Dolphins : The Facts of Life

Dolphins : The Facts of Life

Bottle-nosed dolphins move from the Mid-Atlantic in October and November to warmer waters in the south. They return to the Mid-Atlantic in the spring as they follow schools of fish migrating north.

Dolphin Anatomy 101
Dolphins have outstanding vision in and out of the water. In the water, their eyes are protected from the sea water by mucus secreted from glands at the outer corner of the eye. Their ears, small and hard to detect, are located just behind the eyes and have no flaps or lobes. The dolphin's swimming power comes from its caudal fluke, which moves up and down instead of side-to-side like fish. The dorsal fin provides stabilization and may also regulate body heat -- a dolphin's body heat is very close to human body heat at 97.7 degrees F (36.5 degrees C)

What do dolphins eat?
After feeding on mother's milk the first few weeks, calves begin eating fish at 3 to 4 months and are weaned at 12 to 18 months. Dolphins feed on all kinds of fish and crustaceans with adults eating 13 to 14 pounds of fish a day or 20 pounds or more in colder winter waters.

How long do dolphins live?
In captivity, dolphins have lived as long as 40 years. In the wild, though, scientists believe they only live 25 to 30 years.

Dolphin reproduction
Mature female dolphins will give birth every 2 to 3 years and could give birth as many as eight times during their lifetimes. They can give birth at any time of year but most commonly calve in the spring and summer. Females mature sexually at 8 years of younger and dolphins are sexually promiscuous with males competing for females.

How big are dolphins?
Dolphin calves, usually born in the spring, are 2.5- to 3-feet long and 25- to 40-pounds. Feeding on its mother's milk, a calf will double in size in the first few weeks. Adult males are larger than females. The Mid-Atlantic dolphins will reach 7 to 10 feet in length and 300 to 500 pounds by their early teens.

Do dolphins sleep?
Traveling as much as they do, dolphins must rest some time. They don't sleep, though. They merely take cat naps at the ocean's surface for two or three minutes at a time. At night, those naps increase to seven or eight minutes.

How often do dolphins surface?
Because they lack nostrils like most marine mammals, dolphins surface every 15 to 20 seconds to clear their blow holes with a burst of air. They commonly dive 200 meters and can remain underwater for 8 to 10 minutes by slowing their heart beat and controlling their blood flow. Dolphins only breathe voluntarily rather than automatically like humans, so if they're knocked unconscious, they stop breathing.

How fast do dolphins swim?
Dolphins typically cruise at 5 to 7 miles per hour, but they have been clocked at 18 to 22 miles per hour with top speeds of 30 miles per hour.

How do dolphins travel?
Dolphins travel in pods of up to 15. A pod typically consists of several adult females, calves and adult males. Pods may travel together in herds of several hundred individuals. Dominance or aggression, in the form of a showing of teeth, tail smacking, jaw snapping or head butting, establishes the hierarchy in the pod.

Dolphins : The Facts of Life

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