Thursday 29 July 2010 The Pantropical Spotted Dolphin - Yellow Fin Tuna's Best Friend

The pantropical spotted dolphin (Stenella attenuata) is a species of dolphin in the genus Stenella and is one of the more distinctive species of dolphin in the world's oceans. When the pantropical spotted dolphin is born it can be hard to distinguish it from its cousin the common bottlenose dolphin as they are without spots. The dolphin acquires spots as it matures until the body is eventually covered with overlapping patterns of spots. When the pantropical spotted dolphin reaches maturity the body has a distinct black "cape" down its back with gray along the sides and a white underbelly. The pantropical spotted dolphin, like many of the other species in the Stenella genus, is a smaller dolphin. The average dolphin grows to between 1.5-2 meters (6-7ft) in length and weighs around 114 kg (250lbs).

It is possible to mistake the pantropical spotted dolphin with the coastal spotted dolphin and Atlantic spotted dolphin. However, the coastal dolphin is a subspecies of the pantropical spotted dolphin while the Atlantic dolphin is a different species in the Stenella genus. It is often hard to differentiate between the varieties as their coloration is very similar, but the pantropical spotted dolphin is often slightly smaller at full maturity and is found in a wider stretch of ocean.

The pantropical spotted dolphin is found in tropical and sub-tropical oceans and waterways across the globe. Their distribution can vary widely with some stocks occurring in and around the Hawaiian Islands, while others are found in large numbers far at sea in the Eastern Pacific Ocean. During the daytime hours spotted dolphins can be found in shallow waters with depths between 90-300 m (300 to 1,000 ft), but dive into deeper water at night in search of food. The dolphin feeds on a variety of creatures including fish, such as mackerel and flying fish, squid, and shrimp.

The pantropical spotted dolphin is unique for its unexplained association with yellow fin tuna. In fact, the species gained international notoriety in the late 1970s and 1980s as the species was pushed to the brink of annihilation due to their association with the yellow fin tuna. As fishermen around the globe used purse-seine nets to trap the tuna, they would trap the dolphins in their nets as well, leading to suffocation of the dolphins. An intense focus on dolphin-safe tuna fishing standards in the United States has helped bring the pantropical spotted dolphins' numbers back up, but its association with the yellow fin tuna and questionable fishing habits by mankind remain the biggest threats to the pantropical spotted dolphin. You can help spreading the word about this animal by liking it on facebook

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Friday 23 July 2010 The Great White Shark: Nature's Most Fearsome Hunter

The great white shark (Carcharodon carcharias), although it's more commonly known as 'great white' or 'white death'. The great white is one of the most fearsome hunters on the planet and is known primarily for its size, which can be up to 6 metres (20 feet) or more with a weight of over 2,240 kilograms (4,938 pounds). The great white shark is the only surviving member of its genus, Carcharodon.

An interesting thing about great white sharks is their distribution. Great whites currently inhabit virtually all coastal waters with temperatures between 12 and 24 degrees Celsius, or 54 and 75 degrees Fahrenheit. Typically, however, great whites tend to congregate in high numbers around Australia, California, the northeastern United States, South Africa, New Zealand, Isle Guadalupe of Mexico and the Mediterranean waters. In fact, the densest population of sharks is found off the coast of Dyer Island of South Africa and it's here that most great white research takes place.

Currently, the social behavior and structure of great whites is not well known. Studies on populations in South Africa show a dominance hierarchy, which depends on a number of things like size and gender. Female great whites dominate males and area residents display dominance over newcomers to the area.

The diet of the great white shark is very diverse and they will prey upon everything from fish, cetaceans, pinnipeds, sea turtles, sea birds and sea otters. Popular prey includes tuna fish, rays, other sharks, dolphins and whales and especially sea lions, and seals. Great white sharks also have a reputation for consuming inedible objects like license plates and cans, which can often be found in the bellies of these sharks when they're caught. One reputation that the great white has not earned is as an "eating machine." Great whites are ambush hunters, choosing to take their prey from below. Their hunting style also seems to vary depending on their prey. For example, they prefer to attack seals at such high speeds near the surface of the water that they'll actually completely leave the water's surface. Dolphins, on the other hand, are usually attacked from above or behind to avoid their echolocation. In the wild, great whites are known as apex predators, meaning they have virtually no enemies other than the killer whale on occasion.

Great whites became infamous after their depiction in the 1975 movie Jaws, portraying the shark as a man eater. Fortunately, great whites very rarely attack and kill humans, and are not likely to even target them for attack. In the densely populated Mediterranean Sea, for example, there have only been 31 confirmed attacks on humans in the last two hundred years and most of these attacks were non-fatal. It's believed that attacks on humans are merely a case of mistaken identity as the shark probably sees a swimmer from below as a seal. Great whites are currently considered a vulnerable species, although it's not known exactly how large their population is. Still, conservation efforts are in place to protect the great white from hunting.

Picture of the great white shark by Terry Goss, licensed under GFDL You can help spreading the word about this animal by liking it on facebook

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