|Welcome to Carnivora. We hope you enjoy your visit.|
You're currently viewing our forum as a guest. This means you are limited to certain areas of the board and there are some features you can't use. If you join our community, you'll be able to access member-only sections, and use many member-only features such as customizing your profile, sending personal messages, and voting in polls. Registration is simple, fast, and completely free.
Join our community!
If you're already a member please log in to your account to access all of our features:
|Blue Whale - Balaenoptera musculus|
|Topic Started: Jan 9 2012, 12:32 PM (1,601 Views)|
|Taipan||Jan 9 2012, 12:32 PM Post #1|
Blue Whale - Balaenoptera musculus
Species: Balaenoptera musculus
The Blue Whale (Balaenoptera musculus) is a marine mammal belonging to the suborder of baleen whales. At up to 33 meters (110 feet) in length and 181 metric tonnes (200 short tons) or more in weight, it is believed to be the largest animal to have ever lived on Earth, though some recent dinosaur discoveries may contradict this long-held belief.
Blue Whales were abundant in most oceans around the world until the beginning of the twentieth century. For the first 40 years of that century they were hunted by whalers almost to extinction. Hunting of the species was outlawed by the international community in 1966. A 2002 report estimated there were 5,000 to 12,000 Blue Whales worldwide located in at least five groups. More recent research into the Pygmy subspecies suggest this may be an under-estimate. Before whaling the largest population 239,000 (range 202,000 to 311,000) was in the Antarctic but now there remain only much smaller (around 2,000) concentrations in each of the North-East Pacific, the Antarctic, and the Indian Ocean. There are two more groups in the North Atlantic and at least two in the Southern Hemisphere.
Taxonomy and evolution
Blue Whales are rorquals (family Balaenopteridae), a family that includes the Humpback Whale, the Fin Whale, the Bryde's Whale, the Sei Whale and the Minke Whale. The family Balaenopteridae is believed to have diverged from the other families of the suborder Mysticeti as long ago as the middle Oligocene. However, it is not known when the members of these families diverged from each other. The Blue Whale is usually classified as one of seven species of whale in the genus Balaenoptera; however, DNA sequencing analysis indicates that Blue Whales are phylogenetically closer to the Humpback (Megaptera) and the Gray Whale (Eschrichtius) than to other Balaenoptera species; should further research corroborate these relationships, it will be necessary to recognize the separate genus Sibbaldus for the Blue Whale.
A phylogenetic tree of animals related to the Blue WhaleThere have been at least 11 documented cases of Blue/Fin Whale hybrid adults in the wild. Aranson and Gullberg (1983) describe the genetic distance between a Blue and a Fin as about the same as that between a human and gorilla. Blue Whale/Humpback Whale hybrids are also known.
The specific name musculus is Latin and could mean "muscular", but it can also be interpreted as "little mouse". Linnaeus, who named the species in his seminal work of 1758, would have known this and, given his sense of humour, may have intended the ironic double meaning. Other common names for the Blue Whale have included the Sulphur-bottom, Sibbald's Rorqual, the Great Blue Whale and the Great Northern Rorqual. These names have fallen into disuse in recent decades.
Authorities classify the species into three subspecies: B. m. musculus, consisting of the north Atlantic and north Pacific populations, B. m. intermedia, the Southern Ocean population and B. m. brevicauda (also known as the Pygmy Blue Whale) found in the Indian Ocean and South Pacific. Some older authorities also list B. m. indica as a further separate subspecies in the Indian Ocean, but it is most likely that these blue whales are pygmy blue whales, and this designation does not therefore have a listing in the Red List of Threatened Species. While both subdivisions are still questioned by some scientists; other scientists have suggested that South-East Pacific blue whales may also be separate subspecies.
The Blue Whale has a long tapering body that appears stretched in comparison with the much stockier appearance of other whales. The head is flat and U-shaped and has a very prominent ridge running from the blowhole to the top of the upper lips. The front part of the mouth is thick with baleen plates; around 300 plates (each one metre long) hang from the upper jaw, running half a metre back into the mouth. Between 60 and 90 grooves (called ventral pleats) run along the throat parallel to the body. These plates assist with evacuating water from the mouth after lunge feeding (see feeding below).
The dorsal fin is small, visible only briefly during the dive sequence. It varies in shape from one individual to another; some only have a barely perceptible lump, but other whales' dorsal fins are quite prominent and falcate. It is located around three-quarters of the way along the length of the body. When surfacing to breathe, the Blue Whale raises its shoulder and blow hole region out of the water to a greater extent than other large whales (such as the Fin or Sei). This can often be a useful clue to identifying a species at sea. When breathing, the whale emits a spectacular vertical single column blow (up to 12 m, typically 9 m) that can be seen from many kilometers on a calm day. Its lung capacity is 5,000 litres.
The blow of a Blue Whale
The small dorsal fin of this Blue Whale is just visible
The flippers are three to four metres long. The upper side is grey with a thin white border. The lower side is white. The head and tail fluke are generally uniformly grey coloured. The back, and sometimes the flippers, are usually mottled. The degree of mottling varies substantially from individual to individual. Some may have a uniform grey colour all over, but others demonstrate a considerable variation of dark blues, greys and blacks all tightly mottled.
Blue Whales can reach speeds of 50 km/h (30 mph) over short bursts, usually when interacting with other whales, but 20 km/h (12 mph) is a more typical travelling speed. When feeding they slow down to 5 km/h (3 mph). Some Blues in the North Atlantic and North Pacific raise their tail fluke when diving. The majority, however, do not.
Blue Whales most commonly live alone or with one other individual. It is not known whether those that travel in pairs stay together over many years or form more loose relationships. In areas of very high food concentration, as many as 50 Blue Whales have been seen scattered over a small area. However, they do not form large close-knit groups as seen in other baleen species.
The Blue Whale is believed to be the largest animal ever to have lived on Earth. The largest known dinosaur of the Mesozoic era was the Argentinosaurus, which is estimated to have weighed up to 90 tonnes (100 short tons). There is some uncertainty about the biggest Blue Whale ever found. Most data comes from Blue Whales killed in Antarctic waters during the first half of the twentieth century and was collected by whalers not well-versed in standard zoological measurement techniques. The longest whales ever recorded were two females measuring 33.6 m and 33.3 m (110 ft 3 in and 109 ft 3 in) respectively. However, there are some disputes over the reliability of these measurements. The longest whale measured by scientists at the American National Marine Mammal Laboratory (NMML) was 29.9 m long (98 ft) — about the same length as a Boeing 737 aeroplane or three double-decker buses.
A Blue Whale's tongue is about the size of an elephant and 50 humans could stand in its mouth: although the mouth is as large as a small garage, the dimensions of its throat are such that a blue whale cannot swallow an object wider than a beach ball . Its heart is close to the size of a small car and is the largest known in any animal. A human baby could squeeze into a Blue Whale's aorta, which is about 23 centimetres (9 inches) in diameter. During the first 7 months of its life, a Blue Whale calf drinks approximately 400 litres (100 US gallons) of milk every day. Blue Whale calves gain weight as quickly as 90 kg (200 pounds) every 24 hours. Even at birth, they weigh up to 2700 kg (6000 lb) – the same as a fully-grown hippopotamus.
Blue Whales are very difficult to weigh because of their massive size. Most Blue Whales killed by whalers were not weighed as a whole, but cut up into manageable pieces before being weighed. This caused an underestimate of the total weight of the whale, due to loss of blood and other fluids. Nevertheless, measurements between 150 and 170 tonnes (160 and 190 short tons) were recorded of animals up to 27 m (88 ft 6 inches) in length. The weight of a 30 m (98 ft) individual is believed by the NMML to be in excess of 180 tonnes (200 short tons). The largest Blue Whale accurately weighed by NMML scientists to date was a female that weighed 177 tonnes (196 short tons).
A juvenile Blue Whale with its motherMating starts in late autumn, and continues to the end of winter. Little is known about mating behaviour or even breeding grounds. Females typically give birth at the start of the winter once every two to three years after a gestation period of ten to twelve months. The calf weighs about two and a half tonnes and is around 7 m in length. Weaning takes place for about six months, by which time the calf has doubled in length. Sexual maturity is typically reached at eight to ten years by which time males are at least 20 m long (or more in the southern hemisphere). Females are larger still, reaching sexual maturity at around the age of five, by which time females are about 21 m long.
Scientists estimate that Blue Whales can live for at least eighty years; however, since individual records do not date back into the whaling era, this will not be known with certainty for many years yet. The longest recorded study of a single individual is thirty-four years, in the north-east Pacific (reported in Sears, 1998). The whales' only natural predator is the Orca. Calambokidis et al (1990) report that as many as 25% of mature Blue Whales have scars resulting from Orca attack. The rate of mortality due to such attacks is unknown.
Blue Whale strandings are extremely uncommon and, because of the species' social structure, mass strandings are unheard of. However when strandings do occur they can become quite a public event. In 1920, a Blue Whale washed up near Bragar on the Isle of Lewis in the Outer Hebrides of Scotland. It had been shot in the head by whalers, but the harthingy had failed to explode. As with other mammals, the fundamental instinct of the whale was to try to carry on breathing at all costs, even though this meant beaching to prevent itself from drowning. Two of the whale's bones were erected just off a main road on Lewis, and remain a tourist attraction.
The Blue Whale is the loudest animal in the world. Estimates made by Cummings and Thompson (1971) and Richardson et al (1995) suggest that source level of sounds made by Blue Whales are between 155 and 188 decibels when measured at a reference pressure of one micropascal at one metre. By comparison, a pneumatic drill is about 100 dB. A human, however, would likely not perceive the Blue Whale as the loudest of all animals. All Blue Whale groups make calls at a fundamental frequency of between 10 and 40 Hz, and the lowest frequency sound a human can typically perceive is 20 Hz. Blue Whale calls last between ten and thirty seconds. Additionally Blue Whales off the coast of Sri Lanka have been recorded repeatedly making "songs" of four notes duration lasting about two minutes each, reminiscent of the well-known Humpback Whale songs. Researchers believe that as this phenomenon has not been seen in any other populations, it may be unique to the B. m. brevicauda (Pygmy) subspecies.
The hunting era
Blue Whales are not easy to catch, kill, or retain. Their speed and power meant that they were rarely targeted by early whalers who instead targeted Sperm and Right Whales. As the populations of these other species declined, whalers increasingly hunted the largest baleen whales, including the Blue Whale. In 1864 Norwegian Svend Foyn equipped a steamboat with harthingys specifically designed for catching large whales. Although initially cumbersome and with a low success rate, the harthingy became the weapon of choice for whale hunting, and by the end of the nineteenth century, the population of Blue Whales in the North Atlantic had declined significantly.
Hunting of Blue Whales rapidly increased around the world, and by 1925, the United States, Britain and Japan had joined Norway in chasing whales on 'catcher boats' that caught the whales and handed them onto huge 'factory ships' for processing. In 1930/1931, these ships killed 29,400 Blue Whales in the Antarctic alone. By the end of World War II populations had been significantly depleted, and in 1946 the first quotas restricting international trade in whales were introduced. These were ineffective because of the lack of differentiation between species. Rare species could be hunted equally with those found in relative abundance. Blue Whale hunting was finally banned in the 1960s by the International Whaling Commission, and illegal USSR whaling halted in the 1970s. 330,000 Blue Whales had been killed in the Antarctic, 33,000 in the rest of the Southern Hemisphere, 8,200 in the North Pacific, and 7,000 in the North Atlantic. The largest original population, in the Antarctic, had been reduced to 0.15% of their original numbers .
The whale hunters had clearly depleted their stocks to exhaustion, and instead of a long term steady small harvest had chosen to nearly exterminate the population. In total over a long time span they would have far fewer whales catches than they would have if the hunting had been carried out according to marine biologist monitoring of the population. The hunting of long lived mammals worked according to different principles than that for short lived fish so the stocks of whales would be depleted for a very long time period.
Population and distribution today
A Blue Whale set against the backdrop of the AzoresSince the whaling ban, it is not well known whether the global Blue Whale population is increasing or remaining stable. In the Antarctic, best estimates show a significant increase at 7.3% per year since the end of illegal Soviet Union whaling, but numbers remain at under 1% of their original levels. It has also been suggested that Icelandic and California populations are increasing but these increases are not statistically significant. The total world population was estimated to be between 5,000 and 12,000 in 2002 although there is great uncertainty in available estimates for many areas. The Blue Whale remains listed as "endangered" on the IUCN Red List of threatened species as it has been since the list's inception. The largest known concentration, consisting of about 2,000 individuals, is the North-East Pacific population that ranges from Alaska to Costa Rica but is most commonly seen from California in summer. Sometimes this population strays over to the North-West Pacific; infrequent sightings between Kamchatka and the northern tip of Japan have been recorded.
In the Southern Hemisphere, there appear to be two distinct subspecies, the Antarctic blue whale and the poorly-understood Pygmy blue whale, found in Indian Ocean waters. Recent abundance estimates for the Antarctic subspecies range from 1100 to 1700. Research into the number of Pygmy Blues is on-going. Estimates from a 1996 survey were that 424 pygmy blue whales were in a small area south of Madagascar alone, thus it is likely that numbers in the entire Indian Ocean are in the thousands or more. If this is true, the global numbers are much higher.
Migratory patterns of these subspecies are not well known. For example, pygmy blue whales have been recorded in the northern Indian Ocean (Oman, Maldives, Sri Lanka) where they may form a distinct resident population. In addition, the population of Blue Whales occurring off Chile and Peru may also be a distinct population. Some Antarctic blue whales approach the eastern South Atlantic coast in winter, and occasionally their sounds are heard off Peru, Western Australia, and in the northern Indian Ocean. In Chile, the Cetacean Conservation Center, with support from the Chilean Navy, is undertaking extensive research and conservation work on a recently discovered feeding aggregation of the species off the coast of Chiloe Island.
In the North Atlantic, two stocks are recognized. The first is found off Greenland, Newfoundland, Nova Scotia and the Gulf of Saint Lawrence. This group is estimated to total about 500. The second, more eastern group is spotted from the Açores in Spring to Iceland in July and August; it is presumed that the whales follow the Mid-Atlantic Ridge between the two volcanic islands. Beyond Iceland, Blue Whales have been spotted as far north as Spitsbergen and Jan Mayen though such sightings are rare. Scientists do not know where these whales spend their winters. The total North Atlantic population is between 600 and 1500.
Human threats to the potential recovery of Blue Whale populations include the accumulation of polychlorinated biphenyl (PCB) chemicals within the whale's blood, causing poisoning and premature death, and the ever-increasing amount of noise created by ocean traffic. This noise drowns out the noises produced by whales, which may make it harder for whales to find a mate.
Efforts to calculate the Blue Whale population more accurately are supported by marine mammologists at Duke University who maintain the OBIS-SEAMAP (Ocean Biogeographic Information System - Spatial Ecological Analysis of Megavertebrate Populations), a collation of marine mammal sighting data from around 130 sources.
|Taipan||Jan 11 2012, 10:06 PM Post #2|
Blue whale carcass washes up on beach near Ventura
The cause of death is unknown, but scientists are eager to examine it. Ventura County plans to tow it through the water to another beach today.
By Steve Chawkins and Kenneth R. Weiss, Los Angeles Times Staff Writers
September 15, 2007
The 70-foot carcass of a blue whale rests on the shore at Hobson Beach Park north of Ventura. The whales have been migrating through the Santa Barbara Channel.
Beached beside a highway 10 miles up the coast from Ventura, the immense carcass of a blue whale drew hundreds of spectators Friday as biologists began to delve into it for a rare, clinical glimpse of the world's largest animal.
Nobody yet knows what killed the whale, which is about 78 feet long and estimated to weigh around 100,000 pounds. But scientists are eager to do detailed examinations of the putrefying hulk, which washed ashore Thursday night just yards from Hobson County Park, a seaside campground off Pacific Coast Highway.
Ventura County officials planned to have the massive body towed about a mile through the water this morning to a beach with better access for heavy equipment and more sand for burying remains. The beach, just up the coast from Faria County Park, fronts a popular RV parking area, which will have to be partially cleared as scientists do their grim studies.
"There will be some unhappy campers, as they say," said Ron Van Dyck, a county parks official.
The cause of the whale's death won't be known until scientists study tissue samples.
It wasn't the only blue whale death in recent days. Last weekend, a lifeless blue whale was found floating in Long Beach Harbor -- possibly hauled there inadvertently by a freighter that struck it in the Santa Barbara Channel, according to Joe Cordaro, a wildlife biologist with the National Marine Fisheries Service.
On Wednesday, Seaman Eti Lotoa, standing watch on the U.S. Navy frigate Curts while on a training mission, sighted what may be another dead blue whale in the water 70 miles from San Diego -- but it also might be the carcass of the Long Beach whale, which was towed to sea by the Coast Guard, Cordaro said.
In Ventura County on Friday, lookie-loos parked by the roadside to take photos of the dead whale and give their children an up-close, if somber, look at a colossal example of an endangered species. An Amtrak train stopped on tracks across the road as the engineer took a photo with his cellphone and passengers goggled out the windows.
"Amazing!" said Terry Hewitt, a cook at Cal State Channel Islands who came to view the whale on her day off. "I was swimming out there yesterday and if that thing had passed me in the water -- well, oh my God!"
Authorities had been tracking the carcass for a couple of days before it came ashore. They estimated its weight at 50 tons.
About 100 to 200 blue whales have been feeding in the Santa Barbara Channel during their annual summer migration from Mexico and Central America. This one was spotted from the air Tuesday, floating, and scientists tagging healthy blue whales were directed to it.
"There was no obvious sign of trauma," Bruce Mate, director of the Marine Mammal Institute at Oregon State University, said early Friday. Later, after a layer of blubber was stripped off, the whale appeared to have a massive bruise on its side.
"Even when there's a collision, the situation is cryptic," said Mate, adding that Frances Gulland, the director of veterinary science at the Marine Mammal Center in Sausalito, Calif., was brought to the scene for her expertise in deciphering the cause of cetacean deaths.
Gulland, a rock climber by avocation, hoisted herself up the carcass using knives like climbers' pitons. After examining the uncovered bruise, she offered a tentative conclusion to the gathered scientists.
"I have a diagnosis," she said. "It got thwacked on its side. There's only one thing that could do that -- a ship." However, that conclusion will remain tentative until scientists can check for broken bones and other signs of trauma.
Although about 3,000 of the world's 12,000 blue whales are thought to swim off the West Coast of the Americas, they seldom wash ashore. When they do, scientists scramble for the chance to "learn more about their basic biology and establish baseline data for the species," said Paul Collins, curator of vertebrate zoology for the Santa Barbara Museum of Natural History.
In a baseball cap and jeans, Collins was at the scene Friday, watching as the whale's body, embedded in the sand, was rolled gently by the waves breaking around it. He and other scientists were preparing for a necropsy on the animal -- a complicated procedure that entails taking at least 35 measurements, cutting holes in the carcass and extracting tissue samples, bodily fluids and stomach contents.
Marine researchers examine the 70-foot carcass of a blue whale at Hobson Beach Park north of Ventura. The whales have been migrating through the Santa Barbara Channel.
He said the work would take days and might involve the use of heavy equipment to peel back thick layers of blubber. When the lab tests are completed, Collins said, scientists could have crucial information on the animal's death -- such as whether domoic acid, a substance produced by algae and implicated in die-offs of seabirds and sea lions, might be to blame.
When whales wash ashore, the owner of the coastline where they beach is responsible for dealing with their remains after scientific examination, said Cordaro, the National Marine Fisheries biologist.
On Friday, Ventura County officials briefly considered towing the whale to the broad expanse of sand at Port Hueneme, about 20 miles down the coast. However, they abandoned the plan because a towboat would run afoul of the law by hauling the carcass through shipping lanes.
The whale's skeleton may be dismantled and shipped to a museum or university. Oregon State and the Santa Barbara Museum of Natural History have expressed interest.
If it goes to Santa Barbara, it would be the museum's second blue whale. Five have been beached since 1980 in Santa Barbara, San Luis Obispo and Ventura counties, said Collins, the museum curator. The skeleton of one that came ashore at the base of a 100-foot cliff at Vandenberg Air Force Base was winched up, bone by bone, and in a two-year process, cleaned and reassembled outside the museum.
A distinctive presence, the skeleton has been the backdrop for photos of countless children over the years.
"It's become something of an icon," Collins said.
Frances Gulland, director of veterinary science at the Marine Mammal Center, removes blubber from the whale, which may have been struck by a ship.
|Taipan||Jan 11 2012, 10:07 PM Post #3|
Newborn Blue Whale Caught on Film -- A First
March 4, 2009—For the first time, a newborn blue whale (shown with photographer) has been captured on camera, according to a National Geographic documentary to air Sunday (video clip from the show below).
The baby is believed to be the first proof that a blue whale hot spot in the Pacific Ocean is a birthing ground for the endangered species.
During a January 2008 expedition to the "Dome"—a warm-water region off Costa Rica that draws blue whales from hundreds of miles away—the researchers had begun to lose hope of finding a calf. Then two telltale spouts began erupting at the sea surface.
"Oh, tell me that one of them is a small blow, please," Bruce Mate, of the Marine Mammal Institute at Oregon State University, says in the documentary.
One of the spouts did turn out to be that of a calf, which approached the research boat—surprising the scientists, given blue whale mothers' protective reputations.
A photographer and videographer dived in and soon had the visual evidence needed: fetal folds establishing the whale as a newborn blue.
Averaging 25 feet (7.6 meters) long at birth, blue whale babies nurse for about seven months until they double in size. Gaining about 200 pounds (90 kilograms) a day, they are the biggest babies ever known to have roamed the Earth.
Blue whales were heavily hunted until a worldwide ban in 1966. Today they are listed as endangered by the International Union for Conservation of Nature, meaning they face a very high risk of extinction in the wild.
By comparing new and old photos of blue whale spot patterns—which can be as distinct, in their way, as human fingerprints—expedition member John Calambokidis later identified the Dome mother as a summer resident of California's Channel Islands. The researchers speculate that mother and baby returned to the islands, rich with krill but fraught with danger from increasing shipping traffic.
The destinations of other whales at the Dome remain a mystery—unfortunately for conservationists looking to safeguard blue whale migration routes.
On a previous trip, researchers had found that more than 75 percent of the whales at the Dome were from the U.S. West Coast. But the recent expedition found only 25 percent.
"It caught us by surprise," Calambokidis told National Geographic News. A whale expert from the Cascadia Research Collective in Washington State, Calambokidis has received funding from National Geographic's Committee for Research and Exploration. (The National Geographic Society owns National Geographic News.)
The Dome's significance to blue whale breeding, though, is no longer in question.
"We're quite confident now that this is one of the very, very important areas for blue whales in the entire world," Mate said.
|Taipan||Jan 11 2012, 10:07 PM Post #4|
Blue Whales Re-establishing Former Migration Patterns
ScienceDaily (May 12, 2009) — The planet’s largest animal may be returning to pre-whaling feeding grounds. Scientists have documented the first known migration of blue whales from the coast of California to areas off British Columbia and the Gulf of Alaska since the end of commercial whaling in 1965.
In the scientific journal Marine Mammal Science, researchers from Cascadia Research Collective in Washington state, NOAA’s Southwest Fisheries Science Center in California, and Canada’s Department of Fisheries and Oceans identified 15 separate cases where blue whales were seen off British Columbia and the Gulf of Alaska. Four of the whales were identified as animals previously observed off the coast of California, suggesting a re-establishment of a historical migration pattern.
Researchers made this identification by comparing photographs of blue whales taken in the north Pacific Ocean since 1997 with a library of nearly two thousand photographs of blue whales off the West Coast. A positive match was determined based on pigmentation patterns in skin color and shape of the dorsal fin.
Blue whales were severely depleted during commercial whaling activities during the early 1900’s in the north Pacific and along the West Coast as far south as Baja California.
Formerly large populations of blue whales in the north Pacific never rebounded after commercial whaling ended while those animals off southern California have apparently fared much better.
Scientists are still not certain exactly why blue whales are now beginning to migrate from southern California to the north Pacific Ocean although changing ocean conditions may have shifted their primary food source of krill further north.
Blue whales are thought to be the largest animal ever to have existed on earth, reaching lengths of nearly 100 feet. They were nearly hunted to extinction throughout the world and are currently listed as endangered under the U.S. Endangered Species Act and as endangered on the red list of the International Union for the Conservation of Nature. There are an estimated 5,000 to 12,000 animals remaining today, with the largest population of approximately 2,000 off the U.S. West Coast.
A blue whale spouts off Moresby Island, British Columbia, Canada.
1.John Calambokidis, Jay Barlow, John K. B. Ford, Todd E. Chandler, Annie B. Douglas. Insights into the population structure of blue whales in the Eastern North Pacific from recent sightings and photographic identification. Marine Mammal Science, 2009; DOI: [url]10.1111/j.1748-7692.2009.00298.x[/url]
|Taipan||Jan 11 2012, 10:08 PM Post #5|
Blue Whale Beached -- Flipper to be Amputated?
October 22, 2009—The apparent victim of a ship collision, a dead 70-foot (20-meter) blue whale (pictured) washed ashore in a forbidding northern California cove this week.
Though unable to move the blue whale, scientists and students are leaping at the research opportunity, scrambling down rock faces to take tissue samples and eventually one of the 11-foot-long (3.5-meter-long) flippers.
Though relatively infrequent off California until recent years, ship collisions are "the number one human threat to blue whales," according to marine biologist Joe Cordaro of the U.S. National Marine Fisheries Service.
This week's collision, he said, marks the second time this year that a ship off California has fatally wounded a blue whale.
The world's largest animals, blue whales can grow to about a hundred feet (30 meters) long—about the length of a space shuttle. Listed as endangered by the International Union for Conservation of Nature, the whales are said to face a very high risk of extinction in the wild, largely due to heavy hunting prior to a 1966 ban.
A Shudder and, Later, a Beached Blue Whale
On Monday, Cordaro received a report from a ship mapping the seafloor for the fisheries service. The researchers had "felt a shudder underneath the ship" about 7 miles (11 kilometers) from shore.
Soon after, a whale surfaced, bleeding profusely, Cordaro said. Several hours later, the beached blue whale was spotted near the city of Fort Bragg.
Given the evidence—timing, location, a fresh propeller wound—Cordaro said, "I don't think there's any doubt" that the mapping ship is the culprit.
Blue Whale Tragedy Turned Scientific Windfall
"I'm as sorry as anybody that that animal perished," said Humboldt State University mammologist Thor Holmes (pictured above atop the whale). But to find "a fresh, female blue whale in a place that's accessible—that is amazing."
On Tuesday, Holmes and two students drove several hours to study the blue whale.
After he'd scrambled down the "scary" rock faces, he told the eager students to stay put for their own safety. "Man, I knew from the looks on their faces there was an insurrection brewing," he said. The others eventually found another, wetter way around.
On the shore, the researchers took blubber samples, which Holmes expects will shed light on the whale's pre-collision health.
"Just the fact that the whale has a good, thick blubber layer," he said, "shows it was a really, really healthy animal."
Blue Whale to Be Left in Place
The blue whale will be left on the Fort Bragg beach, the National Marine Fisheries Service's Cordaro said. Given the cove's inaccessibility to vehicles, he added, "That whale ain't going anywhere."
But researchers are planning more tests, including an amputation of one of the blue whale's flippers this week—a potential windfall for an ongoing Humboldt State study comparing the limbs of cetaceans, which include whales, dolphins, and porpoises.
The university is also sending more students to examine the rare specimen, and a dermatologist at Humboldt is hoping to secure hair follicles for study.
For Holmes, the specimen holds great scientific promise, but also serves as a painful reminder of humanity's role in the blue whale's rarity.
"The presence of that animal on the beach," he said, "is another sign that we're malefactors on this planet."
|Taipan||Jan 11 2012, 10:08 PM Post #6|
Pitch of Blue Whale Songs Is Declining Around the World, Scientists Discover
ScienceDaily (Dec. 9, 2009) — The sound level of songs blue whales sing across the vast expanses of the ocean to attract potential mates has been steadily creeping downward for the past few decades, and a scientist at Scripps Institution of Oceanography at UC San Diego and his colleagues believe the trend may be good news for the population of the endangered marine mammal.
Mark McDonald of WhaleAcoustics in Bellvue, Colo., along with John Hildebrand of Scripps Oceanography and Sarah Mesnick of NOAA Fisheries Southwest Fisheries Science Center studied blue whale song data from around the world and discovered a downward curve in the pitch, or frequency, of the songs. The decline was tracked in blue whales across the globe, from off the Southern California coast to the Indian and Southern Oceans.
"The basic style of singing is the same, the tones are there, but the animal is shifting the frequency down over time. The more recent it is, the lower the frequency the animal is singing in, and we have found that in every song we have data for," said Hildebrand, a professor of oceanography in the Marine Physical Laboratory at Scripps.
The study's results are published in the most recent issue of the journal Endangered Species Research.
The researchers examined a list of possible causes for the frequency drop-from climate change to a rise in human-produced ocean noise-and believe it may be explained by the increase of blue whale numbers following bans on commercial whaling activities.
While the function of blue whale songs is not known and scientists have much more to learn, they do know that all singers have been determined to be males and that the high-intensity, or loud, and low-frequency songs propagate long distances across the ocean. Blue whales are widely dispersed during the breeding season and it is likely that songs function to advertise which species is singing and the location of the singing whale.
In the heyday of commercial whaling, as blue whale numbers plummeted, it may have been advantageous for males to sing higher frequency songs, the researchers believe, in order to maximize their transmission distance and their ability to locate potential mates (females) or competitors (other males).
"It may be that when (blue whale) densities go up, it's not so far to get to the closest female, whereas back when they were depleted it may have been that the closest female was a long way away," said Hildebrand.
In the 1960s, when blue whale numbers were substantially reduced and recordings of the animals were first made, there may have been a tradeoff in which the male suitors chose to sing higher frequencies that were louder and heard over greater distances, Hildebrand said. In more recent years, as population sizes have increased, it may now be more advantageous for males to sing songs that are lower in frequency rather than louder.
"When they make these songs they need to use most of the air in their lungs," said Hildebrand. "It's like an opera singer that sees how long he can hold a note. The (male) songs are made to impress the females and/or other males, so I think that's how the boy blue whales are impressing the girls, or are showing off to other boys: by making a loud and long song."
The scientists say the same downward pitch phenomenon may be true in other whales such as fin and humpbacks, but the blue whale song, with a comparatively easier song to analyze, is a good springboard to study other species. Hildebrand says such knowledge about whale songs could be important in monitoring whale populations and recovery efforts.
During the study the researchers analyzed thousands of blue whale songs divided into at least 10 worldwide regions. These include the Northeast, Southwest and Northwest Pacific Ocean; the North Atlantic; the Southern Ocean near Antarctica; and the North and Southeast Indian Ocean. Blue whale songs have been recorded for the last 45 years through scientific and military applications by seafloor seismometers tracking regional earthquakes and dedicated whale acoustic recording packages.
In addition to NOAA National Marine Fisheries Service's Southwest Fisheries Science Center, Mesnick is affiliated with Scripps' Center for Marine Biodiversity and Conservation.
This research was funded by the U.S. Navy, NOAA and the National Science Foundation.
|Taipan||Jan 11 2012, 10:09 PM Post #7|
Blue Whales Align the Pitch of Their Songs With Extreme Accuracy, Study Finds
ScienceDaily (Aug. 2, 2010) — Blue whales are able to synchronize the pitch of their calls with an extremely high level of accuracy, and a very slim margin of error from call to call, according to a new study of the blue whale population in the eastern North Pacific. Results were published in the Journal of the Acoustical Society of America.
The authors suggest that the uniform pitch used by blue whale populations could allow individual whales to locate potential mates by swimming toward them or away from them.
"Blue whales in a given population have been observed to align their pitch to a common value, but we have now been able to determine just how accurately they are able to do so," said Roger Bland, professor of physics at San Francisco State University.
Bland and colleagues analyzed recordings of 4,378 blue whale songs, off the California coast, and focused on the whales' B calls -- the long, sad moan that typically forms the second half of the blue whale song that is specific to the eastern North Pacific population. They found that the whales all produce the B call at the same pitch, at a frequency of 16.02 Hz, exactly four octaves below middle C.
"We found that blue whales are capable of very fine control over the pitch of their call -- both in reproducing their call at the same pitch every time and in synchronizing their pitch with others," Bland said.
The study found a remarkably small variation in pitch from call to call. In musical terms, the half-tone change of pitch between the notes C and C Sharp is a 6 percent increase in pitch, whereas the variation observed between the blue whale's B calls was a 0.5 percent change in pitch.
The authors suggest that there may be an adaptive advantage to the whales tuning into a common pitch. "If whales are so super accurate in always calling at the exact same pitch, then it's possible that they could be able to detect tiny shifts in other whales' calls caused by the Doppler shift," Bland said. The Doppler shift is the apparent increase or decrease in pitch that is heard when the source of sound is moving toward or away from an individual, for example the change in pitch heard when a vehicle with a siren passes by.
Previous research has suggested that the blue whale song is produced only by males, and appears to be sung when the whales are traveling. "Given that blue whales can travel up to 5 meters per second, it's feasible that females could locate calling males by listening for the changes in the male's pitch," Bland said.
Underwater recordings were captured at the Pioneer Seamount Underwater Observatory, 50 miles off the California coast, over a three-month period in 2001.
The study's results are consistent with recent research suggesting that blue whales across the world have decreased their pitch over the last few decades. "We found the frequency of the B call to be 16 Hz in 2001, which fits well with the downward trending curve that has been observed in previous research."
Bland co-authored the paper with Michael D. Hoffman, a former student at SF State, and Newell Garfield, professor of geosciences and director of the Romberg Tiburon Center for Environmental Studies at SF State.
Spectrogram showing a visual representation of a blue whale song recorded by Professor Roger Bland. Whale songs consist of an A call, a series of pulses, followed by a long, low moan called the B call, both can be seen in the orange markings above. Inset: enlargement of a blue whale's B call, lasting about 15 seconds at a frequency of 16 Hz.
Michael D. Hoffman, Newell Garfield, Roger W. Bland. Frequency synchronization of blue whale calls near Pioneer Seamount. The Journal of the Acoustical Society of America, 2010; 128 (1): 490 DOI: [url]10.1121/1.3446099[/url]
|Taipan||Jan 11 2012, 10:09 PM Post #8|
|Taipan||Jan 11 2012, 10:10 PM Post #9|
Whales Swallow Half a Million Calories in Single Mouthful
By Wynne Parry, LiveScience Senior Writer
posted: 09 December 2010 07:52 am ET
A blue whale feeding. It's turned on its side, so you can see its smaller lower jaw and open mouth, illuminated by the midnight sun. Taken in Hinlopenrenna, a channel north of Svalbard.
The filter-feeding strategy of blue whales, the largest animals on Earth, may explain their enormous size, according to a study that determined a single mouthful of food can contain 457,000 calories, or 240 times as much energy as they burn when grabbing that mouthful.
Blue and some other whale species eat by taking enormous mouthfuls of water and filtering out their meals, often tiny crustaceans called krill, using plates of baleen made of keratin, a protein found in hair, fingernails and feathers. A team of researchers led by Jeremy Goldbogen, who is now at the Scripps Institution of Oceanography, calculated the efficiency of eating this way.
Their math supports the long-standing assumption that baleen whales are much more efficient feeders than their smaller relatives, the toothed whales, which hunt down individual prey. The finding is detailed today (Dec. 9) in the Journal of Experimental Biology.
Although the finding isn't a surprise, the baleen whales' efficiency is unprecedented in the animal kingdom, said study researcher Robert Shadwick, who studies animal biomechanics at the University of British Columbia.
When they take a gulp of water, they are filling their mouths with the amount of water equal to their own body mass, so there is nothing that comes close to doing that," Shadwick told LiveScience.
These whales may eat an enormous quantity of food in a single gulp, but the effort is taxing. As the animals dive, they lunge into a school of krill and their mouths open to 80 degrees and inflate like a parachute as water gushes in. This creates a drag, slowing the whale. Whales can make up to six lunges in a dive, according to the researchers.
To figure out how much energy the whales use when they dive, researchers recorded 200 dives between 2002 and 2007. Then a doctoral student, Goldbogen used recordings of the sounds whales made as they dived through the water to calculate their speed. He recruited a parachute aerodynamics expert to help work out the forces acting on the whales as they lunged. Ultimately, they calculated that the whales spent as much as 8,071 kilojoules (1,900 Calories) on a single lunge.
The researchers then measured the jaw bones of whales in museums to estimate the volume of the whales' mouths. They combined this with krill densities to determine how much energy the animals captured in one mouthful. The answer: up to 1,912,680 kilojoules (about 457,000 Calories).
"They are doing something that is energetically very expensive, but they are getting an enormous payoff," Shadwick said.
Edited by Taipan, Mar 9 2012, 04:34 PM.
|Taipan||Jan 11 2012, 10:10 PM Post #10|
|Taipan||Mar 9 2012, 04:40 PM Post #11|
Antarctic Blue Whale Set to Make Big Comeback
Jennifer Welsh, LiveScience Staff Writer
Date: 07 March 2012 Time: 05:00 PM ET
A new study has found a surprisingly high level of genetic diversity among critically endangered Antarctic blue whales, a good sign for their future.
After commercial whalers decimated their population during the 20th century, the Antarctic blue whale may be on the verge of a comeback. The first genetic analysis of the whales has found a surprisingly high level of diversity in the population.
"Fewer than 400 Antarctic blue whales were thought to have survived when this population was protected from commercial hunting in 1966," Angela Sremba, who performed the research as part of her master's degree at Oregon State University, said in a statement.
"The exploitation period, though intense, was brief in terms of years, so the whales' long life span and overlapping generations may have helped retain the diversity," Sremba said. "Some of the Antarctic blue whales that survived the genetic bottleneck may still be alive today."
Since the International Whaling Commission banned commercial hunting of the Antarctic blue whale (Balaenoptera musculus intermedia) in 1966, the subspecies has rebounded and now numbers around 2,200 individuals. The whales live in chilly waters around Antarctica and survive by eating tiny crustaceans called krill. They are related to both the subspecies that lives in the North Atlantic and Pacific oceans, called B. m. musculus, and the pygmy species (B. m. brevicauda) found in the Indian and South Pacific oceans.
"These animals are very long-lived — maybe 70 to 100 years — and they can grow to a length of more than 100 feet [more than 30 meters] and weigh more than 330,000 pounds [150 kilograms]," study researcher Scott Baker, associate director of the Marine Mammal Institute at Oregon State University, said in a statement. "There is a jawbone in a museum in South Africa that takes up most of the lobby." [Album: The World's Biggest Beasts]
The researchers analyzed the genetics of 215 Antarctic blue whale tissue samples (from 166 individuals) collected between 1990 and 2009. They specifically examined certain genetic markers to see how closely related these different individuals were, and found they weren't as related as researchers would expect from a small population — they had surprisingly high levels of genetic diversity.
Some endangered wildlife populations, such as the Florida panther, end up small and extremely inbred, which means they have high levels of relatedness between two individuals and low genetic diversity. These inbred populations have trouble breeding, because detrimental genes become abundant in the population, and this lowers their ability to have healthy offspring.
The genetic study indicates that the whales have escaped the inbred fate of the panther: Their numbers are small, but they still have high genetic diversity and don't seem to suffer from much inbreeding. That, Sremba said, may bode well for their future recovery.
"This is a poorly understood species of whales, despite its history of exploitation," Baker said. "Only now are we developing the technology to study such a small number of whales spread across such a vast habitat."
The study is published online today, March 7, in the journal PLoS ONE.
|Taipan||May 26 2012, 02:56 PM Post #12|
How whales open their huge mouths
By Victoria Gill BBC Nature
23 May 2012 Last updated at 20:22
A blue whale can consume 500,000 calories in one lunging gulp
Researchers have discovered how very large whales co-ordinate their jaw muscles and bones to take gigantic mouthfuls of prey.
For a blue whale, the largest animal that has ever existed, each mouthful can scoop up 100 tonnes of krill-filled water in less than 10 seconds.
Scientists have now found a sensory organ in whales' jaws which they say links bones and muscles to the brain, making the vast lunging gulps possible.
When a rorqual whale, such as a blue whale, senses that there is sufficient prey suspended in the water, it dives. Then at some point in that dive it opens its mouth, rotates its body and accelerates in order to force krill-laden water into its mouth
A blue whale has separate right and left lower jawbones, allowing it to expand its gape to approximately 3m in width. Pleats of skin and blubber below the mouth, extending to the belly, form a stretchy cavern to accommodate the vast volume of water
Plates of a comb-like structure called baleen (pictured), which hang from a rorqual whale's upper jaw, trap up to 500kg of small marine creatures - that is approximately 500,000 Calories in a single mouthful
Writing in the journal, lead researcher Nicholas Pyenson, from the Smithsonian Institution in Washington DC, explained that the rorqual whales he studied had "one of the most extreme feeding methods in aquatic vertebrates".
This whale-specific mouth organ seems to facilitate that.
Dr Pyenson said the structure looked like a "gelatinous mess", which could be the reason it was previously overlooked and assumed simply to be a fluid-filled joint between the two lower jaw bones.
By dissecting whale carcasses in fine detail, the researchers found that the structure was actually far more complex.
Found at the front tip of the lower jaws, the structure is laden with nerve endings. The team says that these are sensors which pick up signals from the jaw as it starts to open. Nerves from the organ then send signals to the brain, triggering the whales' dramatic and complex feeding lunge.
The study, carried out with colleagues from the University of British Columbia, was possible because the team had access to carcasses landed at a whaling station in Iceland.
The organ, pictured on the right of this image, is at the tip or "chin" of the whales' lower jaws
"We were able to work with tissue samples that were freshly dead," explained Dr Pyenson. "It was a unique opportunity to look at these animals' anatomy in detail.
"And that's what we'd been missing."
Dr Pyenson and his colleagues examined the jaws of fin and minke whales, dissecting them and using high resolution medical imaging to examine the carcasses.
Finding this structure, the researcher said, "answered a lot of outstanding questions".
A rorqual whale's feeding lunge was "one of the largest biomechanical events on Earth", said Dr Pyenson.
"This shows us how they do it so quickly, co-ordinating the inflation of the throat pouch with the opening of the jaws... and closing their mouth to prevent prey escaping - all in under 10 seconds."
Dr Bill Sellers, a zoologist from the University of Manchester, said that this was an "amazing discovery".
"They've found an organ we didn't know was there, which is remarkable considering people have been chopping up whales for hundreds of years."
Dr Gareth Fraser from the University of Sheffield added that the discovery revealed a unique adaptation that mammals had made to an "aquatic lifestyle".
It showed, he said, "how much we still have much to discover, even from the largest ocean residents".
|Sam1||Jun 17 2012, 12:21 AM Post #13|
||People tend to be obsessed with teeth and blood, yet this creature here- by far the biggest, quantitatively most extreme predator ever- leaves them largely indifferent towards anything else apart it's size.|
|Grey||Jun 17 2012, 04:10 AM Post #14|
I agree, but there's something obvious that raptorial, active predators are much more corresponding to the definition of what a hunter is.
Filter-feeders are technically predators but even in scientific goldmine, they're not considered as such.
Sure, if we were krill, we wouldn't argue that...
Reconstitute Extinct Species How They Looked Like, Not How You Want They Looked Like|
Animals, Not Monsters
|Sam1||Jun 17 2012, 07:03 AM Post #15|
Couldn't have said that better, Grey..I think it's the hunter-gatherer DNA that causes this human fascination with "raptorial" predators.
And now, back to the whale
|1 user reading this topic (1 Guest and 0 Anonymous)|
|Go to Next Page|
|« Previous Topic · Cetacean, Pinnipeds & Sirens · Next Topic »|