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Monday, 13 June 2011

Scientists thought that sawfish used their saw to probe the seabed for food.  But a Cairns researcher has found that these large (5 metres or more) and endangered fish actually use the saw to locate and dismember free-swimming fish.

In Melbourne this week as a winner of Fresh Science, researcher Barbara Wueringer said some of the subjects she studied in Cairns were residents at the Melbourne Aquarium, the only aquarium in the world with freshwater sharks and sawfish.

Ms Wueringer's work is being presented for the first time in public through Fresh Science, a communication boot-camp for early-career scientists held at the Melbourne Museum.  One of 16 winners from across Australia, she works at the universities of Queensland and Western Australia and with Cairns Marine, an aquarium fish collecting company.

Ms Wueringer said the sawfish saw - an elongation of their head with teeth along its sides - provided a sixth sense.  "It is packed with thousands of tiny pore-like organs which can detect the minute electric fields surrounding living organisms, and it can also be used to attack its prey," she said.

"Northern Australia is considered to be the last stronghold in the world for four species of sawfish but if we do not understand these animals, we will not be able to save them."

Sawfish are beautiful and mystic ancient predators, according to Ms Wueringer.  They are regularly taken as by-catch in fisheries, and their fins and saws are traded as highly priced medicines, curios and culinary delicacies. The saws are packed with sensors known as ampullary pores which can detect electric fields, the distribution of which is influenced by how the sawfish captures its prey.

Ms Wueringer compared the distribution of ampullary pores in four species of sawfish, which inhabit remote ecosystems in northern Australia.  She found that sawfish had much more concentrated collections of pores on the upper side of the saw than their relatives the shovel-nosed rays.  This indicates that they use their saw to detect prey in the three-dimensional space above the saw.

Ms Wueringer's supervisor, UWA Winthrop Professor Shaun Collin, said her work was changing our understanding of how sawfish live and hunt, and would contribute to global efforts to conserve these majestic creatures.

Fresh Science is a national program sponsored by the Australian Government.

Media references

Barbara Wueringer (+61 4) 31 519 524
Sarah Brooker (Fresh Science)  (+61 4) 13 332 489
Niall Byrne (Fresh Science)  (+61 4) 17 131 977
Sally-Ann Jones (UWA Public Affairs)  (+61 8)  6488 7975  /  (+61 4) 20 790 098

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