An international team of scientists says the absence of sharks from abyssal regions of the world's oceans may mean some species are in danger of extinction.
The findings mean the world's oceans are about 70 percent shark-free, researchers said.
The oceans' abyssal zone remains in perpetual darkness at depths below 6,560 feet, with immense pressures of nearly five tons per square inch at its deepest.
It had been hoped that, as man explored deeper into the abyss, new shark species would be discovered. Scientists do not know why sharks are absent from the deep, but suggest one possible reason might be a lack of food.
They warn their finding has environmental implications. Professor Monty Priede, director of Oceanlab at the University of Aberdeen in Scotland said: "Sharks are already threatened worldwide by the intensity of fishing activity, but our finding suggests they may be more vulnerable to over-exploitation than was previously thought."
The findings are published in the Proceedings of The Royal Society, Biological Series.
Copyright 2006 by United Press International
Related stories:
Electronic tracking system allows scientists to tail white sharks more effectively
It's hard to study a creature when you only catch fleeting glimpses of it. Up until recently, that was one of the big stumbling blocks for marine biologists and ecologists, but advances in electronic tracking technology have allowed them to peer farther across, and deeper under, the surface of the oceans than ever before.
Unveiling the underwater ways of the white shark
It's hard to study a creature when you only catch fleeting glimpses of it. Up until recently, that was one of the big stumbling blocks for marine biologists and ecologists, but advances in electronic tracking technology have allowed them to peer farther across, and deeper under, the surface of the oceans than ever before.
Whaling commission buys time to resolve thorny issues
The International Whaling Commission agreed Tuesday to put off votes on a Japanese bid to resume commercial whaling and an environmentalist initiative to create a whale reserve in the South Atlantic.
Jellyfish outbreaks a sign of nature out of sync
The dramatic proliferation of jellyfish in oceans around the world, driven by overfishing and climate change, is a sure sign of ecosystems out of kilter, warn experts.
New study shows shallow water corals evolved from deep sea ancestors
New research shows that the second most diverse group of hard corals first evolved in the deep sea, and not in shallow waters. Stylasterids, or lace corals, diversified in deep waters before launching at least three successful invasions of shallow water tropical habitats in the past 40 million years. This finding provides the first strong evidence that a group of deep-sea animals invaded and diversified in shallow waters.
Ebb and flow of the sea drives world's big extinction events
If you are curious about Earth's periodic mass extinction events such as the sudden demise of the dinosaurs 65 million years ago, you might consider crashing asteroids and sky-darkening super volcanoes as culprits.
When it comes to nitrogen, the 'fix' is in
The discovery in the last decade of new suites of microorganisms capable of using various forms of nitrogen -- discoveries that have involved a number of University of Washington researchers -- is one reason to rethink what we know about the nitrogen cycle.
Clue to mystery crustacean in parasite form
First identified in 1899, y-larvae have been one of the greatest zoological mysteries for over a century. No one has ever found an adult of these puzzling crustaceans, despite the plethora of these larvae in plankton, leading generations of marine zoologists to wonder just what y- larvae grow up to be. A study published in BioMed Central’s open access journal,
BMC Biology, reports the transformation of the larvae into a previously unseen, wholly un-crustacean-like, parasitic form.