Facts and informations about Dolphins
You find here a website, filled with facts and informations about cetaceans- dolphins and people associated with dolphins.
- Physiology
- Reproduction
- Communication
- Social Structure
- Intelligence
- Range
- Dolphins and Humans
The majority of small tooth whales are called dolphins. They are mammals
of the order Cetacea and the families Plantanistidae and Delphinidae and
include about 50 species. All have a beak like snout and sharp, conical
teeth. The term porpoise is sometimes applied to many of the same
species, but porpoises, are members of the family Phocaenidae and have
a blunt snout and spade or chisel shaped teeth. The dolphin
mammals, is neither a dolphin nor a porpoise. It is a sport mammal
related to the mackerels.
Most dolphin species are about 6 ft in length, the males averaging 4 to
8 in longer than females. The largest is the bottle-nose dolphin which can
reach over 9ft in length and weigh 440 lbs! The smallest species is the buffeo,
found in the Amazon River. The buffeo rarely grows over 3.9 ft in length and
66 lbs in weight, really smalled compared to the bottle_nose.
Dolphins feed on live food and are predators, except when trained otherwise
in captivity. The primary food is fish, mostly things like herring, mackerel,
and sardines. Some species seem to prefer squid, occasionally, shrimp and
other crustacean are consumed, and even mollusk shells have been found in
their stomach contents. Food consumption is estimated at about 66 lb a day for
an individual about 8.2 ft in length and 220 lb in weight.
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 Head (Melon)
The rounded forehead uses an extremely sensitive
echolocation system with the melon acting as an acoustical lens that concentrates
sound waves that are then projected through the water to locate
shoals of fish.
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 Teeth
The teeth can be used to distinguish dolphins
from porpoises. Dolphin's teeth are used for grabbing hold of food, and
are not used to chew the food.
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 Fins and Flukes
The dorsal fin is made of cartiledge. It is highly
curved and positioned towards the middle of the back of the dolphin,
its unique shape and pattern notches can be used in identifying
individual dolphins.
The flukes are broad and curved, and it pointed
flippers of a moderate length.
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 Eyes
Dolphin's have special glands that protect their
sensitive eyes from the salt water of the ocean. The eye lens itself
can expand and contract to allow them to focus their vision both
above and below the water's surface.
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 Blowhole
This remains closed whilst the dolphin is under
the water, but upon reaching the surface it opens to allow the dolphin
to breath. Whilst still asleep dolphins will rise to the surface
of the sea and draw in oxygen before resubmerging a few feet beneath
the water.
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The general form of dolphins is a classic example of streamlining. The
body is sleek and smooth and the hairless skin is rubbery to the touch. Most
species have jaws that protrude into a beak like snout. Above the upper jaw
is a large mass of fat and oil-containing tissue forming the so-called
"melon" that looks much like a bulging forehead.
The anterior appendages contain the skeletal remnants of five digits
that form the flippers, which the animal uses primarily as stabilizers,
although occasionally in an oar like fashion. The hind appendages are
virtually absent and consist of a pair of small pelvic bones, deeply embedded
in the connective tissue at the base of the tail. The dorsal fin is
formed from subcutaneous dermal tissue and is not movable by muscle action.
The caudal, or tail, fin is also primarily dermal in origin, rather than
skeletal, and consists of a pair of horizontally extending flukes. The locomotion
of dolphins is typical of the whale. The main thrust comes
from vertical oscillations of the tail and flukes, and most species tested
are capable of sustained swimming speeds of up to 18.6 mph and they jump
at this high speeds travelling 30 ft or more. Their normal "cruising
speed" is about 23 to 25 mph, and if they are bow riding, they have been
known to get up to 30mph. Bow riding is when the dolphin rides teh
bow of a wave produced by a ship.
Because dolphins are mammals, they must breathe air and maintain a high
body temperature. The internal temperature, between 97.9 deg to 99 deg
F, is acheived by a thick layer of blubber under the skin. Air is
breathed through blowhole, situated almost directly on top of the head.
The dolphin normally comes to the surface to breathe about every two minutes,
and each breath consists of a short, almost explosive exhalation,
followed by a slightly longer inhalation. Dolphins can hold their
breath for up to several minutes and are capable of rapid and deep dives
of more then 1,000 ft. The respiratory system is specially modified to avoid
the BENDS.
Dolphins once were hunted commercially, especially for the small quantity
of valuable oil extracted from parts of the head and used to lubricated delicate
watch mechanisms. Cheaper oils have now been found from other sources, and dolphins
are no longer hunted for this reason. Many dolphins, however, become accidentally
trapped and drowned in tuna nets. Between the years 1959 and 1972 an
estimated 4.8 million dolphins died this way. Beacuse of the pressure from
animal rights activists and United States consumers, both domestic and international
tuna canners have refused to accept shipments from fishing fleets that do not protect
dolphins. The Marine Mammal Protection Act of 1972, amended in 1988 and 1992, was
passed to prevent exploitation of dolphins and related aquatic animals.
The National Marine Fisheries service
is the principal regulatory agency.
Captive dolphins, mostly the bottle-nose dolphin, has provided us with
the reproductive behavior studies. Mating normally occurs during the spring
months, like with most animals, with the male-female pair exhibiting courtship
for some time prior to the actual mating. A female dolphin has to carry her baby
(calf) for 11-12 months. The calf is delivered normally tail first,
and the newborn is capable of swimming and breathing within the first minutes.
Some mothers have been observed raising the calf to the surface, as if
to help it, but dolphins apparently play in this fashion with a variety
of objects, living or not. This kind of play may have helped the
stories heard round the world of how dolphins have helped humans when they
have been lost at sea, helping them get to the surface and to stay there.
After birth, the calf will follow its mother closely, and suckling takes place
frequently, with the mother tolling slightly and the calf nuzzling the mammary area.
The dolphin's two mammary glands open into a pair of sacs on either side of the anal
opening, and the calf's beak fits into the openings on the sacs. The nipple is
grasped between the upper jaw and the tongue, and muscular contractions by the
mother literally squirt mil into the calf's mouth. Nursing may continue for as
long as 12 to 18 months after birth, although weaning is probably slowed or
inhibited in captive animals.
Dolphins are extremely and almost constantly vocal. They are capable of
two kinds of sounds. A specialized mechanism in the nasal passages just
below the blow-hole enables them to emit short, pulse-type sounds. These
sounds, called clicks, can be produced in such rapid succession as to sound
like a buzz or even a duck like quack. The clicks are used as a form of
sonar, in which echoes of sounds from surrounding objects enable the animals
to detect obstacles, other dolphins, fish, and even tiny bits of matter
in the water. The military uses dolphins and this ability to help
them find water minds. This ability is termed ECHOLOCATION.
Some Scientists have speculated that dolphins also use the sounds to deliver
an acoustic shock for stunning of killing small prey.
Deeper in the respiratory system--presumably in the larynx--dolphins
produce another type of sound: a high pitched whistle of squeal, which is
capable of rapid pitch changes. The whistles differ from the clicks in being
essentially single tones. Apparently the dolphin used the whistles to communicate
a particular emotional state and thus influence the behavior of other dolphins.
Typically, the squeals denote alarm or sexual excitement. It has been suggested by
several noted scientists that dolphins may be able to create acoustical holographic
images from the interlacing of their sonic output. It is well known that
dolphins can see inside the bodies of their fellow dolphins, and other animals
in the water. This is because dolphin sonar evolved to pass through water
and does not reflect until it hits something like bone or air sacs. Since animal
bodies are more than 50% water, their sonar enables them to literally "see"
inside other animals. It is possible that dolphins can read the emotion of other
dolphins and "see" through the bodies of other animals due to their
"x-ray" vision.
Dolphins have a well-developed tactile sense. They are often in contact with
traveling companions. Body contact is an important component in communication,
and is accomplished through rubbing, petting, and hitting among other forms of
touch. Some examples include the contact between a mother/calf pair, pectoral
fin to pectoral fin rubbing, swimming while remaining in contact with another,
and rubbing bodies. Mutual pectoral fin rubs may be exchanged by two dolphins
that have just come together. These may be a sort of greeting, similar to a
handshake or hug between two people. Or, sometimes dolphins swim a distance and
one individual rests its pectoral fin along the side of a second individual.
This behavior, called contact position, may be a signal to others that these
two are close friends. It could also mean that the first dolphin wants a favor,
so to speak, from the second.
Body contact is often modified by the posture of the dolphins involved.
Direct or perpendicular approaches are usually observed during aggressive
exchanges, while approaches from behind or at oblique angles seem to be less
threatening. We should remember this when we swim among dolphins! Visual cues,
such as body coloration or posture, are also important avenues for communication
among dolphins. All these signals combine in various ways to communicate vital
information such as age, gender, sexual responsiveness, identification and activity.
Dolphins are social animals with groups ranging in size from two to 15 animals, and
often containing more. Many studied dolphin communities seem to be "matrilineal", consisting
of females and their accumulated offspring, or sisters and other females. Calves within
these groups will often develop stable relationships with each other over a period of years.
Subadult males will usually leave these groups and form "bachelor" groups that often
remain together. Sexually mature males may form partnerships or coalitions with other males
and seem to move throughout the female groups. There is no evidence for strong social bonds
between male and female pairs. Play is an integral part of social relations for dolphins.
They are frequently seen riding the bow wave or stern wake of boats and "surfing" on waves.
Both juvenile and adult dolphins often chase each other and toss things to one another, such
as seaweed. Jumping from the water's surface and breaching can also indicate excitement.
Play is often an extremely important mechanism for learning and for practicing skills that
assist a dolphin in survival.
Because dolphins are highly social and vocalize among themselves with a wide range of
sounds, it has been conjectured that they might possess and almost human like intelligence.
In the 1950s and '60s the American neurologist John
Lilly conducted well publicized experiments based on this concept,
in which he attempted to communicate with dolphins in their own "language,"
but other scientists have rejected his work as poorly documented and lacking
scientific validity.
Because of the ability of dolphins to learn and perform complex tasks in
captivity, their continuous communications with one another, and their ability,
through training, to approximate the sounds of a few human words, some investigators
have suggested that the animals might be capable of learning a true language
and communicating with humans.
Most researchers agree
that dolphins exhibit a level of intelligence greater then that of dogs
and even comparable to that of some primates--but not human beings.
Research into dolphin intelligence continues at centers such as Hawaii's
Kewalo Basin Marine Mammal Laboratory (The Dolphin Institute).
Dolphins can be found in virtually all the seas and oceans of the world. Some
species are sharply restricted, but many, like the common dolphin, Delphinus
delphis, or the bottle nose dolphin, are found worldwide. Several species are
found in fresh water, notably the Ganges River dolphin, Platanista gangetica;
the rivers of South America are the home of the long-snouted dolphin, Inia
geoffrensis, and the small, graceful Sotalia fluviatilis, occasionally
seen as far as 1,553 miles (2,500 km) up the Amazon River.
Dolphins are quite abundant in some areas of the world. Off the
coast of Japan, for example, populations of the white-sided
dolphin, are estimated at 30,000 to 50,000 individuals. In many
species, schools of up to 1,000 travel together, while some species, such
as the bottle-nose dolphin, tend to be found in smaller groups of less
than 100, or even just a small family group. Solitary individuals are,
however, rare.
Dolphins adapt well to human companionship and are readily trained.
Bottle-nose dolphins have become well known performers in may aquariums;
they are capable of spectacular tricks and may mimic the sounds of a few
human words. Dolphins are also being studied by scientists and the military
for possible use in undersea operations, but the U.S. Navy has dropped
plans to use them to guard nuclear submarines. Dolphins at one time were
hunted commercially. Some flesh and blubber were used, but the main product
obtained was a fine quality oil that was extracted from the lower jaw of the
dolphin. Although the oil remains highly prized as a lubricant for delicate
watch mechanisms, similar and cheaper products are available from other
sources, and commercial dolphin fishing is virtually nonexistent. Many dolphins
have been destroyed inadvertently by commercial tuna fishers using purse nets.
A tuna boycott pushed U. S. tuna canners to agree in 1990 to buy tuna only
from boats that fish in areas where the dolphins and tuna swim separately.
11 tips for contact with dolphins:
1.
Don't approach a dolphin on any case if you are ill. Dolphins catch from people easily
and have a relatively weak immune system. Already a harmless cold can get dangerous them!
For the same reason you should wash your hands before you touch the dolphin.
2.
Put all sharp-egded and metallic objects like jewelry and clocks down before because
the skin of dolphins is very sensitive and they hurt themselves at it easily. The same
also applies to long fingernails. Also avoid any form of Chremes and oils, such as suntan
oils and Sonnenchremes or cooked make-up. The chemical substances contained in it and
connections are pure poison for Delphine!
3.
Never touch the dolphin at the forehead over the muzzle because they don't like this.
Melon and blowhole are very delicate organs. Be never rough with the dolphin but grasp
it gently.
4.
Dolphins may eat an exclusively only fresh raw fish or squid, of other things they get ill.
So try never to feed them with a little different.
5.
Dolphins are usually very peaceful and kind but, if they are in or afraid a really bad mood,
one should handle them just as carefully as with other big animals. It is the problem that
her body language isn't trusted to us people and that we don't such as with a growling dog
immediately recognize what the dolphin has. If a dolphin gives croaking noises, jerks with
the head or beats hard with the tail fin on the water without a coach having ordered this
to it, then it is annoyed about something. In this case leaves it better and comes back some
other time.
6.
If you are in the water with a dolphin, then chases or doesn't pursue him but lets him come
from liberal wills to you. Make him to become acquainted with curious about it, you instead.
If you stay in movement, dive in the direction of the seabed or in the water of a little
herumturnst, then one often gets spontaneously from them to you because you work as an
interesting playmate. Fun and game dear to Delphine!
7.
Swim smoothly and supply and hold the arms at the body. Ideal would be a swimming technology
at which you imitate the swimming movements of the dolphins. Don't try to pack the dolphin
unless its coach tells you provided that one is there that it is all right to touch it. The
dolphin vorbeistreift completely approaches at you, OK, thus perhaps it is then it signaled
that it would like to be touched only if.
8.
Although it seldom happens that a dolphin has an aggressive behavior.
He he wanted to ram you and only only just stops in front of you or if you have the feeling if,
however, he is pretending when you one at all puts pressure on way, the water then immediately
leaves that into. Although dolphins are very kind animals though know how also she to claim
herself in a conflict situation. Cases were already reported that dolphins ram a penetrating
approaching shark with ihrern muzzles to death.
9.
If somebody tries to annoy the dolphins or handles really roughly them, then prevent it from
it presently.
10.
There isn't any reason to be afraid in front of a dolphin! You experience something excellent
and uniquely beautiful at a meeting with a dolphin. You will to meet and get to know notice
fast how much fun and joy makes yourself, a dolphin. From my own experience I can report that
one doesn't forget an in such a way beautiful experience for his life.
11.
As seldom as possible eat tunafish. Tunafishes and dolphins often swim together and one suspects
that they simply get on well and cooperate at the hunting. Unfortunately, fishermen make use
of it and dolphin schools catch to approach the tunafishes swimming under them. At these actions
hundreds of thousands dolphins die every year although it is tried already meanwhile to develop
better catch methods. Unfortunately, one cannot rely on the imprint "Dolphin safe" at tunafish
doses either. It is the best, you avoid completely eating this fish.
Here are some other dolphin facts that you may find interesting...
Dolphins tend to live for about twenty years, but some have been known to live for about forty years.
When dolphins sleep, they sleep in a semi-alert state by resting one side of their brain at a time
If need be, dolphins can hold their breath for 5-8 minutes at a time
Dolphins can dive as deep as 200m (that's 650ft)
A dolphin sheds its outer layer of skin every two hours
Dolphins will help sick or injured dolphins as much as they can
Dolphins work as a team if danger is near by
Every dolphin has its own signature whistle to distinguish itself from its companions
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Actual programs for adopt Dolphin or Whale
Would you like to adopt a whale or dolphin? Following are one or more dolphin and whale
adoption programs. Most provide a certificate, photo, chart, and quarterly newsletter.
Check out the following web sites and contact the organizations if there is one for more
information about the programs.
»The Whale and Dolphin Adoption Project«
»Delivery UK wide; The Adopt a Dolphin pack«
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