pointed head-capsule, short antennae and almost non-existent eyes all help to reduce resistance to the substrate it burrows through. But it is those front legs, looking like ears on a worm, that catch the eye.
They are analogous to those of a mole – short, strong and powerful. What is missing are those little foot segments or ‘tarsi’ found at the ends of the legs of most insects. In sandgropers these limbs are reduced to the first pair of segments, which are shortened and flattened to form highly effective shovels.
The other two pairs of legs, complete with eye-catching pale patches that look like beads, are similarly reduced and unlike the limbs of any grasshopper. There are also no jumping legs at the rear. Instead, the last two pairs of legs recess into depressions in the sides of the insect’s thorax. Here, they can be tucked away when not being used to drag the insect to and fro in its tunnel.
Are sandgropers mole crickets?
For an entomologist, many of these features echo those found in mole crickets (another specialised burrowing insect), and it’s tempting to conclude they’re related. But a closer look reveals that sandgropers have short antennae compared to the long ones of mole crickets (another bizarre animal that lives underground); the latter also have wings.
What the sandgroper exhibits is a fabulous example of nature independently finding its best solution to a specific set of environmental challenges in two groups of unrelated animals – something called convergent evolution.
How do sandgropers move about?
Sandgropers are compression burrowers, forcing sand particles out of their path using their front limbs in a kind of breast-stroke action. In loose sand they literally swim through, but in slightly firmer ground they form tunnels and galleries. After rain, the surface tunnelling efforts of the males (perhaps looking for females) leave characteristic raised ridges on the surface of the sand – one of the few clues to their existence.
For the rest of their lives, they remain in their underworld. Despite the paucity of records for the 14 or so known species, the reality suggests they can exist in large numbers under our very feet. Excavations down a couple of metres have revealed an astonishing count of around 100 for every square metre of sand surface.
What do sandgropers eat?
Despite being blamed for damaging crops and grassland in Western Australia, little is known about the sandgroper’s diet. Gut analysis of a few suggests they are omnivorous, eating a mixture of plant material and other invertebrates. They are even partial to a bit of cannibalism, if the opportunity presents itself.
How do sandgropers hatch?
Unlike regular grasshoppers, which lay clusters of small eggs, sandgropers develop from large eggs that are laid individually, each within its own cell, suspended by a thread. Eggs are white, pink or deep red and relatively large – up to 7mm long. Development is slow and the sandgroper’s life-cycle extends over several years.
Are sandgropers poisonous?
Despite appearances, sandgropers are not poisonous.
Read more of Nick's columns
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- Deep in the Malaysian forest, I found a prehistoric-looking insect that's left scientists puzzled for hundreds of years
- These animals may all be female, but that doesn't stop them enjoying sex – thanks to a bit of role play
- “If you’re stung, you must have sex within 24 hours or you’ll die” – the legend behind the insect that looks like a peanut
Main image: a sandgroper in The Amadeus Basin, Northern Territory, Australia. Credit: Getty
