FAQ about Cetaceans- Dolphins and Whales
Here is a list of Frequently Asked Questions about Cetaceans - Dolphins and Whales I have given to questions posted to me.
Dolphins are air breathing mammals that inhabit all the oceans of the
world. Sleek and aerodynamically formed, they are tight skinned and
feel rubbery to the touch. There are over thirty dolphin species in all,
and they are differentiated from each other not only by size, but also by
shape and markings.
Dolphins are highly
intelligent creatures; in fact, their brain size is larger in proportion
to their body weight than ours is, and considerable evidence exists attesting
to their intelligence. They life is close knit social groups called
"pods", and have a complex communication system, including their own names
or "signature whistles".
Where are dolphins located?
Can dolphins life in fresh water and salt water?
How many different kinds of dolphins are there?
Are dolphins naturally friendly?
What is the dolphins greatest predator?
What is the dolphins life span?
Are dolphins endangered?
How do dolphins sleep?
How fast can a dolphin swim?
What is the distance a dolphin can travel?
How deep can a dolphin dive?
Do dolphins have a sense of smell?
How much do dolphins eat per day?
What do dolphins eat?
How long can dolphins go without being in water?
What is the difference between a dolphin and a porpoise?
What are the sounds a dolphin can produce?
Why do dolphins make so many sounds?
Why do spinner dolphins spin?
How large are spinner dolphins compared to other dolphins?
How can you tell the difference between a male and a female dolphin?
Do dolphins hibernate?
Do dolphins mimic people?
Do dolphins have any form of camouflage?
How often do dolphins give birth?
How long do dolphins stay pregnant?
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 life in fresh water and salt water?
A. Yes, 5 specific species life 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 dolphins 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 lifes 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!
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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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