Interesting Facts About Dolphins
Dolphins are fascinating, intelligent and highly social animals. They have a reputation for being helpful and even saving human lives, although they can also be dangerous.
Here are some things about dolphins you may or may not know.
They See In Sound
Although dolphins have perfectly good eyes, sight is not their primary sense...sound is. The bulge in a dolphin's forehead, called the 'melon', contains a set of natural sonar gear as good as anything designed by humans.
This allows dolphins to navigate deep underwater where light may be very low or even non-existent. They use 'active' sonar, meaning they produce high-pitched sounds that bounce off objects. These sounds are ultrasonic - humans can't hear them, although some dolphins have been trained to produce the clicks at a lower volume to 'show them off'. A dolphin's sonar is so good that they can tell the difference between a pellet from a BB gun and a corn kernel at fifty feet.
One thing dolphins have a problem seeing with their sonar is fishing nets. Because of this, most fishermen now place plastic shells or balls on their nets. The dolphins can see these and then they don't swim into the nets while chasing fish.
They Have Names
Observation of dolphin pods has indicated that dolphins make sounds associated with individuals and, just like humans, have their own names.
Dolphins will produce their name-sounds when meeting strangers (although not all the time...maybe some of them are shy) and use them to identify members of the pod. They can even recognize their own name when its spoken by a total stranger.
No other animal has been found to use names, although domestic animals do learn to recognize the names we give them, and there is now some evidence some species of parrot may name their hatchlings.
A New Meaning To 'Half Asleep'
Dolphins need to keep swimming all the time, or they will drown. So, how do they sleep?
The answer is...half at a time. Dolphins sleep by shutting down one hemisphere of the brain for a while, and then the other. The other hemisphere remains conscious and controls their swimming. What dolphins might experience while 'half asleep', of course, is unknown. What is known is that while asleep they tend to show one of three patterns: Swimming slowly and surfacing occasionally, resting at the surface with their blowhole exposed, or sleeping on the bottom in shallow water, surfacing when they need to breathe.
Some dolphin populations will swim into coastal lagoons or shallow bays every night and sleep in the same place, perhaps so that they don't drift so far while sleeping. Like us, they sleep about eight hours a day...four each side.
Water, Water, Everywhere...
So, if drinking salt water makes you thirstier than you started, how do dolphins manage?
The answer is that dolphin water metabolism is the same as a desert animal. They do not drink water directly, but absorb water from their food and store water in fat (just as a camel stores water in its fatty hump). They have desert animal kidneys, designed to retain as much water as possible.
Hey, baby...tail first
In almost all mammals the ideal birth is when the baby comes out head first, including humans. Breech births in humans cause all kinds of complications and they're just as bad in farm animals.
Dolphin babies, however, always emerge tail first. Why? So their breathing reflex is not activated until they are all the way out and they don't end up with a blowhole full of water.
When a dolphin calf emerges, a midwife helps it to the surface as quickly as possible to get its first breath. (In orcas, which despite being otherwise known as 'killer whales' are a kind of dolphin, not whale, this task is performed by a male - daddy, perhaps?).
This makes dolphins one of only two non-human animals to routinely require assistance in giving birth, the other being elephants.
You ain't in this club
Dolphins form cliques - and pass on skills and habits only to those they like. For example, a group of dolphins that use a sponge to protect their nose form an exclusive 'club'...just as human surfers tend to hang out together.
And, just like in high school, the girls are far worse about it than the boys.