| Dolphins are one
of the smartest animals living in the ocean. |
| Species |
| There
are about 40 species of dolphins. There are thirty-three ocean
dolphins, five river dolphins, and six different kinds of porpoises.They
have adapted to all of the oceans of the world. |
| Dolphins are not fish; they
are mammals. Dolphins' closest land relatives are pigs, cows,
and deer! Dolphins evolved in the ocean, while hoofed animals
evolved on land. |
| Habitat |
| Dolphins live
in warm water and cold water. It depends on the seasons. Some
dolphins live in really deep water and some dolphins live in
more shallow water. Most dolphins live in salt water. Dolphins
live all over the ocean in different places. |
| Pods |
| Dolphins swim
in pods. Most dolphins swim in large pods. A dolphins pod has
2 to 12 dolphins. |
| Appearance |
| Dolphins come
in different sizes and colors. The most common dolphin colors
are black, white, light gray, and blue gray. All dolphins have
one or more of these colors on their bodies. Dolphins are usually
black above and white underneath. A few dolphin species also
have yellow, tan, and pink. Some dolphins have spots or stripes. |
| A dolphin's face
muscles are below a thick layer of blubber. The jaw bones, blubber,
and skin make a dolphin's face. Even when it is afraid or angry,
a dolphin looks like it is smiling. |
| Dolphins have a beak-like nose
and sharp teeth to eat fish and other foods. |
| Birth of a Dolphin |
| When a female dolphin has a
baby dolphin, the dolphin is born tail first, so it can go right
to the top of the ocean and it can take a breath. A family member
of the dolphin mother will help the mother dolphin have its baby
dolphin. |
| Size |
| Some dolphin species are about
6 feet in length; the males average is 4 to 8 inches (10 to 20
cm ) longer then the females. The largest dolphins are the bottlenose
and the orca. |
| Breathing |
| Dolphins need oxygen to live.
But dolphins are able to send oxygen-rich blood to the brain
and heart. When dolphins dive, they store oxygen in their blood,
muscles, and small blood vessels called retia. Dolphins can also
slow down their heart rate, so they use their oxygen supply slowly.
Even when a dolphin is swimming very slowly, it comes to the
surface for only a very short time. It needs to know the exact
time that its blow hole hits the surface, so that it doesn't
breathe in water and drown. A dolphin has a lot of feeling around
its blow hole. It can feel the differences between water and
air. Dolphins can stay under water for 8 minutes and can dive
to a depth of 500 feet. |
| Sight and sounds |
| There are many different sounds
that dolphins make. They make clicks, squeaks, and screeches
and bubble streams that are often accompanied by a squeak. |
| Dolphins' eyes are different
from ours; they can see under water and in the air, and their
eyes can move different ways. One of their eyes can move up and
one can look to the side. |
| A lady in the Bahamas studies
dolphins and she is trying to figure out how the dolphins communicate.
People say that dolphins are among the smartest animals in the
world. |
| Echolocation |
| To a dolphin, echoes are as
important as fins. The sound is produced in nasal passages. Sound
travels at 1115 ft. per second. Underwater sound travels almost
five times faster!!! The sounds sent out are generally high frequency,
over 200,000 cycles per second. They need echolocation in murky
waters, because they cannot see very well. |
| Activity |
| Dolphins do a lot of active
things, such as dancing, singing, playing or fighting. Dolphins
are very skillful in the water and often play around ships. Dolphins
travel hundreds of miles, hunting the fish that they eat. Deep-sea
dolphins and spotted dolphins will swim into shallow water to
eat. They can keep a speed of 23 miles per hour and leap 3 meters
out of the water. The most widely held reason that dolphins jump
out of the water is so they can see a flock of birds that are
eating, and they can go to the food. When dolphins eat, they
take turns, like they are sharing. |
| Bones |
| Dolphins' bones are softer
than the ones that land animals have. They are filled with fat
and oil. There are only two bones where the hip bone and back
legs used to be. |
| Flippers, Fins and Flukes |
| All dolphins have
two flippers and a tail fin. Most dolphins also have a dorsal
fin on their backs. Another name for the tail fin is fluke. The
dolphin uses its fluke to push itself forward in the water. There
are no bones to hold up a dolphins' tail fin. Tough strands of
tissue called ligaments harden the tail fin and attach it to
the tail vertebrae. |
| Blubber |
Heat is lost in water very
fast. To keep heat from leaving the body, the dolphin has
a thick layer of fat just below its skin. Blubber holds in its
body heat, and keeps out the cold. The dolphin also has special
blood vessels that soak up heat and carry it back to the center
of the body. A dolphins' temperature is normally
96 degrees F to 98 degrees F. A dolphin's body can overheat if
it swims fast over a long period of time. Overheating can cause
a dolphin to get too tired and die. |
| Intelligence |
| Dolphins have large brains.
They are curious and playful. These are signs of intelligence.
Dolphins play with their food, with seaweed, with each other,
with other animals, and with boats. The smartest dolphin is the
bottlenose dolphin. They have been known to understand words.
Rough-Toothed Dolphins are also known to understand commands.
People say that the cleverest dolphin is the orca. |
| Threats |
| The dolphin's worst enemy is
the shark, but humans are slowly turning into the shark's worst
enemy. Thousands of dolphins die every day in fishing nets. |