Fishermen catch coelacanth off the coast of Indian Ocean archipelago
http://news.independent.co.uk/sci_tech/article2776120.ece
By Ali Sultan, Associated Press Writer
Published: 17 July 2007
Fishermen have caught a rare and endangered fish, the coelacanth, off the coast of the Indian Ocean archipelago of Zanzibar.
The find makes Zanzibar the third place in Tanzania where fishermen have caught the coelacanth, a heavy-bodied, many-finned fish with a three-lobed tail that was thought extinct until it was caught in 1938 off the coast of South Africa. Since then two types of coelacanth have been caught in five other countries: Comoros, Indonesia, Kenya, Madagascar and Mozambique, according to African Coelacanth Ecosystem Program.
"Fishermen informed us that they caught a strange fish in their nets. We rushed to Nungwi (the northern reaches of Zanzibar) to find it's a coelacanth, a rare fish thought to have become extinct when it disappeared from fossil records 80 million years ago," said Nariman Jiddawi of the Institute of Marine Sciences, which is part of the University of Dar es Salaam in Tanzania's commercial capital.
Trade in the coelacanth is banned under the Convention on International Trade in Endangered Species of Wild Fauna and Flora.
"Zanzibar will join a list of sites of having the rare fish caught in its own waters," said Jiddawi, adding the catch weighed 27 kilograms (59.5 pounds) and measured 1.34 meters (4.4 feet).
Four fishermen caught the fish on Saturday, Jiddawi said.
Mussa Aboud Jume, director of fisheries in Zanzibar, said that the coelacanth will be preserved and put on display at the Zanzibar Museum.
A statement of the Institute of Marine Sciences said that 35 coelacanths have been caught since September 2003 in Mtwara, a southern region of Tanzania, and mostly along the coast of Tanga in Tanzania's north.
Coelacanths are the only living animals to have a fully functional intercranial joint, a division separating the ear and brain from the nasal organs and eye, according to an Institute of Marine Sciences statement.
Showing posts with label Nature. Show all posts
Showing posts with label Nature. Show all posts
Monday, July 16, 2007
Friday, May 11, 2007
Bats' wing strokes 'defy normal rules of flight'
By Steve Connor, Science Editor
Published: 11 May 2007
Bats use wings to fly very differently to birds, according to a study that has revealed the nocturnal mammals engage in sophisticated aerial acrobatics.
One of the first detailed investigations into the aerodynamics of bat flight shows that they can hover in mid-air by flipping their wings upside down to generate lift on the upstroke as well as the downstroke.
Scientists said that bats often seemed to defy conventional aerodynamic theory because of their ability to twist and turn quickly in mid-flight to avoid predators or catch prey.
"They are a vertebrate version of the bumble bee, which is said to defy scientific logic by being too heavy to fly with such short wings. It's not been known before that bats can generate such high lift forces with their wings," said Anders Hedenström of Lund University in Sweden.
Using a wind tunnel and a fog machine, Dr Hedenström and his colleagues took high-speed video images of a nectar-eating species of bat to study the vortices of air produced by its beating wings. "One of the unusual things we saw was that when the bat flew slowly or hovered it rotated its wings by nearly 180 degrees at the turn of the upstroke and the downstroke. The underside of the wing became the upperside," he said.
A bat's wings are made of flexible membranes stretched over the extended bones of its limbs. This design requires it to keep its wings rigid to produce lift. A bird's wing, however, is naturally more rigid and employs the extra trick of being able to separate its flight feathers on the upstroke so that air can pass through the wing, rather like light passing through an open venetian blind, said Geoffrey Spedding, an aerospace engineer at the University of Southern California, who was part of the research team.
"Instead of feathers projecting back from lightweight, fused arm and hand bones, bats have flexible, elastic membranes that stretch between specially extended, slender bones of the hand," Dr Spedding said. "The bones and wing membranes both change shape with every wing beat, flexing in response to the balance between forces applied by the muscles and competing forces due to the air motion around them," he said. "Where birds can feather their wings, opening the feathers like a Venetian blind, bats must do something different. Hence they have developed a twisting wing path that increases the lift during the upstroke," he added.
The study, published in the journal Science, found that when bats fly slowly they use the rotating-wing "and this difference can be traced to the peculiar upstroke", Dr Spedding said. "That, in turn, is likely to be caused by the collapsible membrane of the bat's wing."
Bats, a protected species, are the only mammal to have evolved self-powered flight and most species are adapted to eating flying insects, consuming up to their own body weight each night. They employ a sophisticated echo-location system to catch prey as well as avoid collisions
By Steve Connor, Science Editor
Published: 11 May 2007
Bats use wings to fly very differently to birds, according to a study that has revealed the nocturnal mammals engage in sophisticated aerial acrobatics.
One of the first detailed investigations into the aerodynamics of bat flight shows that they can hover in mid-air by flipping their wings upside down to generate lift on the upstroke as well as the downstroke.
Scientists said that bats often seemed to defy conventional aerodynamic theory because of their ability to twist and turn quickly in mid-flight to avoid predators or catch prey.
"They are a vertebrate version of the bumble bee, which is said to defy scientific logic by being too heavy to fly with such short wings. It's not been known before that bats can generate such high lift forces with their wings," said Anders Hedenström of Lund University in Sweden.
Using a wind tunnel and a fog machine, Dr Hedenström and his colleagues took high-speed video images of a nectar-eating species of bat to study the vortices of air produced by its beating wings. "One of the unusual things we saw was that when the bat flew slowly or hovered it rotated its wings by nearly 180 degrees at the turn of the upstroke and the downstroke. The underside of the wing became the upperside," he said.
A bat's wings are made of flexible membranes stretched over the extended bones of its limbs. This design requires it to keep its wings rigid to produce lift. A bird's wing, however, is naturally more rigid and employs the extra trick of being able to separate its flight feathers on the upstroke so that air can pass through the wing, rather like light passing through an open venetian blind, said Geoffrey Spedding, an aerospace engineer at the University of Southern California, who was part of the research team.
"Instead of feathers projecting back from lightweight, fused arm and hand bones, bats have flexible, elastic membranes that stretch between specially extended, slender bones of the hand," Dr Spedding said. "The bones and wing membranes both change shape with every wing beat, flexing in response to the balance between forces applied by the muscles and competing forces due to the air motion around them," he said. "Where birds can feather their wings, opening the feathers like a Venetian blind, bats must do something different. Hence they have developed a twisting wing path that increases the lift during the upstroke," he added.
The study, published in the journal Science, found that when bats fly slowly they use the rotating-wing "and this difference can be traced to the peculiar upstroke", Dr Spedding said. "That, in turn, is likely to be caused by the collapsible membrane of the bat's wing."
Bats, a protected species, are the only mammal to have evolved self-powered flight and most species are adapted to eating flying insects, consuming up to their own body weight each night. They employ a sophisticated echo-location system to catch prey as well as avoid collisions
Friday, February 23, 2007
Deep sea discovery: The monsters from the deep
They're huge. They're ferocious. They were - until now - reassuringly rare. But the capture of a spectacular colossal squid could be a symptom of something bigger.
Kathy Marks reports
Published: 23 February 2007
It is one of the most mysterious creatures of the deep ocean, and one of the
most elusive. Only half a dozen colossal squid have been caught. The specimen hauled out of the inky waters of Antarctica is believed to be the biggest, weighing half a ton, with eyes as big as dinner plates.
The gigantic sea creature, about 39ft long, with a large beak and razor-sharp hooks on the end of its tentacles, was feasting on a Patagonian toothfish - itself one of the more sizeable members of the marine population - when it was caught by New Zealand fishermen this month.
Experts described it yesterday as a "phenomenal" find. One said that if calamari rings were made from it, they would be the size of tractor tyres.
Colossal squid, or Mesonychoteuthis hamiltoni, are not related to giant squid, which grow to a maximum of "only" 39ft and are somewhat lighter. The biggest colossal squid are believed to reach 46ft in length. They are active and aggressive killers that have been known to attack sperm whales, and they live at depths of up to 6,500ft.
The New Zealand Fisheries Minister, Jim Anderton, who announced the discovery of the new specimen, said it took fishermen two hours to land it. They had been fishing with long lines for Patagonian toothfish, also known as Chilean sea bass, in the Southern Ocean. Mr Anderton said "the squid was eating a hooked toothfish when it was hauled from the deep".
The crew stopped long lining and manoeuvred the squid into a cargo net to haul it on board their ship, San Aspiring. It was then frozen in the ship's hull and brought back to New Zealand for scientific analysis. Experts have yet to examine it, but they believe it to be the first intact adult male ever landed.
The species was first recorded in 1925, when two arms were found in the stomach of a sperm whale. In 1981, a Russian trawler caught a 13ft immature female in its net in Antarctic waters. Another complete specimen was captured near the surface in 2003. But so few adults have been seen that scientists know next to nothing about the colossal squid's life history, diet, behaviour and reproductive patterns.
If initial estimates are correct, the 990lb creature that is on its way to New Zealand's national museum in Wellington, Te Papa, is 330lb bigger than an immature female caught on the surface of the Ross Sea, off the Antarctic.
Steve O'Shea, a squid expert at Auckland University of Technology, said that the new specimen eclipsed that find. "I can assure you that this is going to draw phenomenal interest," he said. "It is truly amazing."
Mr Anderton predicted that marine scientists "will be very interested in this amazing creature, as it adds immeasurably to our understanding of the marine environment".
He said: "The squid was almost dead when it reached the surface, and the careful work of the crew was paramount in getting this specimen aboard in good condition." The creature would be photographed, measured, tissue sampled, registered, and preserved intact for scientific study, he added. "Ongoing examination of this giant will help to unlock some of the mysteries of the deep ocean. Even basic questions such as how large does this species grow to, and how long does it live for are not yet known."
While colossal squid live in freezing Antarctic waters, giant squid, or Architeuthis dux, are found around the coast of New Zealand. Dr O'Shea has described colossal squid as "not just larger, but an order of magnitude meaner". He told the BBC: "It really has to be one of the most frightening predators out there. It's without parallel in the oceans."
While the giant squid has suckers lined with small teeth on the end of its tentacles, the colossal squid has two rows of rotating sharp hooks, as well as a large beak - a lethal combination. It is believed to eat marine worms, Patagonian toothfish, which themselves reach up to 8ft long, and smaller squid. It finds its prey by lighting up the dark waters.
Large numbers of sperm whales have been found with scars on their backs, thought to have been caused by the hooks of colossal squid. But the sperm whale is one creature that is larger and more fearsome.
The majority of partial colossal squid specimens, along with a sizeable number of beaks, have been found inside sperm whales' stomachs. Encounters between these two gigantic creatures are believed to result in battles of epic proportions. Colossal squid have eight "arms" and two tentacles, and are the largest known invertebrate. Their protruding eyes are believed to be the biggest in the animal kingdom. The discovery of the first intact adult male may shed light on how these mammoths of the deep reproduce. The males are believed to have something resembling a penis.
Some speculate that colossal and giant squid fuelled the sea monster legends that date back to the 12th century, when Norwegian seafarers returned with stories of a formidable creature called a Kraken. According to National Geographic magazine, the Bishop of Bergen in the 18th century compared the Kraken with a "floating island" with massive arms. "It is said, if they were to lay hold of the largest man-of-war, they would pull it down to the bottom," he wrote.
The Jules Verne's novel Twenty Thousand Leagues Under the Sea featured a "squid of colossal dimensions", supposedly based on a true encounter between a giant squid and a French naval vessel. Sailors during the Second World War described being attacked by a giant squid when their ship sunk, and even claimed that one of their number was eaten.
Yet while stories of giant man-eating squid have terrified sailors and entertained children alike through the ages, there is growing evidence to suggest that even normal squid are becoming gradually larger thanks to rising sea temperatures.
It may well be one of the few positive effects of global warming: for those who enjoy meaty calimari, recent research suggests that while rising sea temperatures can have a catastrophic effect on many species of fish, squid and octopuses become bigger in warmer waters.
Scientists in Australia discovered five years ago that the breeding cycle and growth rate of squid is directly related to the temperature of the sea. A 1 per cent increase in the temperature of the water where they reproduce and feed can cause juvenile squid to double their size. The reason for such colossal growth, scientists believe, is because the animals' digestive enzymes work faster in warmer waters.
Similarly large squid have been found by American researchers in Alaska and Siberia where sea temperatures have risen by as much as 4C.
"The good news is they taste great," says John Forsythe, an expert on Cephalopods, the biological family to which squid belong. "They're pure protein and they have no bones."
Mysterious inhabitants of the oceans' murky depths
Little is known about the lives of the large species of squid - giant and colossal - that live in the deep ocean except that they must inhabit an exceptionally dark environment.
Sightings of dead squid floating on the sea surface or washed up on beaches have been occasionally reported over the years but none have been captured alive.
They are thought to be fast swimmers and either hunt or scavange smaller fish and crustaceans. They are also probably the source of the many ancient myths about ship-swallowing monsters of the deep. As coastal waters have been depleted of fish stocks, fishing vessels have been going further out to the deeper ocean to catch more exotic species for the table, such as the Patagonian tooth fish, more commonly known as the Chilean sea bass.
Deep-sea fishing has probably led to an increase in the number of giant and colossal squid being caught as accidental by-catch in nets, said Alex Rogers, a marine biologist at the London Zoo. "They are very fast moving and the live in the deep ocean so it's very difficult to study them. They can probably see quite well even in dim light because things are lit up by bio-fluorescence at this depth, so it's surprising that this one was caught in a net," Dr Rogers said.
Many of the species in the deep ocean are slow-growing and take many years to reach sexual maturity. Some fish can live for more than 150 years, but nobody knows how long a colossal or giant squid can live.
Jon Ablett of the Natural History Museum in London said that DNA samples will be quickly taken from the colossal specimen. The animal will then be preserved in a formalin solution. "It's very exciting because this is the first time we have been able to study a complete, mature adult," Mr Ablett said.
The deep sea is considered the last great wilderness on the planet. Many unique lifeforms have evolved to cope with the high pressures, constant cold and total darkness of the depths.
Steve Connor
Kathy Marks reports
Published: 23 February 2007
It is one of the most mysterious creatures of the deep ocean, and one of the
most elusive. Only half a dozen colossal squid have been caught. The specimen hauled out of the inky waters of Antarctica is believed to be the biggest, weighing half a ton, with eyes as big as dinner plates.The gigantic sea creature, about 39ft long, with a large beak and razor-sharp hooks on the end of its tentacles, was feasting on a Patagonian toothfish - itself one of the more sizeable members of the marine population - when it was caught by New Zealand fishermen this month.
Experts described it yesterday as a "phenomenal" find. One said that if calamari rings were made from it, they would be the size of tractor tyres.
Colossal squid, or Mesonychoteuthis hamiltoni, are not related to giant squid, which grow to a maximum of "only" 39ft and are somewhat lighter. The biggest colossal squid are believed to reach 46ft in length. They are active and aggressive killers that have been known to attack sperm whales, and they live at depths of up to 6,500ft.
The New Zealand Fisheries Minister, Jim Anderton, who announced the discovery of the new specimen, said it took fishermen two hours to land it. They had been fishing with long lines for Patagonian toothfish, also known as Chilean sea bass, in the Southern Ocean. Mr Anderton said "the squid was eating a hooked toothfish when it was hauled from the deep".
The crew stopped long lining and manoeuvred the squid into a cargo net to haul it on board their ship, San Aspiring. It was then frozen in the ship's hull and brought back to New Zealand for scientific analysis. Experts have yet to examine it, but they believe it to be the first intact adult male ever landed.
The species was first recorded in 1925, when two arms were found in the stomach of a sperm whale. In 1981, a Russian trawler caught a 13ft immature female in its net in Antarctic waters. Another complete specimen was captured near the surface in 2003. But so few adults have been seen that scientists know next to nothing about the colossal squid's life history, diet, behaviour and reproductive patterns.
If initial estimates are correct, the 990lb creature that is on its way to New Zealand's national museum in Wellington, Te Papa, is 330lb bigger than an immature female caught on the surface of the Ross Sea, off the Antarctic.
Steve O'Shea, a squid expert at Auckland University of Technology, said that the new specimen eclipsed that find. "I can assure you that this is going to draw phenomenal interest," he said. "It is truly amazing."
Mr Anderton predicted that marine scientists "will be very interested in this amazing creature, as it adds immeasurably to our understanding of the marine environment".He said: "The squid was almost dead when it reached the surface, and the careful work of the crew was paramount in getting this specimen aboard in good condition." The creature would be photographed, measured, tissue sampled, registered, and preserved intact for scientific study, he added. "Ongoing examination of this giant will help to unlock some of the mysteries of the deep ocean. Even basic questions such as how large does this species grow to, and how long does it live for are not yet known."
While colossal squid live in freezing Antarctic waters, giant squid, or Architeuthis dux, are found around the coast of New Zealand. Dr O'Shea has described colossal squid as "not just larger, but an order of magnitude meaner". He told the BBC: "It really has to be one of the most frightening predators out there. It's without parallel in the oceans."
While the giant squid has suckers lined with small teeth on the end of its tentacles, the colossal squid has two rows of rotating sharp hooks, as well as a large beak - a lethal combination. It is believed to eat marine worms, Patagonian toothfish, which themselves reach up to 8ft long, and smaller squid. It finds its prey by lighting up the dark waters.
Large numbers of sperm whales have been found with scars on their backs, thought to have been caused by the hooks of colossal squid. But the sperm whale is one creature that is larger and more fearsome.
The majority of partial colossal squid specimens, along with a sizeable number of beaks, have been found inside sperm whales' stomachs. Encounters between these two gigantic creatures are believed to result in battles of epic proportions. Colossal squid have eight "arms" and two tentacles, and are the largest known invertebrate. Their protruding eyes are believed to be the biggest in the animal kingdom. The discovery of the first intact adult male may shed light on how these mammoths of the deep reproduce. The males are believed to have something resembling a penis.
Some speculate that colossal and giant squid fuelled the sea monster legends that date back to the 12th century, when Norwegian seafarers returned with stories of a formidable creature called a Kraken. According to National Geographic magazine, the Bishop of Bergen in the 18th century compared the Kraken with a "floating island" with massive arms. "It is said, if they were to lay hold of the largest man-of-war, they would pull it down to the bottom," he wrote.
The Jules Verne's novel Twenty Thousand Leagues Under the Sea featured a "squid of colossal dimensions", supposedly based on a true encounter between a giant squid and a French naval vessel. Sailors during the Second World War described being attacked by a giant squid when their ship sunk, and even claimed that one of their number was eaten.
Yet while stories of giant man-eating squid have terrified sailors and entertained children alike through the ages, there is growing evidence to suggest that even normal squid are becoming gradually larger thanks to rising sea temperatures.
It may well be one of the few positive effects of global warming: for those who enjoy meaty calimari, recent research suggests that while rising sea temperatures can have a catastrophic effect on many species of fish, squid and octopuses become bigger in warmer waters.
Scientists in Australia discovered five years ago that the breeding cycle and growth rate of squid is directly related to the temperature of the sea. A 1 per cent increase in the temperature of the water where they reproduce and feed can cause juvenile squid to double their size. The reason for such colossal growth, scientists believe, is because the animals' digestive enzymes work faster in warmer waters.
Similarly large squid have been found by American researchers in Alaska and Siberia where sea temperatures have risen by as much as 4C.
"The good news is they taste great," says John Forsythe, an expert on Cephalopods, the biological family to which squid belong. "They're pure protein and they have no bones."
Mysterious inhabitants of the oceans' murky depths
Little is known about the lives of the large species of squid - giant and colossal - that live in the deep ocean except that they must inhabit an exceptionally dark environment.
Sightings of dead squid floating on the sea surface or washed up on beaches have been occasionally reported over the years but none have been captured alive.
They are thought to be fast swimmers and either hunt or scavange smaller fish and crustaceans. They are also probably the source of the many ancient myths about ship-swallowing monsters of the deep. As coastal waters have been depleted of fish stocks, fishing vessels have been going further out to the deeper ocean to catch more exotic species for the table, such as the Patagonian tooth fish, more commonly known as the Chilean sea bass.
Deep-sea fishing has probably led to an increase in the number of giant and colossal squid being caught as accidental by-catch in nets, said Alex Rogers, a marine biologist at the London Zoo. "They are very fast moving and the live in the deep ocean so it's very difficult to study them. They can probably see quite well even in dim light because things are lit up by bio-fluorescence at this depth, so it's surprising that this one was caught in a net," Dr Rogers said.
Many of the species in the deep ocean are slow-growing and take many years to reach sexual maturity. Some fish can live for more than 150 years, but nobody knows how long a colossal or giant squid can live.
Jon Ablett of the Natural History Museum in London said that DNA samples will be quickly taken from the colossal specimen. The animal will then be preserved in a formalin solution. "It's very exciting because this is the first time we have been able to study a complete, mature adult," Mr Ablett said.
The deep sea is considered the last great wilderness on the planet. Many unique lifeforms have evolved to cope with the high pressures, constant cold and total darkness of the depths.
Steve Connor
Subscribe to:
Posts (Atom)
