Facts About Spinner Dolphins
Acrobatic Displays
Spinner dolphins (Stenella longirostris) are named after their spectacular acrobatic displays, leaping out of the water and spinning in the air. They can spin round as many as seven times and like to ride the bow waves of boats.
Description
Spinners are also known as Long-beaked, or Long-nose dolphins from their nose shape. They are small and graceful and their size and coloring differs with geographic location. Their identifying features are their triangular shaped dorsal fin and their long, thin, snout.
Commonly their coloring is three-part. The back is of darkish grey, turning to a lighter grey on their sides and lightening in color to a lighter grey, or white underneath. A stripe of dark grey stretches from the eye to the flipper underneath a thin, light colored line. Spinner dolphins grow to around 129 – 235 cm in length and weigh between 23 – 78 kg.
Range and Habitat
Spinners can be found living in most tropical seas of the globe. They are also found in sub-tropical seas and warm temperate waters. They are also are at home in tropical high seas, or around shallow reef and coastal regions.
Sub-species
There are four known sub-species of Spinner dolphin which are recognised. They are Gray’s spinner dolphin (S. l. longirostris), which can be found in all tropical waters; the Eastern spinner dolphin (S. l. orientalis), found in the open tropical seas of the eastern Pacific; the Costa Rican, or Central American spinner dolphin (S. l. centroamericana), which swims off western Central America and Mexico; and the Dwarf spinner dolphin (S.l. roseiventris), inhabiting seas of Southeast Asia.
Social Animals
Spinner dolphins are social animals forming schools that may consist of a few individuals, or comprise of over a thousand individuals. They will also join up with other species such as Pantropical spotted dolphins and small toothed whales where they are known to migrate to warmer waters together.
Breeding
Courtship behaviour has been observed in Spinner dolphins with male and female caressing each other. Sexual maturity in females is reached when they are between 4 and 7 years of age. In males, sexual maturity is achieved between 7 and 10 years of age.Spinners have a gestation of around 10 months and calve every three years. The calf is nurtured by the mother for around two years and they form a lifelong bond.
Spinning Behaviour
The reason behind their spectacular spinning displays remains a mystery. One theory is that they spin to create clouds of bubbles the purpose of which is unclear, but this, and by splashing back in the water they may create an echolocation point that enables other dolphins to know where they are. There are also suggestions that they may be trying to rid themselves of suckerfish, or it may be that it is just a form of play.
Threats
In tropical parts of the eastern Pacific Ocean during the 1960s the Eastern spinner dolphin suffered greatly from commercial tuna fishing practices. Their population was reduced by around two-thirds of their original numbers.
Thanks to increasing public awareness and outrage at these practises measures were introduced to the fishing industry which has helped reduce deaths. However although the population has improved Spinners are still be caught up in fishing nets and although they are, or should be released, there are fears that it is causing instability in the population.
Spinner dolphins (Stenella longirostris) are named after their spectacular acrobatic displays, leaping out of the water and spinning in the air. They can spin round as many as seven times and like to ride the bow waves of boats.
Description
Spinners are also known as Long-beaked, or Long-nose dolphins from their nose shape. They are small and graceful and their size and coloring differs with geographic location. Their identifying features are their triangular shaped dorsal fin and their long, thin, snout.
Commonly their coloring is three-part. The back is of darkish grey, turning to a lighter grey on their sides and lightening in color to a lighter grey, or white underneath. A stripe of dark grey stretches from the eye to the flipper underneath a thin, light colored line. Spinner dolphins grow to around 129 – 235 cm in length and weigh between 23 – 78 kg.
Range and Habitat
Spinners can be found living in most tropical seas of the globe. They are also found in sub-tropical seas and warm temperate waters. They are also are at home in tropical high seas, or around shallow reef and coastal regions.
Sub-species
There are four known sub-species of Spinner dolphin which are recognised. They are Gray’s spinner dolphin (S. l. longirostris), which can be found in all tropical waters; the Eastern spinner dolphin (S. l. orientalis), found in the open tropical seas of the eastern Pacific; the Costa Rican, or Central American spinner dolphin (S. l. centroamericana), which swims off western Central America and Mexico; and the Dwarf spinner dolphin (S.l. roseiventris), inhabiting seas of Southeast Asia.
Social Animals
Spinner dolphins are social animals forming schools that may consist of a few individuals, or comprise of over a thousand individuals. They will also join up with other species such as Pantropical spotted dolphins and small toothed whales where they are known to migrate to warmer waters together.
Breeding
Courtship behaviour has been observed in Spinner dolphins with male and female caressing each other. Sexual maturity in females is reached when they are between 4 and 7 years of age. In males, sexual maturity is achieved between 7 and 10 years of age.Spinners have a gestation of around 10 months and calve every three years. The calf is nurtured by the mother for around two years and they form a lifelong bond.
Spinning Behaviour
The reason behind their spectacular spinning displays remains a mystery. One theory is that they spin to create clouds of bubbles the purpose of which is unclear, but this, and by splashing back in the water they may create an echolocation point that enables other dolphins to know where they are. There are also suggestions that they may be trying to rid themselves of suckerfish, or it may be that it is just a form of play.
Threats
In tropical parts of the eastern Pacific Ocean during the 1960s the Eastern spinner dolphin suffered greatly from commercial tuna fishing practices. Their population was reduced by around two-thirds of their original numbers.
Thanks to increasing public awareness and outrage at these practises measures were introduced to the fishing industry which has helped reduce deaths. However although the population has improved Spinners are still be caught up in fishing nets and although they are, or should be released, there are fears that it is causing instability in the population.
References and Attributions
Image File:Spinner dolphin jumping.JPG From Wikimedia Commons - Spinner dolphin - Image Author: Magnus Kjaergaard - Creative Commons Attribution 3.0 Unported license
Spinner dolphin From Wikipedia
ARKive - Spinner Dolphin
IUCN Red Book of Threatened Species
Image File:Spinner dolphin jumping.JPG From Wikimedia Commons - Spinner dolphin - Image Author: Magnus Kjaergaard - Creative Commons Attribution 3.0 Unported license
Spinner dolphin From Wikipedia
ARKive - Spinner Dolphin
IUCN Red Book of Threatened Species