
Dolphins are highly
intelligent creatures, and considerable evidence exists attesting
to their intelligence. They live is close knit social groups called
"pods", and have a complex communication system, including their own names
or "signature whistles".
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Q. Where are
dolphins located?
A. Dolphins
have colonized all oceans and seas of the planet, from polar to tropical
regions. Presence or non presence of dolphins is a good indication
of the state of the seas in many parts of the world.
Q. Can dolphins
live in fresh water and salt water?
A. Yes, 5 specific
species live in fresh water, they are usually named after the river they
swim in such as the Amazon, the Yangzi Jiang, or the Ganges.
Q. How many
different kinds of dolphins are there?
A. There are
32 species of oceanic dolphins (Delphinidae family) and six porpoise species
(Phocoenidae family). There are five river dolphin species found
in five different rivers.
Q. Are dolphins
naturally friendly?
A. Dolphin species
vary in their degree of curiosity and interaction with humans. Individual
dolphins vary to the same degree. Some species are very shy, others
will approach humans with great curiosity. If dolphins have spent
time in captivity, they can become very used to people touching them, riding
along side of them, etc., but they also can become mildly aggressive; nipping,
pushing, etc.
We all heard of the
famous stories about dolphin rescues where a human is pushed to the safety
of the shore by dolphins. Bottle-nose dolphins seem to enjoy pushing
items. (Of course we wouldn't hear about the people being pushed
out to sea!)
Q. What is the
dolphins greatest predator?
A. MAN!
Man is the dolphins greatest predator, more then 100,000 dolphins die each
year because of man, either in nets or for gastronomy.
The second predator is the shark, the worst areas for these "too close" encounters are South Africa and Australia.
Finally the third is the.........dolphins. Orcas have the habit or eating fish, seals, infant whales and small dolphins.
Q. What is the
dolphins life span?
A. The average
life expectancy for the bottle-nose dolphins is about 25 years. the
maximum age (which only a few will reach) is more than 40 years.
Q. Are dolphin
endangered?
A. The river
dolphins are the only dolphins that are endangered or vulnerable right
now.
Q. How do dolphins
sleep?
A. Dolphins
sleep only with one half of their brain at a time. Remember dolphins
are conscious breathers. Should they sleep and go unconscious as
we do they would simply suffocate or drown. Sleeping dolphins can
be seen as resting, floating at the surface, with one eye open. After
a time, they will close the one eye and open the other one. They
alternate like this throughout their entire nap.
Q. How fast
can a dolphin swim?
A. Dolphins
can swim up to 40 km/hr, due to special structures in the skin that reduce
turbulence. They spend the least amount of energy when swimming at
speeds of about 8 km/hr.
Q. What is the
distance a dolphin can travel?
A. The distance
a dolphin travels depends very much on its food supply. The optimum
swimming speed is about 8 km/hr. Dolphins sleep about 8 hours a day
which would leave 16 hours for travel. This would mean they can travel
up to 128 km per day. How much they actually do travel is unknown.
Q. How deep
can a dolphin dive?
A. The dolphin
is capable of diving for up to 20 minutes at 300 meters, this is to be
considered as maxima for a bottle-nose dolphin although in some experiments
they have dived to about 500 meters. Usually, bottle-nose dolphins
will not dive very deep.
Q. Do dolphins
have a sense of smell?
A. Dolphins
can taste, but have no sense of smell.
Q. How much
do dolphins eat per day?
A. Bottle-nose
dolphins consume approximately 8-15 kgs (15-33 lbs.) per day and Orcas
approximately 45 kgs (100 lbs.) per day.
Q. What do dolphins
eat?
A. Dolphins
and porpoises are carnivores - most eat fish and/or squid. Different
habitats mean different diets; each type of dolphin and porpoise specializes
in catching prey that lives in their specific ecosystem.
Q. How long
can dolphins go without being in water?
A. Dolphins
and whales out of water have two problems: heat and their own weight.
Large animals have low surface to volume ratios, so it is hard for them
to cool themselves. Also, whales are well insulated (blubber), which
is good if they're in the water, but not if they're beached. It's
like having a winter coat on in 70 degree weather, you'd overheat very
quickly. A whale's body isn't designed to support its own weight,
it relies on water for support. The larger whales will die from their
own weight if they're beached long enough.
Q. What is the
difference between a dolphin and a porpoise?
A. There are
slight physical differences between dolphins and porpoises:
*
Porpoise teeth are shaped like spades and each tooth has a long, sharp
upper edge.
*
Dolphin teeth are shaped like cones and are pointed.
*
Porpoises tend to be smaller than dolphins and usually do not have pronounced
beaks.
*
Whales, dolphins and porpoises are in the same scientific group Cetacea.
*
"Whale" is a common name used to describe a large cetacea. It relates
to relative size, much like the distinction between "boat" and "ship".
*
Killer whales, melon headed whales, pilot whales, and false killer whales
are all part of the dolphin family, but are called whales because of their
size.
Q. What are
the sounds a dolphin can produce?
A. All dolphins
and whales can produce complex sounds, both for communication among them
and for navigation under water. The common dolphin can hear sounds upwards
of 150 KHz but generally produce sounds ranging from 1.5 to 11.0 KHZ.
Patterns of sounds can be observed, mostly clicking, moans, whistles, trills,
and squeaks. Males can whistle to get the attention of females or
to warn the group of imminent danger (so does man, we are all mammals).
Q. Why do dolphins
make so many sounds?
A. Whistle like
sounds help dolphins keep in contact and communicate with each other as
they travel and feed. Dolphins "echolocate" to find their food or
to scan their surroundings. They direct "clicks" into the water and
the clicks rebound off solid objects (fish, logs, boats) and echo
back to the dolphins. Dolphins listen for the strength of the rebounding
clicks to identify what the object is and its distance from them.
All of these clicks and whistles are created in the dolphin's nasal passages
just below the blowhole.
Q. Why do spinner
dolphins spin?
A. There is probably
more than one reason for why spinner dolphins spin. The one that has been
documented the most has to do with remoras, a group of fishes that has
one of the fins on their back modified into a suction cup. The suction
cup allows the remora to attach to a shark, marlin, whale or dolphin to
get a free ride. The problem for the marine mammals is the way the fish
makes sure that the suction cup does not slide around on its host,
by sinking thousands of little needle-like bones into the skin of the host.
This does not cause much of a problem to a shark or a marlin, but
to a dolphin, with sensitive skin, it may be a major irritant.
If looking at photographs of spinning dolphins, one will find a remora attached to the spinner in about 70% of the photos. This is especially significant, when you consider that you will only be able to see 50% of the spinner dolphin's body in the photo.
Q. How large are spinner
dolphins compared to other dolphins?
A. Spinner dolphins
are one of the smallest species of dolphins. They are only 1.5-2 meters
long, an they weigh around 75-95 kilograms. For a comparison, bottlenose
dolphins (Flipper was a bottlenose dolphin) can reach lengths of
almost 4 meters and weigh up to 600 kilograms!
Q. How can you tell
the difference between a male and a female dolphin?
A. To find this out
you have to look underneath the dolphin at it's belly. If you see
a long slit with 2 smaller slits, that's a female:
_
Head _______
tail
_
The smaller slits are the openings for the mammary glands.
For a male, it's more like this:
Head ____ _ tail
(No slits to the sides.)
Q. Do dolphins hibernate?
A. No. In fact,
they never fully sleep. When people breath, they do so involuntarily;
as they sleep, they continue to breath. Dolphins, on the other hand,
must swim to the surface, and then breath voluntarily. As a result,
they don't sleep like we do. It is believed that only half of their
brains sleep at a time. While one half of their brains is asleep,
the other half is monitoring their swimming to the surface to take a breath.
Q. Do dolphins mimic
people?
A. In general, no.
Some dolphins in captivity have learned to mimic people, where they get
'rewards' for doing so. But those in the wild do not - there
is no reason for them to do so.
Q. Do dolphins have
any form of camouflage?
A. Yes, seen
from above they blend in with the water, and if you're a killer whale looking
up, their bellies blend in with the sky. It's called counter
shading.
Q. How often
do dolphins give birth?
A. Dolphins like bottlenose
dolphins give birth about once every 2-4 years. If the calf is healthy,
it will nurse for 1-2 years...weaning takes place then but it takes awhile.
Q. How long
do dolphins stay pregnant?
A. Dolphins are pregnant
for a whole year!!
Q. How intelligent are dolphins?
A. 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, BTW). Also they can learn to understand complicated
language-like commands (which is also true of the great apes).
Q. How high can a dolphin jump?
A. Dolphins can jump
as high as 5 m (16 ft.) from the surface of the water and landing on their
backs or sides.
Q. What is a Male/Female/Baby dolphin called?
A. A male dolphin
is a bull, a female dolphin is a cow and a baby dolphin in a calf.
Q. What do dolphins drink?
A. Dolphins’
main prey (fish and squid), contains large amounts of water and so dolphins
obtain water from their food. Fish, such as herring and mackerel can be
made up of as much as 80% moisture, whilst moisture levels in squid are
even higher. In addition, dolphins don't actually need to take in very
much fluid because, unlike us, their skin is impermeable and they don't
lose water by sweating.
Q. Do dolphins have hair?
A. Dolphins
are born with a small amount of hair on their beak (nose), but in when
they become adults, only the hair follicles remain.



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Last updated 04/06/06 |