Dolphins

One of the most intelligent animals in the world, second only to human - report suggests.

 

Common Name - Dolphins.

 

Scientific Name - Odontoceti

 

Size - upto 32 feet

 

Weight - upto 6 tons

 

IUCN - Least concern

 

Dolphins are ‘small toothed cetaceans’ that are easily recognized by their curved mouths, which give them a permanent "smile". There are 36 species of dolphins, which are found in all oceans. Most dolphins are aquatic and live in oceans or brackish waters near coastlines. However, there are a few species, such as the ‘South Asian river dolphin’ and the ‘Amazon River dolphin’, or ‘boto’, that live in streams and rivers (freshwater).

 

The largest dolphin, the ‘’Orca’’, can reach over 30 feet in length. The smallest, the ‘’Maui’’ Dolphin, is only five feet long.

 

Dolphins feed mainly on fish and squid, which they follow using ‘echolocation’, a built-in sonar that emits sound waves off prey and reveals information such as their location, size and shape. A ‘bottle-nose’ dolphin can produce up to a thousand clicking noises per second. 

 

Living in pods that can number a dozen or more, dolphins are highly sociable animals that communicate through squeaks, hisses and clicks. Whether dolphins have language, like humans, is a topic scientists have debated for decades. Like mammals, they are passionate about raising their young and are warm blooded. Dolphins have more than one mate and usually give birth to one cub that stays with its mother for up to six years, depending on the species.

 

Dolphins are beautiful and graceful swimmers that can reach more than 18 miles per hour. They play and often dance after the boat, jumping out of the water, maybe for fun, to chat, or even to get rid of bad germs. 

 

For centuries, humans have hunted dolphins for their meat and blubber. Today, their main source of fear comes from being accidentally caught in commercial fishing nets. Dolphins will often come to the surface to breathe - entering the net prevents this, leading to drowning. For ‘’Maine dolphins’’, warming ocean temperatures due to climate change have caused some of their food sources to move into deeper, colder waters. In addition, water heat waves, also caused by climate change, seem to have a negative effect on dolphin reproduction rates and survival.

In addition to hunting and involvement in fishing gear, freshwater dolphins face the added threat of dams destroying and damaging habitats. 

 

Dolphins are known to teach, learn, cooperate, plot, and mourn. The neocortex of many species is home to elongated spindle neurons that, before 2007, were known only in hominids. In humans, these cells are involved in social behavior, emotions, judgment, and cognitive function. Cetacean spindle neurons are found in areas of the brain that are similar to those found in humans, suggesting that they perform a similar function.

 

Brain size has long been regarded as a key indicator of animal intelligence. Since most of the brain is used for maintaining the functions of the body, ratio of the size of the brain to body size can increase the amount of brain mass available for complex tasks. Allometric analysis shows that the brain size of mammals is about ⅔ or ¾ of the body measurements. Comparing the brain size of a particular animal with the expected brain size based on such allometric analysis provides an encephalization rate that can be used as another indicator of animal intelligence. 

 

The killer or Orcas whale has the second largest brain of any animal on Earth, after the ‘’sperm whale’’. The brain to body mass ratio found in some is twice that of humans.

 

Some people consider self-awareness to be a sign of a highly developed subconscious mind. Self-awareness, although not well defined in science, is considered as something that will lead to higher processes such as metacognitive thinking (thinking about thinking) that is common in humans. Research in this area has shown that cetaceans, among others, have self-awareness. 

 

The most commonly used test for self-awareness in animals is the mirror test in which a mirror is placed in front of the animal and the animal is marked with  temporary dye. If the animal goes to the mirror to see the mark, it shows strong evidence of self-awareness.

 

Some disagree with these results, arguing that the results of these tests are open to human interpretation and can be influenced by ‘Clever Hans effect’. This test is less detailed than when used for primates, since primates can touch signs or mirrors, while cetaceans cannot, making their alleged self-identification behavior uncertain. 

 

Skeptics argue that these self-identified behaviors are similar to real social behaviors, so researchers can misinterpret the self awareness for a social response to another. The researchers say that these behaviors are evidence of self-awareness, because they are very different from the normal response to another individual. Although monkeys can use their fingers to touch the marks on their own bodies, cetaceans show less definitive behavior of self awareness; they can only twist and turn to see the sign.

 

In 1995, Marten and Psarakos used television to test dolphins' self-awareness. They showed the dolphins live videos of themselves, videos of other dolphins, and recorded videos. They concluded that their evidence shows that they are known for their self awareness rather than social behavior. Although this study has not been repeated since then, dolphins have passed the mirror test. Some researchers have said that there has not been any clear evidence of self-awareness.

 

A group of dolphins is called a ‘school’ or a ‘pod’. Male dolphins are called ‘bulls’ females called ‘cows’ and young dolphins are called ‘calves’.