SEE IT: Endangered Mussel Squirts Offspring Into The Air

The endangered freshwater mussel, Unio crassus, squirts out regular water jets that land in the river water up to a meter away. UNIVERSITY OF CAMBRIDGE/SWNS

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 surface and attracting fish for the mussel larvae to attach to.

Researchers at Cambridge’s zoology department said in a report that the “squirting cycles” lasted between three and six hours.

Lead author of the report Professor David Aldridge, said: “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? It’s amazing!”

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

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

The researchers think the mussels squirt water jets to increase the chances of their larvae attaching to the correct host fishes.

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

This aerial view shows the endangered freshwater mussel, Unio crassus, before (left) and during (right) a water jet squirt. Who would have guessed that a mussel, which doesn’t even have a head or brain, would know to travel to the river margin and spray water back into the river during spring, reveals a study. UNIVERSITY OF CAMBRIDGE/SWNS

The study was carried out during spring.

Each mussel produced six squirts, which were taken out for investigation and found to contain live mussel larvae.

No anecdotal proof of this behaviour existed up to this point, and some experts hypothesised that the water jets might be the mussel expelling waste.

This behavior could explain why Unio crassus is an endangered species.

It becomes vulnerable to floods, the loss of river borders, and predators like mink when it climbs out of the water to spray.

The Woolf Fisher Trust funded this research, and the report was published in the journal Ecology.

Produced in association with SWNS Talker