lunes, 6 de septiembre de 2010

Fourth and Fifth Stage, Shark Project

Before I begin to tell you about the next Shark Project Stage, I would like to share with you that in previous days I had the chance to photograph whale sharks at the northeast of Isla Mujeres, Mexico; where we had the opportunity to take pictures of the biggest fish in the ocean, here are some photos from the expedition. 

In addition, I was at Isla Guadalupe with the purpose of studying up close the shark with which I am going to finish this project, THE GREAT WHITE SHARK, here are some images.

Fourth and Fifth Stage
Shark Project

Next Tuesday, September 7, I will be traveling to Catalina Island, California, USA. Here, I will meet with my good friend Eli Martinez, Editor from Shark Diver Magazine; with the intention to photograph the Blue Shark and the Mako Shark.

Here are some specifications about these species.

 Blue Shark (Prionace glauca)
Blue shark is specie from the elasmobranquio cacarriniform of the family Carcharhinidae. This is a pelagic shark, cosmopolitan, distributed all through every ocean and sea. It has received some common names according to the place: Spain and Mexico, known as “Tintorera” or “Tiburón Tigre”, Uruguay and Argentina “Azul”, USA and United Kingdom as “Azulejo” and in Japan as “Yoshikirizame”.

The Blue Shark is a shark with a slim and stylish body, its snout is conic and long, has big eyes, as every cacarriniform, they are provided with a nictitating membrane which is a semitransparent eyelid that goes upside down and protects the eyeballs when they are fighting with their pray. They own five gill slit, two dorsal fins, two pectoral fins that are long and thin and a caudal fin provided with an upper lobe extremely thin. Have a white coloration in the ventral area and, a dark metallic blue in the rest of its body. The teeth, which fall often, are constantly replaced; their teeth have a triangular shape with serrated edges. The Blue shark is 8.20 feet and weighing 176 pounds, even though there have been a registry case of adult females with measures over 13.12 feet and a weigh of 484 pounds.
As a particularity, is worth mentioning that due to the measure of its nose, their jaws had evolved so they can bite easily, because the upper jaw is projected forward, so they do not need to lift their heads to have a proper bite.

Their diet is of fishes such as mackerel, herring, grouper, gadidae, squid and sea birds. It may be aggressive towards humans. Usually hunt in pairs or small groups. He is used to swim great distances to get his food. He can travel distances up to 3,418 miles.
The blue shark is viviparous. The sexual maturity is in between five and 6 years in females and four or five years in males. Fertilization has placed inside of the female shark; the male fertilizes her thanks to a couple of special pelvic fines called pterigopods. Females have two uteri giving birth in between 4 to 135 offspring; the newborn blue sharks measure approximately 40 cm. As the same as other viviparous sharks; females lose their appetite before birth to avoid devouring their own. Gestation lasts between 9 to 12 months. Blue sharks are very independent at birth and instantly seek shelter from predators, among them, their own parents.

The Blue shark is an animal of nomad oceanic manners; any calculations done about their population is inaccurate. Even though, it is consider, based on estimations about sport fishing, blue shark is under a low risk of extinction. IUCN differs on the idea, and they had included the blue shark in the red list of threatened species.

Reaction to Divers:
Usually they are attracted with bate, situations in which may get to be aggressive. Big blue sharks had been seen attacking humans. The blue sharks out of these situations in which they are lattracted with bate rarely found with divers.

 Mako Shark (Isurus oxyrinchus)

The Mako shark or short fin (Isurus oxyrinchus) is a species of elasmobranquious laminiform, family of the Lamnidae. It has an ample distribution: Pacific Ocean, Atlantic, Indian Ocean, Mediterranean Sea and the Red Sea.
Their meet is often confused with grouper fish and the emperor fish, getting to believe they are the same fish, and buying it for the same price but these three spices are different among themselves.

The Mako shark is a big shark with fusiform, robust, solid and very hydrodynamic. The nose is conic and point, and the mouth is big and narrow. The eyes are round, black and medium size. Medium scapulars fins slightly rounded at the end. The first scapular dorsal has its origin right behind the scapulars; second dorsal and anal are tiny, big caudal fin with wide lobes and in shape of a half moon, the superior lobe slightly bigger than the inferior lobe. Mako sharks have five big gill slits. They have huge teeth, with smooth edges. Their back is of a dark blue, lighter on the sides, and white on the belly.

The Mako shark is of a great size, there is a quote of a captured female of 14.76 feet. The average size of the largest specimens is around 11.48 feet and 19.69 feet, weighing up to 1,540 pounds and 1,650 pounds.
Like the rest of the sharks belonging to the Lamnidae family, keep their body temperature above average, this allow them to have a quicker digestion, tripling their muscular mass. It is a pelagic shark of oceanic manners, although he gets close to the costs searching for food reaching beaches and ports.

Mako shark is a viviparous shark, with an offspring between four and five fetus, the largest offspring registered is of 16 sharks. These little sharks’ measure at birth 2.3 feet and they will grow according to their gender, males to 6.23 feet and females 8.53 feet – 9.19 feet.

This is a powerful and fast hunter; his diet is of fishes (small as herring, mackerel, sardines, skipjack, little tunny etc. or big fishes, as red tuna, swordfish, marlins, and sailfish) squids, other sharks, turtles, dolphins, even there had been cases of attacks to small cetaceans due to their size and aggressiveness. This is the most important predator of the swordfish (Xiphias gladius) which represents an important part of the Mako diet. There is an example of a Mako that weighed over 660 pounds, and in his stomach was an undigested swordfish.

The Mako shark is a very active, with huge force and great velocity. According to recent tests, this shark can reach speeds of more than 77 m/h, which grants him the title of the fastest animal in the ocean, this title belonged to the sailfish with an average velocity of 68.35m/h. The secret of such power and speed is its perfect hydrodynamic, muscular mass, caudal fin in the shape of a half moon and the fact of being homoeothermic, which triples his muscular potential allowing him to have abrupt starts. This combination of power and velocity gives them the ability of jumping out of the water, just like the great white; these jumps are only when he is caught in a fishing hook, where he reaches heights of 19 to 26.25 feet.

When I get back from this expedition, I will share with you the logbook with some photographic material.

Gerardo Del Villar

More about shark proyect:

Stage one:

Stage two:

Stage three:

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