Interesting Dolphin Facts and Information
In general when talking about dolphins, people are usually referring to the Bottlenose dolphin. However, there are in fact over 30 different kinds of dolphin. Different sources state there are either 32 or 33 types. Plus there are a further 6 different kinds of porpoises, and 5 different freshwater dolphins who live in rivers.
The smallest dolphins include Hectors Dolphin (1.2m to 1.5m) and Black dolphin (1.2m to 1.7m). The largest dolphin is the Orca, also known as the Killer Whale, which can grow up to 9.6m in length (31.5 feet). The Orca can weigh over 4 and a half tonnes.
Whilst both dolphins and porpoises are in the same scientific order, both being Cetaceans, Porpoises are in the family Phocoenidae whereas dolphins are in the family Delphinidae. The main differences between dolphins and porpoises are that most dolphins have a very prominent beak, also known as a rostrum, whereas porpoises lack this physical feature, and have a giving more rounded shape of head. Porpoises have smaller, dumpy-ish bodies unlike the lean sleek look of dolphins. The dorsal fins on the backs of the animals are different too: dolphins have a hook-shaped or wave-shaped dorsal fin, whereas porpoises have a triangular dorsal fin. Also there is a difference on the teeth: dolphins have pointed conical teeth whereas the teeth of porpoises are spatula or spade-shaped.
Dolphin lifespan is normally between 20 to 40 years, with some reports of a possible 50 year lifespan or even longer.
The brain size of a Bottlenose dolphin is sightly larger than that of a human. The average brain weight for the Bottlenose is 1600 grams wheras a human is only 1500 grams. Brain size as an absolute figure, or brain weight as a percentage of overall total body weight, is not thought to be a definite indicator of absolute intelligence. A mouse, for example, devotes a larger percentage of its body weight to its brain than does a human.
Some researchers have suggested that an important measure of intelligence is the size and complexity of the brain at birth. This is an extremely positive indicator for dolphin intelligence. Bottlenose dolphins start life with particularly large brains: at birth they have a brain mass which is 42.5% of that of an adult human. Humans at birth only have 25% of adult human brain mass. By the age of 18 months, the brain mass of Bottlenose dolphins is roughly 80% of that of an adult human. In general, human beings generally do not achieve this figure until the age of three or four years old.
One thing is certain - behavioural monitoring and interaction with dolphins does show a definite high degree of intelligence. Whether they could be described as equally intelligent or even smarter than us humans isn't quite certain yet.
The dolphin's neural area devoted to visual imaging is only about one-tenth that of the human brain, while the area devoted to acoustical (sound) imaging is about 10 times that of the human brain.
Dolphins also rely on sounds called “echolocation clicks” to navigate through the water and to help them locate prey. The sound is received through their lower jaw. The clicks and whistles are also thought to be a way of communicating with other dolphins.
They can also use their sophisticated sound system as a weapon when fishing for food. Dolphins have been observed to stun fish with sound blasts from their inbuilt acoustic system. They have also been recorded emitting medium frequency buzzing noises which has been seen to cause buried eels to jump out of the sand and either stop moving or become sluggish as if stunned.
Interestingly, dolphins have little or no sense of smell at all. Olfactory lobes of the brain, necessary for processing smells, and olfactory nerves are absent in all toothed whales. It is though that they can taste, as they do have taste buds.
The average dolphin eats about 8 to 15 kilograms (15 to 30 pounds) of food each day. They mainly like to eat fish, for example mullet, tuna, snapper and pinfish, and they also eat squid as well.
A group of dolphins is known as a pod or a school. The size of a pod can vary significantly. Older male Orca tend to lead reasonably solitary lives but this is the exception. River dolphins usually congregate in fairly small groups, from 6 to 12 in number. In the sea, a mother and her child may swim together on their own, or be part of a pod of up to 15 dolphins. Pods can often join together, and 500 dolphins or more may sometimes swim together. Dolphins live in every ocean in the world.
A male dolphin is known as a Bull, and a female is known as a cow. A baby dolphin is known as a calf. Dolphin mothers start producing calfs when the mothers are 5 to 10 years old, and can continue having calfs up to 40. Adult females produce a single new calf about every 3 to 6 years. Gestation period (the time a calf spends in its mothers womb between fertilization and birth) is 12 months for bottlenose dolphins. The calf is born tail first, and swims to the surface, assisted by its mother and helper female dolphins, to take its first breath of air as soon as it is born. At birth, a bottlenose dolphin calf is approximately 90 to 130 centimeters in length and about 30 kilograms in weight. The mother will feed the calf until the age of 2 years old. As a calf grows older, it gradually starts to to spend more time playing with other young dolphins. However, the calf will remain with its mother until the age of around 3 to 6 years old.
Dolphins are not fish, but are warm-blooded mammals.
They need air to breathe, and must do this at the water's surface. The blow-hole at the top of their heads acts like a nostril, and enables them to breathe at the surface. On average they come to the surface two or three times a minute, but can hold their breath for 5 to 8 minutes if necessary. The time taken to breathe out and in is less than a third of a second. During this time, the dolphin will exchange 80 percent or more of its lung capacity. This is much far more efficient than humans, who exchange only about 17 percent of the air in their lungs with each breath. As a result of such a large amount of air being exchanged in such a small amount of time, the dolphin produces from its blowhole an explosive cloud known as a blow, the air of which can travel at speeds of over 100 mph. When underwater, they close their blowhole to ensure that water doesn't get into their lungs.
Because they must consciously come to the surface for air, dolphins they never fall into a deep sleep. Instead, they sleep in light naps, in a semi-conscious state, resting one side of the brain for a short time. These naps may last for several minutes every couple of hours, during which time they slowly rise to the surface to catch a breath of air and then fall below. Usually they have one eye closed, or their eyes will open a little bit every now and then during the nap.
Dolphins are well-known for their agility and playful behavior. Many species will leap out of the water, and spy-hop (rising vertically out of the water to view their surroundings). They can dive to a depth of over 1,000 feet (300 m) and can jump up to 20 feet (6 m) high out of the water. They normally swim at just a few miles per hour, but they can achieve speeds up to 25 miles per hour (40 Km/h).
They will often follow ships, synchronizing their movements with that of the sailing craft. Scientists believe that by swimming alongside ships, known as bow-riding, dolphins conserve energy. As a result of their willingness to approach sailing craft and humans, in some cultures like Ancient Greece they were treated with great welcome. For example, dolphins riding in a ship's wake was considered a good omen for a smooth voyage.
Read fascinating info about The Baiji Dolphin of the Yangtze River in China, which is the rarest mammal in the world.
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