A vial of white parasitic worms left for decades in a Tasmanian museum may help solve a timeless mystery: why do whales strand themselves on beaches?
The worms were collected from the blowhole of a pilot whale that beached itself in 1973 and then stored in Launceston’s Queen Victoria Museum and Art Gallery.
The vial attracted little attention until Australian researchers discovered it and identified the thin, long worms as rare parasitic nematodes.
A study from Charles Sturt University and the Czech Academy of Sciences has now raised questions about the role of parasites in whale strandings, a recurring phenomenon that often kills dozens of whales around Australia each year.
“We already know that parasites cause suicide in many other animals,” co-author and parasite expert Dr Shokoofeh Shamsi told Guardian Australia. “Why shouldn’t they do in whales?”
The pilot whale that beached itself in 1973 was infested with thousands of parasitic nematodes that may have eaten away at its blowhole.
Shamsi said the parasite infestation could have limited the whale’s ability to navigate, leading it to accidentally swim to the beach.
It is estimated about 2,000 stranding events happen globally each year.
Scientists have no conclusive understanding of why whales maroon themselves on the sand but suggestions include agedness, illness, injury, severe weather, escaping predators or disorientation due to loud sounds.
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Pilot whales are particularly prone to mass strandings, potentially due to strong social bonds that encourage the whales to follow an unwell leader towards the shore.
While Shamsi said it was likely the worms played a role in the whale’s death, other experts emphasised the need for further research.
Dr Olaf Meynecke, a Griffith University whale researcher, said parasite presence was more likely a symptom of pre-existing illness than a direct cause of the stranding.
“Parasites can really only take over and kill a host when the host is unwell to start with.”
Meynecke said the discovery demonstrated the need to check for parasites and investigate the blowholes of stranded whales.
Shamsi said more analysis of parasites and blowholes in stranded pilot whales was needed. “Parasites could be part of this stranding that we see in whales, and because no one really examined the blowhole for parasites, we don’t know the answer.”
Wildlife scientist Dr Vanessa Pirotta said the study showed it was vital to take samples from whales when they stranded themselves but emphasised the parasite theory was not conclusive.
“Potentially, this may be a cause,” she said. “It’s one small piece of the puzzle for us understanding, potentially, why they strand.
“It is one of those things in the science world that remains a mystery.”
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