Wednesday, September 14, 2011

DIFFERENT ASPECTS OF DOLPHIN LIFE

DOLPHINS 
 HOW DEEP CAN A DOLPHIN DIVE?
The deepest dive ever recorded for a bottlenose dolphin was a 300 meters (990 feet). This was accomplished by Tuffy, a dolphin trained by the US Navy. Most likely dolphins do not dive very deep, though. Many bottlenose dolphins live in fairly shallow water. In the Sarasota Bay area, the dolphins spend a considarable time in waters that are less than 2 meters (7 feet) deep.
Other whale and dolphin species are able to dive to much greater depths even. The pilot whale (Globicephala melaena) can dive to at least 600 meters (2000 feet) and a sperm whale (Physeter macrocephalus) has been found entangled in a cable at more that 900 meters (500 fathoms) depth.
A recent study on the behaviours of belugas (Delphinapterus leucas) has revealed that they regularly dive to depths of 800 meters. The deepest dive recorded of a beluga was to 1250 meters
HOW LONG DO DOLPHINS LIVE?
The maximum age for bottlenose dolphins is between 40 and 50 years. The average age a dolphin can get (the life expectancy) can be calculated from the ASR Annual Survival Rate (the percentage of animals alive at a certain point, that is still alive one year later). For the dolphin population in Sarasota Bay, the ASR has been measured to be about 0.961. This yields a life expectancy of about 25 years. For the population in the Indian/Banana River area, the ASR is between 0.908 and 0.931. This yields a life expectance between 10.3 and 14 years. So the actual life expectancy differs per region.

SOURCES:
[3] R.S. Wells and M.D. Scott (1990) Estimating bottlenose dolphin population parameters from individual identification and capture-release techniques. Report International Whaling Commission (Special Issue 12): 407-415
[3] S.L.Hersch, D.K.Odell, E.D.Asper (1990) Bottlenose dolphin mortality patterns in the Indian/Banana River System of Florida, in S. Leatherwood and R.R. Reeves: The Bottlenose Dolphin, pp. 155-164, Academic Press.
HOW MUCH DO DOLPHINS EAT?
Bottlenose dolphins eat several kinds of fish (including mullet, mackerel, herring, and cod) and squid. The composition of the diet depends very much on what is available in the area they live in and also on the season. The amount of fish they eat depends on the fish species they are feeding on: mackerel and herring have a very high fat content and consequently have a high caloric value, whereas squid has a very low caloric value, so to get the same energy intake (calories) they will need to eat much more if they feed on squid than if they feed on mackerel or herring. On average an adult dolphin will eat 4-9% of its body weight in fish, so a 250 kg (550 lb) dolphin will eat 10-22.5 kg (22-50 lb) fish per day.
HOW SMART ARE DOLPHINS?
The short answer to this is that we do not know. There is no reliable method to measure intelligence in humans across cultures, so it is not surprising that comparing humans, dolphins, apes, dogs, etc. is impossible. There are some indications of their potential: they are fast learners and can generalize (which is also true of pigs). Also they can learn to understand complicated language-like commands (which is also true of the great apes)
HOW DO DOLPHINS SLEEP?
DOLPHINS HAVE TO BE CONSCIOUS TO BREATH.

This means that they cannot go into a full deep sleep, because then they would suffocate. Dolphins have "solved" that by letting one half of their brain sleep at a time. This has been determined by doing EEG studies on dolphins. Dolphins sleep about 8 hour’s day in this fashion.

A dolphin's behaviour when sleeping/resting depends on the circumstances and possibly on individual preferences. They can either:
1. 1 swim slowly and surface every now and then for a breath
2. 2 rest at the surface with their blowhole exposed
3. Rest on the bottom (in shallow water) and rise to the surface every now and then to breathe.
SOURCES:
[1] Williams et al, 1990
[2] S.H Ridgway (1990) The Central Nervous System of the Bottlenose Dolphin, in S. Leatherwood and R.R. Reeves: The Bottlenose Dolphin, pp. 69-97, Academic Press
EVOLUTION AND ANATOMY?
Dolphins, along with whales and porpoises, are descendants of terrestrial mammals, most likely of the Artiodactyl order. The ancestors of the modern day dolphins entered the water roughly fifty million years ago, in the Eocene epoch.
Hind Limb Buds on Dolphins. An embryo of a Spotted Dolphin in the fifth week of development. The hind limbs are present as small bumps (hind limb buds) near the base of the tail. The pin is approximately 2.5 cm (1.0 in) long.
Bottlenose Dolphin with vestigial hind flippers, captured 2006 in Japan

Modern dolphin skeletons have two small, rod-shaped pelvic bones thought to be vestigial hind limbs. In October 2006 an unusual Bottlenose Dolphin was captured in Japan; it had small fins on each side of its genital slit which scientists believe to be a more pronounced development of these vestigial hind limbs.
ANATOMY
Dolphins have a streamlined fusiform body, adapted for fast swimming. The tail fin, called the fluke, is used for propulsion, while the pectoral fins together with the entire tail section provide directional control. The dorsal fin, in those species that have one, provides stability while swimming.

Though it varies per species, basic colouration patterns are shades of grey usually with a lighter underside. It is often combined with lines and patches of different hue and contrast.

The head contains the melon, a round organ used for echolocation. In many species, the jaws are elongated, forming a distinct beak; for some species like the Bottlenose, there is a curved mouth which looks like a fixed smile. Teeth can be very numerous (up to two hundred and fifty) in several species. Dolphins breathe through a blowhole located on top of their head, with the trachea being anterior to the brain. The dolphin brain is large and highly complex and is different in structure from most land mammals.

Unlike most mammals, dolphins do not have hair, but they are born with a few hairs around the tip of their rostrum which they lose shortly after birth, in some cases even before they are born. The only exception to this is the Boto river dolphin, which does have some small hairs on the rostrum.

Their reproductive organs are located on the underside of the body. Males have two slits, one concealing the penis and one further behind for the anus. The female has one genital slit, housing the vagina and the anus. A mammary slit is positioned on either side of the female's genital slit.

SENSES

Most dolphins have acute eyesight, both in and out of the water, and their sense of hearing is superior to that of humans.[citation needed] Though they have a small ear opening on each side of their head, it is believed that hearing underwater is also if not exclusively done with the lower jaw which conducts the sound vibrations to the middle ear via a fat-filled cavity in the lower jaw bone. Hearing is also used for echolocation, which seems to be an ability all dolphins have. It is believed that their teeth are arranged in a way that works as an array or antenna to receive the incoming sound and make it easier for them to pinpoint the exact location of an object.[11] The dolphin's sense of touch is also well-developed, with free nerve endings being densely packed in the skin, especially around the snout, pectoral fins and genital area. However, dolphins lack an olfactory nerve and lobes and thus are believed to have no sense of smell,[12] but they can taste and do show preferences for certain kinds of fish. Since dolphins spend most of their time below the surface normally, just tasting the water could act in a manner analogous to a sense of smell.

Though most dolphins do not have any hair, they do still have hair follicles and it is believed these might still perform some sensory function, though it is unclear what exactly this may be.[13] The small hairs on the rostrum of the Boto river dolphin are believed to function as a tactile sense however, possibly to compensate for the Boto's poor eyesight.
A SHORT HISTORY OF DOLPHINS
Dolphins are magical creatures that have been on Earth for SOME 25 million years, according to fossil evidence. The first recorded studies of dolphins and dolphin behavior was undertaken by the ancient Greek philosopher Aristotle (384-322 BC) in Historia Animalium, (The History of Animals). Aristotle was the first to correctly claim that dolphins were mammals. He observed that they bore their young alive and suckled them, breathed air and communicated by underwater sounds.

Through the ages, people and dolphins have had a special bond. There are many well-documented stories throughout history of ancient mariners who were guided to safety by dolphins. Dolphin insignias were commonly used on ancient ships for protection. Ancient artifacts show dolphins being used in decorative ways. Prehistoric engraved images of dolphins have been found in South Africa. One shows a man swimming with dolphins. At the palace of Knossos, an Aegean civilization, the bathroom of the queen was decorated with a frieze of dolphins. This palace is dated at 1600 BC. Dolphins have been found on funeral frescoes dated from the sixth century BC. Greeks decorated their ceramics with dolphin images in the fifth century BC. Forty Greek cities had images of dolphins on their coins.

The Roman historian, Pliny the Elder, tells the story of a boy who rode on the back of a dolphin called Simo. Roman coins dated at 74 BC depict this dolphin scene. There is a similar story from Greece about a dolphin named Lassos, who fell in love with a boy and took him far out to sea for dolphin rides. As recently as October 2000, it was reported that a small boy drowning off the coast of Italy was rescued and brought ashore by a dolphin.

In mythology, it is said that Apollo first appeared at Delphi, the site of the oracle, in the form of a dolphin. In Greek, Delphi means dolphin. Taras, son of Neptune, founded a city called Tarento on the pot he was carried to safety by a dolphin. It is also said that Telemachus, son of Ulysses, fell into the water as a child. He was rescued by dolphins. Thereafter, Ulysses wore a ring engraved with the image of dolphins. The dolphin was sacred to the Greeks, and they would never dream of harming a dolphin.

Plutarch, around 75 AD, told the story of Korianos, a native of Asia Minor. Korianos pleaded for the life of a dolphin who was caught in a fishing net. The dolphin was saved. Later, Korianos was shipwrecked and his life was saved by a dolphin.

Throughout history, there are stories told of the relationship between dolphin and man, particularly of dolphin helping man catch fish. Oppian, a Greek poet of the second century AD, told stores of dolphins pushing fish into the nets of fishermen.

The aborigines of Australia have had many connections to dolphins. The natives of Amity Point in Moreton Bay called the dolphins to them to help them with fishing. The people would sit on a hill waiting to spot mullet. When they saw a school they ran to the water and splashed the water with their spears. This action called the dolphins who would swim in and block the retreat of the mullet, thus allowing the natives to catch all the mullet they could use. And the dolphins shared the mullet.

In the northern part of Australia there is an island in the Gulf of Carpentaria called Groote Eylandt. The natives there consider themselves to be the direct descendants of dolphins. The dolphin is celebrated in their stories and ceremonies.

There is another aborigine tribe living on Mornington Island in the Gulf of Carpentaria who calls themselves the Dolphin People. Young boys go through a series of tests as they grow up in order to determine their sensitivity and intuition. The most sensitive boy will become the tribal shaman. The Dolphin People believe the shaman is a dolphin spirit who has chosen to reincarnate in the form of a man. The shaman performs a complex series of whistles designed to bring the dolphin closer to shore. When the shaman stops whistling, he makes a mind-to-mind connection with the dolphins.

To the Maoris of New Zealand, the dolphin is sacred. Authors Amanda Cochrane and Karena Callen, in their book Dolphins and Their Power to Heal, quote one Maori elder who described dolphins as being a "human being in the sea." They are only to be called upon in very difficult times.

The Polynesian people of the Gilbert Islands called dolphins to them. They would enter a dream-like state and then seek the dolphins out in their homes. They would invite the dolphins to a feast in the village. If the invitation were worded correctly, the dolphins would swim into the bay. The Gilbert Islanders then rushed into the water and dragged the dolphins onto shore whereupon the dolphins became the main course at the feast. The natives believed that the dolphins who came did so voluntarily with the knowledge that their bodies would be used to nourish the islanders.

In Native American traditions, dolphins symbolized manna or life force. It was thought that the dolphin was the "keeper of the sacred breath of life and was a healing totem used to release emotional tension" (from Dolphins and Their Power to Heal). Totem Power Stones say a dolphin is indicative of kindness, play, and is the bridge between man and ocean.

Dolphins are the symbol of rebirth. Christ is sometimes represented in the form of a dolphin.

So, what is it about dolphins that strike such a chord in humans? We view dolphins in anthropomorphic terms. Dolphins love to play and seem to take great joy in the playing. We would say that dolphins live in the moment. They are compassionate, caring, loving and gentle. Dolphins will assist ailing dolphins to the surface so that they can breathe. They have never been known to attack man in the wild. They get annoyed with each other, but always appear to reach a settlement of a dispute quickly and don't appear to hold grudges. They are highly intelligent. They are beautiful and graceful in the water. Some say we are so attracted to dolphins because they embody the qualities we want in ourselves. As Rosie O'Donnell said on one of her programs, "It's such a magical, mystical thing when you see dolphins."


In the animal kingdom there are many different groups or "classes" such as reptiles, birds, amphibians and mammals. All mammals have five characteristics in common:

Warm-blooded
Breath air
Give birth to live young
Born with hair
Nurse their young

Dolphins are one of many marine mammals that inhabit the sea, others being manatees, otters, sea lions and whales.

All the whales, dolphins and porpoises belong to the order called Cetacea, which can be further divided into three smaller groups known as suborders. The Archeocetes were the ancient whales and are now extinct. The second group, the Mysticetes, include, among others, the gigantic blue, grey and humpback whales. Members of this suborder have two blowholes and instead of teeth, have a series of comb-like plates called baleen which they use to strain plankton and shrimp from the water as a food source.

The largest suborder is the Odontocetes , also known as the toothed whales which includes groups such as the sperm whales, belugas and dolphins. The number of teeth may vary with the species, but all use their teeth for catching, not chewing, their food. There are ten different families of toothed whales.

Though many people often confuse the two, dolphins and porpoises are different families of toothed whales. Divided into six different species, porpoises are generally smaller than dolphins, darker in colour, and found in deeper and cooler waters. Porpoises usually lack the rostrum or "bottlenose" that most dolphins have. Another distinct trait of porpoises is their teeth: they have flat, spade-shaped teeth versus the conical-shaped teeth of dolphins.

Finally, there are about thirty species of dolphins found in our oceans, a few being the white-sided, spotted and bottlenose. It is the Atlantic bottlenose dolphin, Tursiops truncatus, which is most well known to people.

These animals tend to live in the shallow waters in which people frequently choose to swim and boat. This species of dolphin also does very well under human care and are usually your marine park performers.

ATLANTIC BOTTLENOSE DOLPHINS
The Atlantic bottlenose dolphin can be found throughout the temperate, tropical and sub-tropical waters of the Atlantic Ocean. With a great deal of variety in size, appearance and behaviours, these dolphins are further divided into approximately nine different sub-species. For example, the bottlenose dolphins off the United Kingdom may weigh up to 1200 pounds and migrate short distances to locate food or evade predators. In the shallow Bahamian waters, Atlantic bottlenose dolphins grow up to nine feet in length weighing up to 500 pounds. Average lifespan for this species in the wild is approximately 30 years.

Research confirms that these animals currently live equally as long under human care and, in many cases, live longer, healthier lives than their counterparts in the wild. In marine parks and aquariums, dolphins are protected from the dangers of pollution, predators, and events such as El Nino, which triggered food shortages for many marine mammals in the late 1990’s. The oldest dolphin under human care lived to be 48 years of age. Due to public display, advances in animal care and medicine have greatly contributed to the improved health of cetaceans under human care, as well as to the successful rehabilitation and release of stranded, injured animals.

In general dolphins are well known for their bottlenose or rostrum with the built-in smile. The rostrum is a bony extension of their skull used to touch and move objects since they don’t have hands. The hair on a dolphin’s upper rostrum - a "mustache" of sorts - falls out either just before the animal is born or shortly thereafter.

Inside the mouth, 88 to 120 conically-shaped teeth can be found. Remember, dolphins do not chew their food. The teeth are used to grasp prey before swallowing it whole. The stomach of a dolphin is highly acidic, capable of digesting whole foods. As far as diet, these dolphins are known as "catholic" feeders, eating whatever fish species is locally available. Primarily they eat schooling fish - herring, mackerel, mullet or capelin to name a few - but also some crustaceans and molluscs, such as squid or shrimp.

VOCALIZATIONS
The blowhole on top of the dolphin’s head is their nose. Dolphins can remain submerged up to 8 minutes but generally take a breath about every 30 seconds. In fact the blowhole is the only place they breathe. The blowhole, not the mouth, is also the only place from which sounds come. Beneath the opening of the blowhole are three pairs of nasal air sacs and by squeezing air from one sac to another, dolphins produce sounds. Vocalizations are broken down into three main types: buzzes, clicks and whistles.
CAUGHT ON CAMERA: IS THIS THE WORLD'S ONLY PINK DOLPHIN?

These are the stunning pictures of a rare pink bottlenose dolphin spotted swimming in a Louisiana lake. The mammal was pictured by local charter boat captain Erik Rue, who has been studying the dolphin since it first surfaced in Lake Calcasieu, an inland saltwater estuary, north of the Gulf of Mexico in Southwestern USA.

Since it was spotted with its pod of normal coloured dolphins last year the animal has been wowing visitors on the lake. Capt Rue, 42, originally saw the dolphin, which also has reddish eyes, swimming with a pod of four other dolphins, with one appearing to be its mother which never left its side.

Stunning sight: The rare albino dolphin has been spotted by excited visitors to Lake Calcasieu in Louisiana

'I just happened to see a little pod of dolphins, and I noticed one that was a little lighter. It was absolutely stunningly pink', he said.

'I had never seen anything like it. It's the same colour throughout the whole body and it looks like it just came out of a paint booth. The dolphin appears to be healthy and normal other than its colouration, which is quite beautiful.

'The mammal is entirely pink from tip to tail and has reddish eyes indicating its albinism. The skin appears smooth, glossy pink and without flaws. I have spotted it about 40 to 50 times in the time since the original sighting as it has apparently taken up residence with its family in the Calcasieu Ship Channel. 'As time has passed he has grown and sometimes ventures away from its mother to feed and play but always remains in the vicinity of the pod. Surprisingly, it does not appear to be drastically affected by the environment or sunlight as might be expected considering its condition, although it tends to remain below the surface a little more than the others in the pod.'

The striking mammal is thought to be the world's only pink bottlenose dolphin. Capt Rue added: 'I feel very fortunate to have seen this incredible mammal and lucky to be able to work and live in the area where such a fantastic creature frequents.

'Our guests are always thrilled at the opportunity to spot such a unique mammal and we look forward to it being around for some time to come.'

Regina Asmutis-Silvia, senior biologist, with the Whale and Dolphin Conservation Society, called the dolphin 'truly beautiful'.

'I have never seen a dolphin coloured in this way in all my career', she said.

'While this animal looks pink, it is an albino which you can notice in the pink eyes. Albinism is a genetic trait and it unclear as to the type of albinism this animal inherited.

'It is a truly beautiful dolphin but people should be careful, as with any dolphins, to respect it. Observe from a distance, limit their time watching, don't chase or harass it.


Source: http://www.dailymail.co.uk/news/arti...K-dolphin.html
DOLPHIN MAKES FRIENDS WITH TIGER!



Like a cat peering into a goldfish bowl, Akaasha the tiger cub is transfixed by a dolphin staring back at her.

Curiosity got the better of both Akaasha and Mavrick, a 14-month-old dolphin who's probably more used to a crowd of human faces gazing into his glass tank at a Californian theme park.

Staff was taking six-month-old Akaasha on her daily walk around the Six Flags Discovery Kingdom when she saw Mavrick, a 14-month-old Atlantic bottlenose dolphin.

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