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Carnivorous sea squirt: Venus fly trap of deep

AFP

Conservation

waffle cone sponge

The half-metre-wide mouth of a 2-metre high "waffle-cone" sponge, found at a depth of 2197 m in the Tasman Fracture Zone. The Tasman Fracture Zone is approximately 350 km south-west of Hobart.

Credit: Advanced Imaging and Visualization Laboratory WHOI

anthomastid

A bright red, undescribed species of shell-less coral, called an anthomastid or gorgons-head coral, at 1700 m deep at the Cascade Plateau, off south-east Tasmania.

Credit: Advanced Imaging and Visualization Laboratory WHOI

deep-water ascidian

One of Australia's deepest residents – a bizarre carnivorous sea squirt, or ascidian, standing half a meter tall on the seafloor on the Tasman Fracture Zone at a depth of 4006 metres. The animal feeds opportunistically, triggered when a fish or any other swimming organism touches it. The animal is then trapped by the funnel-like front section, which collapses around the prey item.

Credit: Advanced Imaging and Visualization Laboratory WHOI

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SYDNEY: Biologists have uncovered new marine animals in a search of previously unexplored Australian waters, including a bizarre carnivorous sea squirt and ocean-dwelling spiders.

A joint U.S.-Australian team spent a month in deep waters off the coast of the southern island of Tasmania to "search for life deeper than any previous voyage in Australian waters," said lead scientist Ron Thresher with Australian government research agency the CSIRO's Marine and Atmospheric division.

Millions of purple spotted anemones

What they found were not only species new to science – including previously undescribed soft corals – but fresh indications of global warming's threat to the country's unique marine life.

"Our sampling documented the deepest known Australian fauna, including a bizarre carnivorous sea squirt, sea spiders and giant sponges, and previously unknown marine communities dominated by gooseneck barnacles and millions of round, purple-spotted sea anemones," Thresher said.

(Seee more pictures on the related blog here)

Using a submersible car-sized robot named Jason, the team explored a rift in the Earth's crust known as the Tasman Fracture Zone, a sheer two-kilometre drop to 4,000 metres below the ocean's surface.

Blogging on board the ship, researcher Adam Subhas of Haverford College in Pennsylvania, U.S., said the team witnessed some "cool biology" as they descended the fracture, including the sea squirt, which he described as "basically an underwater Venus fly trap, but much bigger."

Spring-loaded

The sea squirt, also known as an ascidian, stands 50 cm tall on the sea floor at a depth of just over 4,000 metres. It traps prey in its funnel-like front section if they touch it when they swim past.

"The geology was fascinating too – the sediment was incredibly fine and lightly packed; it made me think of powder snow," Subhas wrote.

Fossil coral fields were found, dating back more than 10,000 years. Thresher said samples taken would provide ancient climate data for use in global warming projections.

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