A whale of a mystery: scientists investigate the puzzling death of an endangered sea creature.
The Canadian Coast Guard (CCG) receives a phone call. The caller says a dead whale is drifting off the coast of Yarmouth, Nova Scotia. The CCG immediately sails to the reported site. Members of the agency use ropes to tie the whale carcass to their boat and tow it onto a remote beach in Kelley's Cove, a seaside village in Yarmouth.
At first glance, it is hard to identify the dead 40-ton animal: a North Atlantic right whale. When alive, the marine mammal has a glossy black body. But the carcass lying on the beach looks like a giant white blob.
Agents from the Canadian Department of Fisheries and Oceans rush to the scene. As they study the whale carcass, they wonder how the animal died. They are particularly concerned because the North Atlantic right whale is an endangered species. Approximately 400 members of this species exist in the world today, and they are at risk of dying out. So whenever a right whale dies in Canadian or U.S. waters, that country's wildlife officials immediately call upon experts to perform a necropsy. This medical exam offers clues to how the animal died, and the information could help officials find ways to better protect the endangered whales.
September 4, 2006 KELLEY'S COVE
Michael Moore, a veterinarian and biologist at the Woods Hole Oceanographic Institution (WHOI) in Massachusetts, arrives with his team of researchers. He eyeballs the whale remains and immediately picks up clues that the whale has been dead for a while.
When a living thing dies, it decomposes. Bacteria inside the organism eat away at the body, causing the carcass to decay over time. "During decomposition, the whale's external features gradually fall off," says Moore. Nearly all of this whale's glossy black epidermis, or outer skin, has peeled off. Also, "a freshly-dead right whale is about 10 feet in diameter," says Moore. This dead whale looks greatly deflated.
A decaying whale is like a flattening tube of toothpaste, explains Moore. Just underneath the whale's skin is a thick layer of blubber. This spongy and oily material is very resistant to decomposition. But inside the whale is another story. During decomposition, the whale's muscles and viscera, or soft internal organs including the lungs and intestines, all slowly liquefy into a substance that is similar in consistency to toothpaste. But this soup of decayed flesh is a lot smellier than toothpaste, says Moore. This gunk gradually leaks out of the dead whale's mouth. By gauging the size of the deflated whale's body, Moore gets a sense of how much of the whale has decomposed inside.
A whale necropsy is messy; whale blood and oil could splatter onto the examiner. So Moore's team puts on protective gear such as foul-weather pants. The researchers start the examination by studying the whale's external features and taking its measurements. They learn that the whale is a female and that it is 1,465 centimeters (48 feet, 1 inch) long. They also look at the whale's body for signs of trauma or diseases. Besides dent marks from the ropes used to tow the animal onshore and a couple of shark bites. Moore finds no clues that point to the whale's death. The only way to dig deeper into this case is to look inside the whale.
Using sharp knives, Moore and his team cut into the whale blubber. Bingo! Blubber is normally light pink in color. But a large section of blubber on one side of this whale is red. "That's a sign of bruising," says Moore.
A bruise usually forms when a blunt object hits a body. Moore explains: When a baseball hits you, you don't get cut because the blunt ball doesn't pierce your skin. But the impact of the hit causes the various blood vessels that feed into the tissues beneath your skin to burst. As red blood cells spread into the tissues, a bruise forms. Similarly, a collision with a blunt object is likely to have caused the whale blubber to bruise.
September 5, 2006
A new day begins and Moore and his team are eager to learn what hit the whale and how it died. So they proceed to peel the blubber off the whale to see what additional clues hide beneath.
Moore finds that 75 percent of the whale's muscles remain, but that all of its viscera had already liquefied and leaked out of its body. "The animal had decomposed so much that its rib cage had somewhat collapsed," says Moore. Through previous studies, Moore knows that this state of decomposition is usually seen in whales that have been dead for approximately two weeks.
The team continues dissecting the whale and soon discovers a large number of broken bones. The researchers remove the whale's bones and set them on the beach. Then, piece by piece, the scientists use the bones to reconstruct the whale's skeleton. The completed structure gives Moore and his team a better idea of which parts of the whale skeleton are intact and which parts are broken. The finding: Many vertebrae, or individual bones that make up the spine, were fractured near the whale's chest and lumbar (lower back) regions.
Although the whale's tissues are still being analyzed, Moore feels confident that he has gathered enough clues to draw a conclusion: A large, blunt object hit the whale hard on one side--the side that was bruised. That impact broke the animal's backbones. As a result, the nerves that send signals from the whale's brain down its spine were severed. Without brain signals to direct its tail and other body parts to move, the whale was probably paralyzed and couldn't swim. "It was also in a lot of pain and bled a lot," says Moore. "The whale probably died within a few hours of being hit."
Over the years, Moore has learned that most North Atlantic right whales die from getting hit by cargo ships or from becoming tangled in fishing nets. The whale in this case most likely died from a ship strike.
To protect these endangered whales, the U.S. and Canadian governments have long-standing laws that prohibit ships from coming within 500 yards of right whales. Still, many right whales die from shipping and fishing activities every year. Moore and other scientists hope that their findings about each right whale's cause of death will help the U.S. and Canadian governments find better ways to help save the species from extinction.
Why is this whale's coloring so odd-looking?
What information could be hiding inside the whale?
Which of these parts of the whale is strange in color
How did all of these whale bones break apart?
nuts & bolts
The North Atlantic right whale used to widely roam the Atlantic Ocean. When commercial whaling began approximately 1,000 years ago, the species' populations began to plummet. To protect the species, whaling of the North Atlantic right whale has been banned since 1935. Despite the decades of protection, "We haven't seen a substantial increase in the number of whales," says Michael Moore of WHOI.
Today, roughly 400 Eubalaena glacialis remain, living along the coast of North America. Scientists believe this population is not growing much because too few whales are being born and too many are dying from ship strikes or from getting caught in fishing nets. And the whales' migration route puts them right in the line of danger (see map, left).
In the warmer seasons, the whales feed on zooplankton (small, drifting animals) in northern waters. In the cooler seasons, the whales swim to southern waters to calve. This north-south migration route intersects with busy shipping traffic that transports trade goods between the U.S. and other countries. The whales' coastal route also coincides with prime commercial fishing areas.
THINK ABOUT IT: How might governments, scientists, and industries work together to save the endangered right whales?
Jump-start your lesson with these pre-reading questions:
* Adult North Atlantic right whales (Eubalaena glacialis) are between 14 and 17 meters (45 and 55 feet) in length and weigh roughly 6:3,500 kilograms (139,700 pounds). How might a dead right whale change in its body size and appearance over time?
* The North Atlantic right whale is named as such because early whalers identified them as the "right" whale to hunt. These whales were prized for their thick, oily blubber. But whaling caused the whale populations to plummet. Approximately how many North Atlantic right whales remain in the world today?
* One individual right whale, first identified in 1935, was spotted again in 1959, 1980, 1985, and 1992. The last sighting of this whale was in 1995. What unique physical features might a right whale have that would allow scientists to tell one right whale apart from another?
* In the article you learned that the commercial shipping and fishing industries kill many North Atlantic right whales each year. How might your consumer lifestyle be linked to driving these whales to extinction? How might governments, industries, consumers, and scientists work together to ensure that humans get the goods they need and that right whales are protected at the same time?
HISTORY: Have students research the history of whaling in North America. Then have each student imagine his or her life as a whaler living in the 1600s or 1700s. Have each student write a journal entry--from the whaler's point of view--about life onboard an early whaling vessel. For research help, visit the New Bedford Whaling Museum's Web site: www.whalingmuseum.org/kendall/amwhale/am_index.html
* For more scientific and conservation information about the North Atlantic right whale, visit the North Atlantic Right Whale Consortium at: www.rightwhaleweb.org
* WHOI's Currents magazine has a special issue devoted to the North Atlantic right whale. You can read the issue online at: www.whoi.edu/institutes/oli/currenttopics/ct_rightwhales.htm
* To learn about the U.S. government's efforts to protect marine mammals, visit: www.nmfs.noaa.gov/pr
A Whale of a Mystery
DIRECTIONS: Match the word in the left column with the correct phrase in the right column.
--1. necropsy a. lower back --2. epidermis b. soft internal organs --3. blubber c. medical exam for learning how an animal died --4. callosity d. small, drifting animals --5. viscera e. individual bones that make up the spine --6. vertebrae f. outer skin --7. lumbar g. thickened bumP of skin on a right whale's head --8. zooplankton h. spongy and oily material found in whales
1. c 2. f 3. h 4. g 5. b 6. e 7. a 8. d
In "A Whale of a Mystery" (p. 18), you learned that approximately 400 North Atlantic right whales remain in the world. So scientists take notice whenever they spot a right whale in the waters.
Below is a chart showing some of the sightings for a female right whale named Pediddle. Use the information in the chart to mark on the map below where and when she was sighted. Then use a colored pencil to connect the marks and draw a possible migration route for Pediddle during the year 2001. Use another colored pencil to draw a possible migration path for Pediddle between May 5, 2004, and May 4, 2005.
Sightings for Pediddle Year Date Sighting Area 2001 January 16 Georgia coast 2001 February 10 Florida coast 2001 June 1 Great South Channel 2003 May 15 Great South Channel 2003 June 29 Massachusetts Bay 2004 May 5 Great South Channel 2004 December 31 South Carolina Coast 2004 January 25 Florida coast 2005 February 12 Georgia coast 2005 May 4 Great South Channel For more about Pediddle, visit http://rwcatalog.neaq.org. Pediddle's ID number is 1012.
Use the information above to answer the following questions in complete sentences.
1. Where was Pediddle usually sighted during the month of May?
2. Compare the two migration routes that you drew for Pediddle. By studying the two paths, what can you infer about Pediddle's migration pattern?
1. Pediddle was usually sighted in the Great South Channel during May.
2. Pediddle usually spends the winter months (January and February) in southern waters, such as off the coast of Georgia and Florida. She usually spends the spring and summer months (May and June) in northern waters, such as the Great South Channel.