Wednesday, November 17, 2010

How To Keep Leather Shoes From Creasing

The ocean at 332 degrees.

or Sharks The Sharks are a large group of Vertebrate Chondrichthyes Subclass Elasmobranchii Selachimorpha called, in more familiar terms this means that it is a great group that forms a Elasmobranchii Superorder of fish skin and cartilaginous skeleton denticular .
still had to pass 200,000,000 years for the first dinosaurs should give their first steps of evolution on land where the simple but revolutionary design of the Sharks began to cross the shallow seas around the globe. A balloon that human eyes would be practically unrecognizable, as if it were another planet, because the fragmentation of the supercontinent Pannotia due to tectonic movements had created a landscape dominated by a global ocean topped by a great southern continent called Gondwana accompanied by two smaller masses, called Siberia Euramerica, located in northern latitudes and Ecuador respectively, the three great continents were relatively close to each other and include large areas of sheltered shallow seas dotted with thousands of islands. It was a world that might well seem strange, life had just taken his first steps on land and seas hold primitive but very different creatures from which the Sharks did not stand at all, although its qualities for survival and quirky original designs, characterized by rare forms with all sorts of appendages, oral toothed wheels, body extension and a host of non-anatomical ons soon open the way to colonize numerous ecological niches around the globe to the point of monopolizing the fishing life for about 300,000,000 years, when over 70% of marine fish were sharks. The keys to its success? Unusual sensory perception, skin denticular that optimized and continues to optimize its qualities swim and avoid hydrodynamic turbulence and an enviable adaptability. However, the mass extinction occurred at the end of the Permian period, 250,000,000 years ago, hit hard this group of cartilaginous fish resistant to deepen their greatest weakness: Its low fertility rate motivated by a life characterized by aggressive antisocial sexual individuals of the same species. Not surprisingly, 96% of marine species were doomed to rapid extinction of not more than 100,000 years.
recovered from that catastrophe, the Sharks have returned to fill the role as predators, apart from that during certain periods, sauropsids marine as mosasaurs and plesiosaurs or Mammals Orcas as they temporarily stolen the spotlight and sometimes even the highest ranks of the food chain. Its adaptability has led them to take from forms as distinctive and recognizable as the blue shark (Prionace glauca ) or the great white shark (Carcharodon carcharias ) to unusual and peculiar aspects such as the hammerhead shark (Sphyrna mokarran ) or rays, skates and sea eagles taking their own evolutionary path. It is without doubt the design of those sharks, commonly called "cuckold" or "Hammer" one of the most specialized of those can be seen in our days and from then many of its peculiarities are still a mystery to science, mystery began to unravel, however. Sharks hammer
Cuckold Family Sphyrnidae are marine and are included in the Order of Carcharhiniformes. Broadly, their anatomy is akin to other components of this Order: dynamic, muscular body, skin denticular, ovoviviparous reproduction and advanced sensory instruments, but a notable feature distinguishes at first sight of his fellows, it is obviously his head, long cross in relation to the body as if it were a hammer. A trait that does not go unnoticed.

Hammerhead Shark Sphyrna or mokarran . Recreation
Rialp "Junior."


Biomolecular Research, based on analysis of mitochondrial DNA markers have defined the origin of this striking form, confirming that the closest relatives of these sharks are the members of the genus Carcharhinus , which has species almost unknown to the public such as the Galapagos shark, the shark or the most popular gray reef shark, placing their common relative, the Carcharhinidae primitives, such as common ancestors of each other. However the line separation evolutionary hammerheads with respect to their closest relatives is at the end of the day or early Oligocene, Eocene, so this group has had more than 30,000,000 of years to adapt their morphological design for greater specialization as evidenced by the low turn fossil record, limited to several teeth and some vertebrae and impressions and skeletal body.
Today this small family is composed of two genera and nine species Eusphyra Gender the controversy has only Eusphyra blochii Horned or planner, very primitive and often difficult to classify, while the Gender Sphyrna includes the other species, which are Sphyrna corona crowned or hammerhead shark, Sphyrna cowardliness whales and hammerhead sharks, Sphyrna lewini or common Hammerhead Shark, Sphyrna half spoon or hammerhead shark, Sphyrna mokarran or hammerhead shark, Sphyrna or Horned sharks sharks, Sphyrna tudes or hammerhead shark Sphyrna zygaena ojichico and hammerhead shark or cross. All rooms have their own sensory array of sharks such as lateral line that allows them to detect movements and vibrations in the surrounding water, but this particular family presents in the shape of their heads, a special bracket to accommodate more specialized bodies of sharks in order to sharpen up the limit. A notable example is the dispersion of blisters Lorenzini, which are present in most sharks, but among the Sphyrnidae get their best, because its higher density and available under one head of this magnitude not only allow Animal detect weak electromagnetic fields emanating from prey in the water, but provides them with sufficient sensitivity to detect even under several inches of mud and sand on the seabed, making it the successful hunters sedimentary dam are: special family that is out of reach of other sharks. However, also the smell of the Cuckold is particularly efficient because sense since this instrument is located in two ends of the head, provides a directional perception that not only detects a speck of blood or other fluids per million of water, it is also able to determine their origin with high accuracy. On the other hand also the eyes are separated on both sides of the head, a recent study conducted by Jim Dawson for the National Geographic Society has determined that your vision diplopia searches a field of view of 182 º angle on each side obtaining a small frontal area of \u200b\u200bonly 32 º stereo. The weakness of this approach is that the shark much a blind spot right in front of himself and can not see head-on at a distance less than twice the width of your head, so that short distances come into play the other senses for the detection and capture of fish, molluscs and crustaceans that make up its diet. Needless to state that also lack the posterior visual perception at an angle of 28 º. Notably, the tapetum lucidum behind the retina located exponentially increases the sensitivity to light, allowing night hunting or great depth.
In short, this is a highly familiar group specialized evolutionary adaptation which has sacrificed some discretion and hydrodynamics for greater specialization has allowed them to find food without having to compete for prey with most other sharks, however, this is not the end of his superb adaptation by example, we can see evolution in action after discovering that the size of the head of Sphyrna mokarran , a species with more than six feet long and half a ton of weight, which used to be nourished on the open sea instead of using the seabed in the style of Sharks "classic" is reduced generation after generation, because its unique design is less effective in these areas.
The Sharks have inhabited the seas and oceans around the world for over 400,000,000 years, occupying much of that time the highest ranking of the marine food chain, but today its disappearance rate is comparable to that seen during the great Permian extinction, but this time at the hands of a species, humans, that kills irresponsibly either for commercial, sport, through carelessness or by an irrational hatred of magnificent predators, if we take care and stop chase, ending its long evolutionary journey may be approaching, the whole tragedy and of course an environmental debacle that we must avoid at all coast towards the future and our own.
is my humble wish to dedicate this article to Javier Juarez Sanchez de Girona, Spain, a lover Sharks confidence placed in me despite being a complete unknown. Get my full support and respect mood face of adversity. Mr. Javier health.

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