A Fish on the Great Barrier Reef Has Venom Like "Heroin"

The "heroin-like" venom of a fish found on the Great Barrier Reef could be developed into new painkillers, say researchers from the University of Queensland. While a bite from most poisonous fish will inflict excruciating pain on its victims, the fanged blenny—a small, fearless fish found on the GBR and around the Pacific—appears to only use its venom to slow predators down.

The UQ study, published today in Current Biology, reveals the blenny's venom has a very strange effect on its victims. Immediately after a bite, blood pressure drops by around 40 percent. But this doesn't last—the venom merely incapacitates a predator long enough so the blenny can escape the threat.

"Its venom is chemically unique," says UQ associate professor Bryan Fry. "The fish injects other fish with opioid peptides that act like heroin or morphine, inhibiting pain rather than causing it." Because the blenny's venom targets its victim opioid receptors, the predator fish will get dizzy and its movements are slowed right down. Because this venom is chemically unique, the hope is it could be used to develop new painkillers.

Associate professor Fry says the fanged blenny is one of the most fascinating fish he's ever studied, particularly how brave it is despite its small size. "Their secret weapons are two large grooved teeth on the lower jaw that are linked to venom glands," he says. The UQ study, which involved collaborators from the Netherlands and the UK, found these fangs make the blenny fairly unique within the animal kingdom. While most venomous creatures use their poison to kill predators or to stun prey to eat, the blenny's fangs are purely for self-defence.

This was discovered by tracing the blenny's evolution back through generations—it was found the fish developed its long fangs before its venom glands. For most venomous animals, the venom comes before the stinger or teeth. Bryan Fry argues the uniqueness of the blenny, from its venom to its evolution, highlights why conservation of the Great Barrier Reef is vital. "If we lose the Great Barrier Reef, we will lose animals like the fang blenny and its unique venom that could be the source of the next blockbuster pain-killing drug," he says. "This study is an excellent example of why we need to protect nature."

Recent studies of the GBR have found it's dying at a far faster rate than scientists initially believed. Terry Hughes, director of an Australian government-funded Centre for Coral Reef Studies at James Cook University, told the New York Times his team found two-thirds of the reefs in the GBR's north were already dead. "We didn't expect to see this level of destruction to the Great Barrier Reef for another 30 years," he said.

In March, the Great Barrier Reef Marine Park Authority announced the reef is experiencing yet another mass bleaching event is underway. It marks the first time bleaching at this scale has happened two years in a row. The Australian Government's plan to save the reef—focusing on water quality and land management—has faced broad criticism that it fails to tackle the underlying problem that's killing Australia's iconic reef: climate change.

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