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The Spinner dolphin gets it's name from it's incredible acrobatic skills, as it leaps from the water in high spinning aerial movements, though its scientific name originated in its reference to the dolphin's long snout, or rostrum - longirostrus, meaning long rostrum.

spinner01.jpg (8947 bytes)A slender body with its long narrow beak, the Spinner is known to exist in other forms - Costa Rican, Eastern Pacific and of course the Hawaiian form.   It's dorsal fin is dependant on either its age or geographical form, from falcate, to rounded to completely triangular and they have long and pointed flippers.     Colouration is also dependant on the geographic location with the Costa Rican and Eastern Pacific individuals mainly grey and other forms more generally two tone in colour appearance. The Whitebelly and Hawaiian Spinners' dorsal cape are a dark grey or black with paler flanks,  and a creamy white underside.

Here is a poem written by Terry Walker from Dolphinheart that describes the graceful and acrobatic ability of the Spinner Dolphin.

Key Facts of the   Spinner Dolphin:

Adult length:     All forms of Spinner dolphins measure  between 1.3 metres and 2.1 metres.

Adult weight:     Weight is generally around 45 kg to 75 kg.

Lifespan:    Unknown.

Habitat:     The Spinner is found in the tropical and sub-tropical waters all over the world.   They are known to live both inshore and offshore waters throughout the Pacific, Atlantic and Indian Oceans, preferring the warm temperate regions.     They are very common in the Hawaiian Islands.

Group size:    This dolphin is often been seen resting and travelling with numbers around 100 to 300, though groups of over 1,000 in offshore regions are reported.   Large groups then have smaller sub-groups that define individuals according to age, sex and behavioural activity.

Behaviour:   Highly social, Spinners often associate with other cetaceans such as Pilot Whales (Globicephala melas/macrorhynchus) and Spotted Dolphins (Stenella frontalis/attenuata).    Spinners are very acrobatic with their somersaults, high spinning leaps and many other aerial activities.    They often jump from the water and continuously spin, and their movements consist of a variety of leaps and spins, such as the tail over head leap.     They also enjoy bowriding on the pressure of the bow waves.  They are vocal in their whistles and clicks, and can swim as fast as 20 km per hour.      Spinners are particularly active toward dusk.     Below is a list and description of their various aerial movements and behaviour.

Leaps:   These dolphins often leap in the company of fast-moving schools, with the tail over head being the most common and vigorous.   The dolphin thrusts its entire body out of the water, throwing its tail over its head and landing tail first on its dorsal cape or back .

Tail Slaps:    This occurs when the dolphin slaps its tail flukes against the surface of the water while in either a normal or inverted position. Often a series involving more than 20 slaps at a time, these slaps usually occur in slow-moving, undisturbed schools and may signal a change in behaviour.

Head/Back/Side Slaps:     Dolphins travelling in moving schools are often seen rising as much as l/2 of their bodies out of the water, then slapping their back, side, or belly against the surface of the water. These slaps often happen in the direction of travel, and do not create the loud smacking sounds associated with tail slaps and spins

Spins:     This is what gives this dolphin its name.   Bursting from the water, and by twisting its neck and body, Spinners can perform as many as 7 rotations during a single leap that can take them as high as 2 metres in the air in just over one second.   Spins are often performed in a series.

Caressing:      This behaviour may include stroking one another with their pectoral fins, swimming belly to belly with another animal, or opening one's mouth and raking the other animal gently with the teeth (much like scratching).     This is one way that they communicate

Play Behaviour:     Dolphins are highly perceptive of their surrounding environment, and are often found playing with inanimate objects in both captivity and the wild.     Dolphins have frequently been seen using plastic bags, pieces of seaweed, or any other debris as objects to toss around, drag off one's pectoral fins or flukes, and exchange with other members, much like our "tag" or "catch." games.

Bow Riding:      Most species of dolphins are attracted to the pressure wave created by moving boats and is common behaviour as they ride on the bow waves and stern waves.    It is believed that this behaviour is for pure enjoyment or a free ride, much like body surfing in humans. 

Reproduction:     Gestation lasts for about ten to eleven months, and the female's complete reproduction cycle last two years.    She will give birth once every two to three years to a single calf, and will nurse her offspring for an approximate period of up to 18 months.    Sexual activity appears to be most active during summer, with mating involving more than one partner.

Calves:     Calves are around 77cm  in length at birth, and are fairly active in their groups.  They often chase, and roll over another in playful  behaviour, with adult Spinners close by.   Males will become sexually mature between the ages of 6 and 11 years when he will measure 1.7 metres, with females attaining sexual maturity when she reaches between 3 to 5 years, and measuring 1.65 metres.

Diet & Feeding:   The Spinner dolphin feeds on a variety of midwater fish and squid, often swimming with the spotted dolphin though it's feeding area usually goes much deeper.   Spinners are different in the fact that they are nocturnal in their feeding habits.

Noteable features:    This dolphin breathes many times per minute.   They have no fear of boats and approaches them with ease, often accompanying them for half an hour or more.   A speedy swimmer, the Spinner dolphin can travel at speeds of about 20 km per hour, with a top speed of around 37 km per hour.    It is believed that they can dive to a depth of 6 metres to feed.  There are a number of geographic varieties of the Spinner dolphin, though there are no sub-species.

Costa Rican form:    This Spinner dolphin form measures around 1.8 metres to 2.2 metres, weighing approximately 68 kg, with about 100 cone-shaped teeth on each jaw.    This form lives along the Pacific coasts of Central America.

Eastern Pacific form:    This form measures between 1.6 metres and 1.9 metres, with a weight of around 60 kg on average.  It frequently lives off the coast of the Pacific ocean of North America and can be found as far as 1,000 km from shore.

White-belly form:     The adult length is around 1.6 metres and 1.9 metres, with eight generally around 60 kg,  This dolphin is found off the coasts of Mexico, Central and South America.   It has been seem 300 to 800 km from shore.

Tropical Atlantic Ocean and Indian Ocean form:    This dolphin is about 1.8 metres in length but can reach 2 metres, weighing and estimated 82 kg.   It has between 92 and 130 small cone-shaped teeth on each jaw.   Found in the Atlantic's tropical waters, the Gulf of Mexico and the Indian Ocean.

Hawaiian form:     The most recognised and well-known of the Spinner dolphins, this adult measures between 1.7 metres and 2 metres, with an average weight of 90 kg.    This form if found in the warm temperate Hawaiian waters, although it has been recorded  as being seen to the east off San Diego.

Dwarfish form:     This type is known only from skeletons held in the Tokyo National Science Museum.   It's body size measuring 1.29 metres to 1.37 metres and weight between 21.5 kg and 26.5 kg.  Found only in the Gulf of Siam it is the smallest of the Spinners.  It's population status and size are unknown.

Threats:     Spinner dolphins are often targeted in the tuna fisheries of of the Eastern Pacific Ocean.   They are very often killed accidentally  in gill  nets and harpoon fisheries.   The Spinner dolphin only exists in the wild due to its inability to adapt because of their tight social bonds with others in their groups.

Population:   This dolphin is the most threatened by seine and tuna fishing, and this has damaged the population.  It is estimated that numbers have declined as much as 80% since seine fishing began in the 1960s.  The estimated current population status is therefore unknown.

 

Other Spinner Dolphin Facts:

Spinners are different from other dolphins that it feeds at night.

They are very acrobatic and highly social.

These dolphins can perform a series of spins as many as 7 rotations in a single leap!

Often associates with other cetaceans such as Pilot Whales, Pygmy Killer Whales, Spotted Dolphins and Melon Headed Whales.

It is a victim of mass stranding in Florida.

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