It's always interesting to discuss the extremes of nature; be it the largest flower, the Rafflesia, or the largest animal, the blue whale. Behind their profound size, there are hidden adaptation strategies. While small animals have the advantage of hiding and escaping their enemies, these large animals use their enormous size to ward off their enemies. Which is the Largest Animal in the World? Animals are classified into different groups, like insects, birds, reptiles, amphibians, and mammals. You can find the largest species for each of these groups. When we say the 'largest animal' though, it refers to the one that looks enormous in size and weighs the most, regardless of which group it belongs to, and that title goes to a mammal, the blue whale (Balaenoptera musculus). In spite of the fact that it is found in the marine habitat, blue whale is a mammal. It gives birth to young ones. Lengthwise, an adult blue whale may measure anywhere between 23 to 30.5 meters (75 to 100 feet) from head to tail and weighs about 136 metric tons (150 tons). Its weight is equivalent to the collective weight of 1,500 men or 24 elephants. Its heart is as big as a car (more than 1-meter long). It is said that more than 50 people can stand on the blue whale's tongue. Additionally, the blue whale also holds the title for the loudest animal on the Earth. What about the African Elephant? The African bush elephant (Loxodonta africana) boasts of being the largest land animal in the world. An adult male grows to about 13 feet in height and 20 feet in length. It is also the second tallest land animal, preceded by giraffe. The weight of a full-grown African elephant is approximately 7 - 8 tons, which equals the weight of 165 adult men. The African species is bigger than its Asian counterpart. The size of an elephant is more or less similar to that of a baby blue whale, measuring about 20 feet in length. Other Large Animals by Categories

• Fish: Whale shark (Length: 13.6 m, Weight: 24 tons)
• Reptile: Saltwater crocodile (Length: 5 m, Weight: 2.1 tons)
• Bird: Ostrich (Height: 2.1 m, Weight: 156 kg)
• Amphibian: Chinese giant salamander (Length: 1.83 m, Weight: 64 kg)

Last, but not the least, the biggest carnivorous animal in the world is the polar bear, with a height of 3 meters and weighing about a ton. There was a time, when the population of blue whales was 200,000. With increased hunting, it has declined to just 10,000, as a result of which, they are now enlisted as endangered species in the Red List compiled by the International Union for Conservation of Nature (IUCN).