British researchers have filmed endangered mussels squirting their offspring through the air—a never-before-seen tactic believed to increase their lifespan.

Experts at the University of Cambridge filmed female mussels—which don't have a head or brain—moving to the water's edge and anchoring into the riverbed. With their back ends raised above the waterline, the freshwater mussel (Unio crassus) squirted jets of water containing viable mussel larvae.

They shot long distances from the banks of the Biała Tarnowska River in Poland, disturbing the river's surface and attracting fish to which the mussel larvae could attach themselves.

Researchers at Cambridge's department of zoology said in a report the "squirting cycles" lasted between three and six hours.

"Who'd have thought that a mussel, that doesn't even have a head or a brain, knows to move to the river margin and squirt jets of water back into the river during springtime?" said lead author of the report, Professor David Aldridge. "It's amazing!"

Unlike other mussel species, Unio crassus has a limited range of suitable host fishes. They include minnows and chub.

These species were attracted to the falling water jets, the researchers said.

They think the mussels squirt water jets to increase the chances of their larvae attaching to the most beneficial host fishes.

By being squirted into the air and not the water, shown in the video below, the larvae are propelled greater distances from the parent mussel.

Six squirts were collected from each mussel for analysis, and researchers confirmed they contained viable mussel larvae.

Before now, there was only anecdotal evidence of this behavior, and some scientists thought the water jets might be the mussel expelling feces.

This behavior could explain why Unio crassus is an endangered species: Climbing out of the water to squirt makes it vulnerable to floods, destruction of river margins, and predators like mink. And its need for specific host fishes links its survival to theirs.

Understanding how this species completes its life cycle is important for its conservation under changing environmental conditions.

The study carried out during spring, funded by the Woolf Fisher Trust, was published in the journal Ecology.

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