Dolphins
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There are 33 different species of Dolphin
around the world, many living in the waters around Australia.
The most common species of Dolphin is the Bottlenose Dolphin,
which live in varying climates. Dolphins are warm-blooded
mammals, which breathe air, and due to their social nature
often live in pods of about 15 dolphins. |
Dolphins have extremely sensitive skin, which
has a rubbery feel. Their circulatory system is very good for
preserving heat, with blood vessels in their dorsal fin, flippers
and tail re-warming cool blood to spread around the body. Dolphins
also have fantastic eyesight, enabling them to see both in and
out of the water. However, they can only see infront of them and
below them, and so have to swim upside down sometimes to catch
fish.
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The average size of Bottlenose Dolphins
is between 2 - 4 metres long, weighing between 90 - 650
kilograms. However, they vary in looks according to where
they live and spend their lives. Dolphins eat plenty of
food daily, totaling about 5% of their body weight. They
catch fish, octopus and squid with their sharp teeth, although
swallow the food whole and digest it in their stomachs.
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Dolphins can stay under the water for about 15
minutes, and can swim to depths of over 100 metres due to their
collapsible ribs, which vary according to the water pressure.
They can also jump about 6 metres out of the water, and love surfing
on waves.
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Dolphins have a wide range of ways of
communicating, much like humans. Ways in which they communicate
with each other include body posture, bubble blowing, chemical
releases, language, sound, touch, and splashing on the waters
surface.
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Dolphins can be recognised by their unique
'Signature Whistle', which is an extremely high-pitched
sound. This sound comes from their blowhole on the top of
their heads. They also send out clicking sounds, which bounce
back to their forehead to identify the size and distance
of objects around them.
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Due to the constant danger of predators Dolphins
don't ever sleep, they merely nap for about 30 minutes with half
their brain alert.
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Dolphins become sexually active at around
the age of 10 and generally live up until around 30 years
old. Female Dolphins carry young for 12 months and give
birth to live young. During the birth an 'aunty' dolphin
will help, although many calves are soon taken by predators.
When this happens the mothers mourn for their young, continually
pushing them to the surface to breathe.
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During the first two years of birth the calves
will feed off of milk from the mother. Dolphins give birth every
2 - 4 years and once the calf is about 3 years old, it is ready
to go off on its own.
Dolphins are in great threat from a wide variety
of objects and actions within the water. Dolphins and other marine
life often get caught up in fishing lines, and have difficulty
with Stainless Steel hooks caught in their mouths. Rubbish and
other waste products can also be swallowed by Dolphins, causing
pain. They also often have difficulty getting out of the way of
speed boats and jet skis.
Dolphin Language
- Blowhole - Hole on the top of their head, which they use to
breathe
- Blubber - Insulating layer if fat under the skin
- Breaching - Leaping out of the water, and crashing down onto
it
- Cetacean - Scientific name of Dolphins, Porpoises and Whales
- Delphinidae - Family name for the entire dolphin group of
Cataceans
- Dorsal Fin - Fin in the middle of the back
- Echolocation - Sending out sounds to find out what is around
them
- Exhale - Breathing out of its blowhole
- Flukes - Tail flukes help the Dolphin move through the water
- Ghost Nets - Loose fishing nets floating around the seas
- Home Range - The home base for a Dolphin
- In-Shore (Tursiops aduncus) - Dolphins that live within about
10km of the coastline
- Inverted Hunting - Swimming upside down to catch a fish on
the surface of the water
- Logging - Relaxing on the surface of the water
- Melon - Fatty tissue on the Dolphins forehead that is used
for their Echolocation system
- Mysticetes - Whales with plates instead of teeth
- Odontocetes - Dolphins, Purpoises and Whales who have teeth
and not plates
- Pectoral Fins - Side fins, used to steer
- Pod - A group of Dolphins. Rake Marks - Teeth marks from other
Dolphins
- Resident Dolphins - Dolphins that live in one area
- Rostrum - Part of the mouth above the lower jaw
- Signature Whistle - A unique high pitched whistle sound made
by Dolphins
- Spy Hopping - Looking around with their head out of the water
- Stalked Barnacles - Barnacles which attach themselves to mammals
- Tail Slap - Slapping the tail against the surface of the water
to show frustration
- Transient Dolphins - Dolphins that constantly move from place
to place
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