The Winnowing is a science fiction short story by Isaac Asimov. The story was written at the request of William Levinson, editor of the US publication Physician's World , but when the latter ceased publication, the story was returned to the author, who then sold it to Analog. It appeared in the February edition. In the year , the world's population of six billion is suffering from acute famine.
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Gary Lynn Fjellgaard is a Canadian country music singer-songwriter. The angelsharks are a group of sharks in the genus Squatina of the family Squatinidae. They inhabit sandy seabeds close to m in depth. Many species are now classified as critically endangered by the International Union for Conservation of Nature. Once common over large areas of the Northeast Atlantic from Norway , Sweden and the Canary Islands , to the Mediterranean and Black Seas, there is now significant fishing pressure which has resulted in significant population declines.
Squatinidae are unusual in having flattened bodies and broad pectoral fins that give them a strong resemblance to rays; this genus is the only one in its order Squatiniformes.
They occur worldwide in tropical seas. Most species inhabit shallow temperate or tropical seas, but a few species inhabits deeper water, down to 1, m. Angel sharks are sometimes called monkfish , although this name is applied to members of the genus Lophius. While some species occur over a wide geographic range, the majority are restricted to a smaller area.
Restriction in geographic range might be as a result of the behavior of Squatina species, which are ambush predators with a corresponding stationary bottom-dwelling habit. Thus, trans-ocean migration is unlikely though large-scale coastal migratory patterns have been reported in species such as Squatina squatina.
While the anterior part of the angel shark's body is broad and flattened, the posterior part retains a muscular appearance more typical of other sharks; the eyes and spiracles are dorsal and the five gill slits are on its back. Both the pectoral and pelvic fins are held horizontally.
There are two dorsal fins, no anal fin and unusually for sharks, the lower lobe of the caudal fin is longer than the upper lobe. Most types grow with the Japanese angel shark, known to reach 2 m; some angel sharks have deformities.
These can include skeletal deformities, as lateral spinal curvature, humpback curvature, axial spinal curvature, missing fins, additional fins, deformed snout, more; these abnormalities have only been found in a few sharks, but the causes of these deformities have been found to be from dietary nutritional imbalance, genetic factors, traumatic injuries, or stress in the specimen.
In , two sharks were captured and examined, both showed a lateral spinal curvature and a humpback curvature. Both the animals had the curvature in the middle of their pectoral fins, but the deformity did not affect their swimming capacity. Spinal scoliosis has been reported to be diverse in sharks, but in pelagic sharks that depend on their swimming abilities to catch their prey. For the Angel shark S. Right now, research is assuming most physical injuries are caused by human interactions because of the constant interference in costal areas, where most of the sharks reside.
There have been few attacks reported, what few have occurred were due to accidental stepping on of buried newborn sharks. Landings of Pacific Angel Shark increased through the mids and reached over tonnes in , becoming the shark species with the highest total reported landings off the US West coast that year. Angel sharks possess extensible jaws that can snap upwards to capture prey and have long, needle-like teeth. They bury themselves in loose sediment lying in wait for prey, which includes fish and various types of mollusks , they are producing litters of up to 13 pups.
Pacific Angel Shark pups are born from March to June in deep water — to feet — to protect the pups from predators. Angel Sharks reside in depths of 1—m and can be seen on muddy or soft benthic substrata where they can blend in as they lie in wait.
Areas with the greatest habitat suitability consist of ideal temperature, oxygen and depth levels. Members of the family Squatinidae have a unique camouflage method, which goes hand in hand with how they obtain their food, involving lying still on the sea floor, making rapid lunges at passing prey, using negative pressure to capture prey by sucking it into their mouths.
Morphological identification in the field can be difficult due to discontinuity and similarity of species. In this specific circumstance, the sharks' place within the class Squatina comprises three species in the southern part of the western Atlantic. The three species observed were Squatina Guggenheim , S.
These three species are listed in the IUCN Red List as threatened, they are now protected under Brazilian law, which makes angling and exchange illegal. DNA barcoding revealed trafficking of these protected species. Angel sharks inhabit tropical marine environments, they are found in shallow waters at depths from 10 to feet off coasts. They are known to bury themselves in sandy or muddy environments during the day, where they remain camouflaged for weeks until a desirable prey crosses paths with them.
At night, they take a more active cruise on the bottom of the floor. Squatina preys on fish and cephalopods. Although this shark is a bottom-dweller and appears harmless, it can inflict painful lacerations if provoked, due to its powerful jaws and sharp teeth, it may bite if a diver grabs the tail.
Angelsharks have a unique way of breathing compared to most other benthic fish. They do not. WikiVisually Top Lists. Trending Stories.
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The story was written at the request of William Levinson, editor of the US publication Physician's World , but when the latter ceased publication, the story was returned to the author, who then sold it to Analog. It appeared in the February edition. In the year , the world's population of six billion is suffering from acute famine. The World Food Organization decides on desperate measures to decrease the population by a process of triage. They propose to do this by adding selective poisons to certain food shipments to grossly over-populated areas. They attempt to blackmail biochemist Dr.