Basking Sharks:

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The Basking Shark: Hope for the Future? Introduction - What are the biological characteristics, habitat, and value of basking sharks? I. Interrelated life forms populate the oceans. A. Photoplankton synthesize food. 1. Using carbon dioxide 2. Dissolving minerals 3. Collecting sunlight energy B. Small fish consume photoplankton. C. Zooplankton eats minute plants. 1. Sea worms 2. Jellyfish 3. Crustaceans D. Food chain ends with large creatures. 1. Whales 2. Sharks E. Some of the largest creatures feed on the smallest. II. Ocean creatures feed at various depths of the sea. A. Most large creatures gather at the top layer of the ocean. 1. Food is plentiful. 2. Water is warm. B. Small creatures feed on organic debris deep in the ocean. 1. Fish 2. Crustaceans III. Fish species include 340 members. A. Skates B. Rays C. Chimeras D. Sharks 1. Not a bony fish 2. Skeleton made of cartilage IV. Location of sharks A. Marine waters B. Tropical seas C. Subtropical waters V. Length of the shark varies. A. Whale shark as great as 49 feet B. Cookie-cutter shark as small as 19 inches VI. Agressiveness varies. A. Most appear to be aggressive carnivores. B. Some of the largest are plankton-eaters. VII. Sharks have not changed from the Cretaceous Period. A. Caused by great diversity in behavior B. Variety of sizes C. Excellent adaptation skills VIII. Sharks belong to class Chondrichthyes. A. Scientific names of sharks 1. Whale sharks - rhincodon typus 2. Cookie-cutter sharks - Squaliolus laticaudus 3. Bull tiger shark - Galeocerdo cuvier 4. Spiny dogfish - Squalus ancanthias 5. Great White Shark - Carcharodon carcharias 6. Hammerhead shark - Sphymidae 7. Blue Shark - Prionace glauca 8. Basking Shark - Cetorhinus maximus B. Skeletons of Chondrichthyans are made of cartilage. 1. Can be strenghened by deposits of minerals in areas of stress a. jaws b. vertebrae 2. Lighter than bone since sharks have no swim bladder 3. Material that is flexible for swimming and turning 4. Grows throughout life of shark IX. Specific characteristics of the basking shark. A. Found in temperate oceans B. Length up to 43 feet C. Swims near surface 1. Seen sunning near top of water 2. May be in variety of positions a. back b. side c. high in water D. Feeds on plankton E. Enormous fish F. Mouth is large 1. Wide 2. Small-toothed G. Gill slits 1. Lined with long, bristle-like rakers 2. Five sets 3. Trap food of plankton H. Originally hunted for its liver oil I. Not known to be dangerous J. Color blends with environment 1. Upper, dorsal surface is greyish brown 2. Lower, ventricle surface is white 3. Seen less by enemies K. Fusiform body 1. Rounded and tapered at both ends 2. Reduces water friction 3. Requires minimum energy to swim L. Placoid Scales 1. Regular pattern 2. Reduce friction 3. Different from centoid scales of bony fish M. Characteristics of the head 1. Fins formed in half-moon pattern 2. Mouth on underside of head 3. Wide separation of nostrils N. Characteristics of the teeth 1. Small 2. Great in number 3. Formed in parallel rows 4. Not meant for carniverous purposes 5. Rows of teeth develop continuously as replacements for functional teeth 6. Not used for attack purposes X. Scientists have recorded measurements of the basking shark. A. Babies are five to six feet at birth. B. Pacific Ocean basking sharks 1. 23 feet long 2. 6,600 lbs. C. Atlantic Ocean basking sharks 1. 30 feet long 2. 8,600 lbs. D. Others have observed lengths from 35 - 50 feet. XI. Sharks have been observed in many places. A. Gulf of Maine swimming alone B. Northeastern United States in large numbers C. In winter, they move to warm climate D. Known boundaries 1. North - Nova Scotia and Newfoundland 2. South - Mediterranean Sea 3. West - North Carolina XII. Breeding patterns are largely unknown. A. Produce live young B. Ovaries contain six million immature eggs. XIII. Sharks have been studied as a cure for cancer. A. Ability to resist disease B. Few tumors have been discovered by Smithsonian Institution C. Do not form tumors when exposed to cancer-causing material D. Studies may lead to help for cancer patients. 1. Immunoglobin (IgM) in shark's blood attacks invading substances. 2. Shark cartilage may resist penetration by capillaries, shrinking tumors. 3. Drugs of cartilage may control spread of blood vessels that feed tumors. E. Several science labs have studied the use of shark cartilage for cancer cures. 1. Dr. I. William Lane - Sharks Still Don't Get Cancer a. Studied in clinical trials at U.S. Food and Drug Administration b. Stops formation of new blood vessels c. Prevents cancerous tumors through process of antiangiogenesis 2. Jing Chen in 1989 a. Oil emulsion from the Cetorhinus maximus is brand new medicine. b. Improvement of patient's condition (1) Weight increase (2) Tumor shrinkage (3) Life extension 3. Cancer Treatment Research Foundation study is disappointing. a. Cartilade brand shark cartilage was ineffective against advanced cancer cases. (1) Breast (2) Colon (3) Lung (4) Prostate b. None of the 47 patients showed even partial tumor reduction. 4. Current studies indicate inconclusive results. Conclusion: Current investigations and modern knowledge of the basking shark have opened new areas of study with implications for the health of man. The Basking Shark: Hope for Cancer Cure? The Basking Shark: Hope for a Cancer Cure? The oceans of the world are populated with distinct but interrelated forms of life. The nourishment for all ocean life originates in the sunlit surface layers, where microscopic plants called phytoplankton use carbon dioxide, dissolved minerals, and the energy of sunlight to synthesize food. Small fish and zooplankton - drifting creatures such as sea worms, jellyfish and crustaceans - browse on these minute plants, and the food value thus provided moves through successive steps of predation, up the marine food web to the largest sea dwellers (Whipple 132). Most of the whales, fish, and squids gather at the top layers of the ocean where the food is plentiful and waters are warm. The fish and crustaceans of the depths are fed by organic debris - excrement and corpses - that drifts down from the surface waters. The ocean food chain begins with the small plankton and ends with the largest of the whales and sharks. Interestingly enough, some of these largest species feed on the smallest of ocean creatures (Whipple 132). The shark is a member of the three hundred forty species of fish that along with skates, rays, and chimeras are sharply distinguished from the vast number of bony fish species by their skeletons made of cartilage. Sharks are chiefly marine fish found in all seas and are especially abundant in tropical and subtropical waters. They vary in size from the largest, the whale shark, which is forty-nine feet in length to the cookie-cutter shark which is less than nineteen inches long. Sharks are best known as agressive carnivores that even attack their own species. They eat nearly all large marine animals in both shallow and deep seas. Two of the largest of the species, however, eat only plankton (98 Encyclopedia). The sharks that exist today have not changed much from those in the Cretaceous Period which occured more than one hundred million years ago. This ability to live without much change over many centuries is caused by their great diversity in behavior and in size, showing excellent adaptation skills (98 Encyclopedia). Sharks belong to the class Chondrichthyes along with the rays, skates, and other cartilaginous fish. The whale shark is classified as Rhincodon typus, the cookie-cutter shark as Squaliolus laticaudus, and the bull tiger shark as Galeocerdo cuvier, the spiny dogfish as Squalus ancanthias, and the great white shark as Carcharodon carcharias. Hammerhead sharks make up the family Sphymidae. The blue shark is named Prionace glauca. The basking shark is classified as Cetorhinus maximus. It is this last shark species on which this paper concentrates (98 Encyclopedia). Chondrichthyans differ from osteichthyans, or bony fishes, whose skeletons are heavily calcified. A shark's skeleton is made mostly of cartilage that can be strengthened by deposits of minerals in areas subjected to special stress such as the jaws and vertebrae. Cartilage is an ideal tissue for sharks for several reasons. First, cartilage is lighter than bone, important for sharks which have no swim bladder...Second, cartilage is a relatively flexible material, giving tensile force to swimming and turning movements...Lastly, cartilage can grow throughout the life of a shark (Sharks and Stats 1). The basking shark is the common name for the enormous fish belonging to the shark family. It is found in all temperate oceans and can reach a length of forty-three feet. The basking shark usually swims near the surface of the water and feeds on plankton that is strained through its wide, small-toothed mouth and five pairs of enormous gill slits. Each gill is lined with long, bristlelike rakers that trap the plankton. The basking shark was once hunted for the large quantities of oil contained in its liver, but this practice has been stopped. This shark is not known to be dangerous, but its size demands respect (98 Encyclopedia). The basking shark is a huge, greyish fish that is only second in size to the whale shark. Like most sharks, it is characterized by a fusiform body which is rounded and tapered at both ends. This streamlined, cylindrical shape reduces the friction of the water and requires a minimum of energy to swim. In addition, the placoid scales which are arranged in a regular pattern reduce the friction of the water by channeling the water flow over the body. These are very different from the ctenoid scales of bony fish which overlap to provide both protection and suppleness (Sharks and Stats 2). The color of the upper surface of the basking shark is a greyish brown, slate grey, or even black. The lower surface is usually white (Bigelow and Shroeder). This countershading, a type of coloration in which the dorsal side is darker than the ventral side, enables the shark to blend with the environment and be seen less easily by predators and prey (Sharks and Stats 1). Observations from scientists have recorded a variety of measurements from thirty-five to fifty feet in length. The babies are usually five to six feet when they are born. Estimated weights for smaller twenty-three foot basking sharks from the Pacific Ocean are 6,600 pounds where the larger thirty foot basking sharks from the Atlantic weigh as much as 8,600 pounds (Bigelow and Schroeder 147). The fins of the basking shark are shaped in a half moon pattern, the mouth is positioned on the underside of the head, and there is a wide separation of nostrils from the mouth. The gills are so large that they surround the neck of the basking shark with the first pair almost meeting below the throat. On the inner margin of each gill are found a great number of thorny, bristle-like rakers directed inward and forward. The mouth is very large and can open at the corners with ease. On large specimens, the nose is short and cone-shaped with a rounded tip (Bigalow and Schroeder 147). The teeth of the basking shark are formed in parallel rows like those of other shark species. These teeth are very small and great in number to match their function. These sharks have no need to grow large, serrated teeth of the more carnivorous varieties. "Several rows of replacement teeth develop continuously throughout life behind the outer row of functional teeth" (Sharks and Stats 2). The basking shark is a large non-threatening fish that is often seen sunning itself on the surface of the water and that is why it is named "basking." Because of its minute teeth, it is helpless to attack. Often the shark suns itself with its back and dorsal fin high out of the water, on its side, or even on its back (Bigelow and Schroeder). Sometimes it loafs along with the snout out of the water, its mouth open, while gathering its meal of plankton. The shark spends so little time paying attention to boats that it can easily come within harpoon range of shark hunters. These sharks also have been seen jumping out of the water (Bigelow and Schroeder 62). Basking sharks are usually seen in the Gulf of Maine traveling alone. Sometimes, however, they are seen in the northeastern United States and in the northern part of their range in the Atlantic in loose schools that include as many as sixty to a hundred members. During the warm part of the year, basking sharks are frequently seen in the northeastern United States. In the winter, they often move to deeper water where the temperature of the water does not fall so low (Bigelow and Shroeder). The most interesting peculiarity of the basking shark is its curious diet. This large creature eats wholly on tiny pelagic animals. It sifts these out of the water with its greatly developed gill rakers, exactly like other plankton-feeders. Their stomachs have been found packed with minute Crustacea; digestion is so rapid that the food swallowed is soon reduced to a soupy mass (Bigelow and Schroeder). Basking sharks produce live young like other sharks in their species although very little is known about the structure of the breeding patterns. The female is known to have ovaries containing six million immature eggs instead of the few that are prevalent in other sharks (Bigelow and Schroeder). The basking shark was originally thought to be an Artic species. Now, however, it is known that it is an inhabitant of the North Atlantic and the thermal belts of the Atlantic and the Pacific Oceans. The Northern boundary of the normal range of the basking shark of the North Atlantic appears to be Nova Scotia and Newfoundland; the Southern boundary is as far as the Mediterranean Sea. North Carolina appears to form the western boundary (Bigelow and Schroeder). At one time, basking sharks as well as sperm whales were commonly caught off the coast of Massachusetts. Their precious oil was treasured as a source for lamp oil by the colonists. However, their numbers were soon depleted by overfishing (Bigelow and Schroeder). During the last twenty years, sharks and their relatives have been the object of serious study particularly in the search for a cure for cancer: Sharks and their relatives, the skates and rays, have enjoyed tremendous success during their nearly 400 million years of existence on earth. One reason for this certainly is their uncanny ability to resist disease...tumor incidence in these animals is carefully monitored by the Smithsonian Institution in Washington, D.C. (Luer 1). In studies at the Mote Marine Laboratory in Sarasota, Florida, scientists are experimenting to determine whether tumors can be produced in sharks and skates by exposing them to potent cancer-causing chemicals. No changes in the tissues of the sharks or their genetic material ever resulted in cancerous tumors to be formed. After ten years of research, the scientists have concluded that the resistence to disease can be explained by the immunoglobin (IgM) which "circulates in the shark blood at very high levels and appears to be ready to attack invading substances at all times...This information may someday lead to improved methods of immune cell regulation in humans, especially cancer patients" (Luer 1-2). In the 1980's, studies conducted at the Massachusetts Institute of Technology (MIT) and at Mote Marine Laboratory tried to verify the value of using shark cartilage for both cancer and arthritis: These studies of cow and shark cartilage were designed to understand how cartilage is naturally able to resist penetration by blood capillaries. If the basis for this inhibition could be identified, it was reasoned, then it might lead to the development of a new drug therapy. Such a drug could control the spread of blood vessels feeding a cancerous tumor, or the inflammation associated with arthritis (Luer 2). The primary proponent of the benefits of shark cartilage has been Dr. I. William Lane. In his book, Sharks Still Don't Get Cancer, Lane claims that "use of whole shark cartilage has proven so effective as an alternative cancer therapy that it is now being studied in human clinical trials conducted under the auspices of the United States Food and Drug Administration" (6). The benefit of shark cartilage is touted as a therapy which stops the formation of new blood vessels and, therefore, prevents the growth of cancerous tumors. This process was named antiangiogenesis (anti = against, angio = blood, genesis = formation of) (8). Research continues with the basking shark as a subject. In 1989, it was reported by Jing Chen that an oil emulsion from the "Cetorhinus maximus is a brand-new anti-carcinoma medicine made from marine organisms. Marked improvement of the patient's condition such as weight increase, partial shrinkage of the swollen lump and life extension constitute the distinctive features of oil emulsion of Cetorhinus maximus" (41-45). Results of the largest current study announced in May, 1997, by the non-profit Cancer Treatment Research Foundation in Arlington Heights, Illinois, were disappointing. The research found that Cartilade brand shark cartilage was ineffective against advanced cases of breast, colon, lung, and prostate cancer. None of the forty-seven patients showed even partial tumor reduction after twelve weeks (Environmental Nutrition 7). Although Lane's work continues to be followed, research attempts to verify his work has not been satisfactory. It was during a feature story on 60 Minutes when Mike Wallace interviewed Lane in Cuba that the story became well-known in America. The results of the report were inconclusive but the interest of the American people had been whetted (Braun 5). The value of the shark has yet to be fully determined as a medical treatment for human disease. However, the current investigations certainly have opened new areas of study for these massive creatures of the warm oceans who have existed for mil

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