You don’t have to be huge to leave a mark and neither does the mark you leave need to be huge in order to have an impact.
In the rivers and estuaries of New South Wales and Queensland in Australia, swims a little fish that proves that point.
The bullrout, when approached, tends not to flee but instead stands its ground and shows some bristle, raising its dorsal fin in defiance. It may seem a risky strategy, but that dorsal fin is lined with venomous spines that deliver instant, intense pain. Any animal, bird or human on the receiving end is likely to recoil in agony before the bullrout gets squashed or eaten.
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The sole member of the genus Notesthes, the bullrout is part of the subfamily Tetraroginae, that comprises wasp-fish and scorpionfish. Although tolerant of saltwater, the bullrout is more often found in creeks, streams and rivers, where it lives a largely sedentary life as an ambush predator.
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How big are bullrout and what do they look like?
They rarely exceed 20cm in length, and are plump in shape, with a large mouth, scaleless head and prominent fins. The body is covered in small scales and is mottled in olive green and brown, creating a pattern that provides perfect camouflage for a life spent in relative stillness on the riverbed.
The spines of the anal and pelvic fins contain venom glands and there are also 7 on the operculum - the hard, bony flap that covers and protects the gills.
The 15 spines that comprise the dorsal fin are the most prominent, and, when raised, they run along a large proportion of the fish’s back. This armoury makes the bullrout a prickly proposition for potential predators, which would likely spit out their meal once spiked. The spines also make for quite the threat to unwary waders.
Where are bullrout found?
Bullrout are often found close to submerged roots and underwater debris, or close to man-made structures like weirs or the piling beneath bridges. This means they are often located in spots where people might swim or paddle, or where pet dogs might be encouraged to cool off.
The purpose of bullrout venom is not to incapacitate or kill but instead inflict pain so severe as to deter. It contains an algesic protein that stimulates the sensory nerve endings and registers as excruciating agony. The renowned Australian naturalist Sir John Cleland wrote in 1912 that, “the pain is intense. It runs through the whole limb like fire.”
An observation supported by at least one contemporary YouTube video that shows an individual deliberately spiking themselves on a bullrout spine. Unwise, not least for the unnecessary stress it causes the fish.
The puncture wound is small, just a couple of millimetres long, but the spine will often break off inside the skin. The resulting pain is unremitting and can persist for several days, but can be relieved, almost instantly, by immersion in hot water. Something to consider if you happen to be wading barefoot in an Eastern Australian stream…
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