Spinner Dolphins Life Span Behavior and Degradation Due to Fishing
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Spinner Dolphins Life Span Behavior and Degradation Due to Fishing

The spinner dolphin (Stenella longirostris) is a very unique species of dolphin. Spinner dolphins are characterized by their uncanny ability to spin when they “breach”, or jump out of the water.

There are several species of dolphins swimming in Earth’s waters. The spinner dolphin (Stenella longirostris) is a very unique species. Spinner dolphins are characterized by their uncanny ability to spin when they “breach”, or jump out of the water.

Spinning

All dolphins breach. Breaching is the act of leaping out of the water and diving back in. When spinner dolphins breach they twist or spin their bodies around as if on an axis as they are airborne. They can breach nearly ten feet into the air. Spinner dolphins can spin their bodies around up to seven times in the air before diving back into the water. It is not known why spinner dolphins spin when they breach.

Physical Characteristics

A spinner’s size ranges from five and half feet to seven feet long. The males are slightly larger than the females. Dwarf spinners which are only found in the waters of Thailand are only five feet long. They are usually light and dark grey with white bellies. They have long slender snouts which look like long beaks.

Life Span

Spinners live from 30 to 40 years. Males reach sexual maturity at ten to twelve years. Females are mature at five to seven years. Females have an eleven month gestation, or pregnancy, period and typically give birth every two years.

Location

Spinner dolphins live in tropical waters. They are found mostly along the coasts of Hawaii, Costa Rica, Australia, and Thailand. They travel throughout the Pacific Ocean. Some, however, are found in the Gulf of Mexico.

Behavior

Like all dolphins, spinners are very intelligent. They are able to determine the direction, distance and size of their prey when they are hunting. They are also very social with each other and other creatures. Spinners “hang out” with each other and can be cliquey like a group of teenagers. They also baby-sit each other’s offspring. Some spinners even hug or stroke each other with their fins.

Spinner dolphins are basically nocturnal, meaning they sleep in the day and search for food at night. Spinner dolphins’ prey consists of fish, squid, and shrimp. Like other dolphins, spinners use echolocation to communicate with each other. Echolocation is a series of pulses and clicks released by the dolphin’s mouth. These sounds bounce off of objects and can be heard and interpreted by other dolphins.

Besides spinning, another unusual thing that spinners do is they associate with yellow fin tuna. They have been found to swim with schools of yellow fin tuna. They do not eat the tuna, they just swim with them. Marine biologists do not why they do this.

Degradation

This relationship between the spinners and tuna has been fatal to the species. Commercial tuna fishermen use the spinners as a mark to find schools of tuna. If the dolphins are in the way, they catch and kill them to get to the tuna. The actions of these fishermen have decreased the population of Costa Rican spinners by 90%. Millions of spinners have been killed all over since the 1950’s.

Thousands of dwarf spinners easily get caught in shrimp fishing nets and die. In some areas, spinner dolphins of all sizes are used for meat and bait.

Sources

www.sailhawaii,com/spinnerdolphins,html

www.dolphinheart.com/dolphin.html

www.ms-starship.com/scienceview/spinner_dolphin.html

www.wdcs.org

www.divinedolphin.com/spinners

www.greenreefbelize.com/reefbriefs

www.bbc.uk/nature

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Comments (5)
Jiri

Excellent article!

Jiri

Excellent article!

Jiri

Excellent article!

Jiri

Excellent article!

Jiri

Excellent article!

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