Bottlenose Dolphin

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Bottlenose Dolphins (Tursiops truncatus)are a common sight along the Gulf Coast. These images are from Port Aransas, Texas. The photo below was used on the cover of the October 1, 2009 edition of the Port Aransas “South Jetty” weekly newspaper:

Copyright 2009, David E. Shormann

Adult dolphins reach lengths up to 12 feet (4 meters), and males are normally larger than females. Dolphins typically live 20-30 years, but have been known to live up to 50 years. Bottlenose are dark gray on top, fading to white or pink underneath. An average sized (550 lb) dolphin will eat 20-50 pounds of fish each day! Dolphins find fish to eat using sight, but they can also hunt at night and in murky water by using echolocation. When a dolphin uses echolocation, it is basically creating a picture of its environment using sound. Although dolphins produce a range of sounds, the most useful sounds for echolocation appear to be clicks of short duration released in single pulses or trains of pulses. These clicks may be repeated up to 800 times per second. Dolphins have no vocal chords, so the sounds they produce are believed to be created by forcing air through their nasal passages and nasal sacs. The bulbous head of the bottlenose is filled with fatty tissue, and is believed to act like a lens, concentrating the clicks into a “beam” of sound. Their sounds can travel over half a mile, and they can even use their sounds to stun prey. So not to confuse outgoing sounds with returning sounds, outside sounds enter through the lower jaw and travel through the skull by bone conduction. Fat and oil bodies within the lower jaw vibrate, adn the sound is channeled directly to the middle ear. The hearing center in a dolphin’s brain is well-developed, probably so that it can analyze and interpret returning sound messages. For comparison, a human ear can hear in the range of 16 to 20,000 vibrations per second. A bottlenose dolphin responds to frequencies above 150,000 vibrations per second!

A dolphin’s vision is not as good as human’s, and it is believed they have no sense of smell, but they can taste. Dolphins reproduce sexually, and like all mammals, give birth to a baby that feeds on its mother’s milk. Dolphins have an 11-month gestation period, with babies being born mainly in the spring. Dolphins swim in groups or pods of related dolphins, and work together to trap fish, squid, and other food items.

Sometimes dolphins like to jump in the bow wake of large ships, like these three dolphins are doing:

Copyright 2009, David E. Shormann

Sometimes they jump for no apparent reason!

Copyright 2009, David E. Shormann

Here is a video of dolphins jumping in the bow wake of a tanker:

While the dolphins in these photos and video are jumping, they also like to dive, and have been recorded to dive to depths of about 1,000 feet (300 m)! They have a horizontally-positioned caudal fin, which they move up and down for propulsion. This is different than in fishes, which move their vertically-positioned tails from side to side. A rigid dorsal fin and a pair of flippers are used for stability and turning. Dolphin’s skin is smooth and slippery, allowing them to attain speeds up to 25 miles per hour (16 kph).

Dolphins rank second in intelligence only to us humans, but even as smart as they are, their creative abilities are less than toddler’s. Only humans, who were created in God’s image, were designed to be anywhwere near as creative as Him. You won’t see dolphins building skyscrapers, composing music, or drawing self-portraits! Dolphins are capable of learning many things though, and are easy to train in a way that shows off their incredible strength and agility, as shown in this video from the Texas State Aquarium:

The Marine Mammal Protection Act forbids harassing, feeding, or interfering with a dolphin’s normal activities. Sometimes, their “normal” activities include being extremely curious and approaching humans within just a few feet.

Copyright 2009, David E. Shormann

If you visit the Gulf Coast, you may not be greeted by a dolphin in such a personal way, but if you are, turn the boat motor off, keep out of the water (dolphins may bite), and enjoy the show!

Click on this link to print a COLORING PAGE:       bottlenose dolphin

Explore posts in the same categories: Marine animals, Wildlife Facts and Photos

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