Sharks on new stamps
Five stamps with dangerous sharks were issued on Ascension Island in March 2008. Four of these values were produced in individual sheets of 10 stamps with plain border. These sets are also available in staggered se-tenant strips of four in a single stamp sheetlet with decorative border. The fifth is available in a striking souvenir sheet.
35p Bluntnose Sixgill
The Bluntnose Sixgill (most common sharks have 5 gills) is a primitive shark with relatives dating back 200 million years. It is an interesting species due to its both primitive and current physical characteristics.
As an adult the Bluntnose Sixgill can grow to a massive size. Females tend to be slightly larger than males at around 4.5 meters, although they can attain a length of up to 5.5 meters. Despite its great size it is not considered to be dangerous. This species typically inhabits depths greater than 90 meters, and has been recorded as deep as 1,875 meters.
Although sluggish in nature, the Bluntnose Sixgill is capable of attaining high speeds for chasing and catching its prey. Distributed worldwide it is capable of eating a wide variety of prey.
The mother carries the young within her body until the eggs hatch. Litters generally comprise more than 100 live born pups, each around 70cm long. Such a large number suggests a high mortality rate among the pups.
40p Scalloped Hammerhead
Scalloped Hammerhead sharks are the most common of all the Hammerheads. Mature females can reach a length of more than 4 meters. It tends to inhabit warm coastal waters down to a depth of 300 meters. Whilst Scalloped Hammerheads often swim the oceans alone they can also be seen during the day in very large schools, sometimes counting hundreds of individuals.
This hammerhead species feeds mostly on fish such as sardines, herring and mackerels. Large scalloped hammerhead sharks also eat small-sized shark species. It is considered dangerous, especially in large schools. However it is not aggressive towards humans and most incidents involving humans are probably the result of a startled shark acting defensively.
Scalloped Hammerheads bear their young alive, the females giving birth to between 15 and 30 pups of around 50cm in length. The "hammer" is made of cartilage and is very soft when the young are born so as to facilitate the birth process.
50p Shortfin Mako
The Shortfin Mako is a large shark with a full-grown length of up to 4 meters. It is found in temperate and tropical seas worldwide and at depths of 150 meters. It is highly migratory and they are often found in the same waters as swordfish, a source of food that shares its environmental preferences. Mainly feeding upon bony fish it may also eat other sharks, porpoises and sea turtles.
Shortfin Makos are renowned for their speed and the ability to leap tremendous distances out of the water. Shortfin Mako sharks have a better hydrodynamic shape than other sharks, powerful muscles and are warm blooded. Its speed has been recorded at 31 mph and it can leap up to 9 meters. It is likely that it can achieve much faster speeds than this in short bursts.
The Shortfin Mako gives birth to live young who feed from a sac full of yolk in the womb. The gestation period for a Mako shark is 15 to 18 months. The embryos consume each other within the female's body to get nutrients. This extremely rare cannibalistic trait is called ovophagy. The 4-18 surviving young are born at a length of about 70cm.
125p Whale Shark
Growing to over 12 meters and weighing over 20 tons, the whale shark is the largest living fish species. It is found in tropical and warm oceans and lives in the open sea. The species is believed to have originated about 60 million years ago.
It is found to depths of 700 meters, is solitary and rarely seen in groups unless feeding at locations with an abundance of food. It is a slow filter feeding shark that has a capacious mouth which can be up to 1.5 meters wide and can contain between 300 and 350 rows of tiny teeth. It does not need to swim forward when feeding as it is able to pump the water through its gills.
This distinctively marked shark's skin has yellow spots and stripes that are unique to each shark. Despite its enormous size it does not pose any significant danger to humans who avoid its large tail.
The eggs remain in the body and the females give birth to live young, which are 40-60cm long. It is believed that they reach sexual maturity at around 30 years and the life span has been estimated to be over 100 years.
150p Bigeye Thresher
The Bigeye Thresher is found in warm, temperate and tropical oceanic and coastal waters from the surface to depths of 152 meters. Found nearly worldwide Bigeye Threshers occasionally enter shallow waters near land but generally are found in the open sea.
Named after an enormous upward looking eye set high in its head, suggesting a deepwater preference, the Bigeye Thresher is also characterized by an enormous long upper caudal lobe which can be as much as 50% of its entire length of around 400cm. This species is also ovophagous (whereby sibling foetuses eat each other before birth). Usually 2 pups survive and are born in open water. It is considered harmless to humans.
The First Day Cover depicts the Galapagos shark, which can be found in warm tropical waters at depths ranging from 5 to 60 meters. Their average length is around 3 meters. They hunt prey from the sea floor. Adult Galapagos sharks are also cannibalistic, eating their own young if encountered.
Its distribution is widespread but patchy with populations occurring at many widely separated island sites and also in some coastal areas in the Pacific, Atlantic and Indian oceans. It seems that there is little or no migration between these populations. It is classed as "Near threatened" because it may be subject to high levels of fishing pressure in many areas of its range.
Postage stamps in detail
Issue: Ascension Island, 14 March 2008
Designer: Nick Shewring
Print: lithography by BDT International
Perforation: 14 per 2cms
Stamp size: 28.45 x 42.58mm
Souvenir sheet size: 45 x 70mm
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