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Spinner Dolphin

Stenella longirostris
Spinner Dolphins

Body color is gray/white with three distinct longitudinal swatches. They have long, slender snouts or beaks and their dorsal fin is triangular. A population of approximately 250 spinner dolphins inhabit the lagoon and nearshore waters at Midway Atoll.

Spinner dolphins are best known for their above-water displays of leaping and spinning several times on their body axis. Leaps can often be done in a series with as many as 14 leaps in a row. When within the Midway lagoon, spinner dolphins are seen predominantly resting and socializing. This low energy activity is characterized by slow and silent movement within a relatively limited area. Frequently, bursts of joyful play, with numerous leaps and spins, can also be seen.

Mating and calving occurs year-round, with gestation similar to that of most dolphins, around eleven months. Multiple males may mate with one female in short, consecutive intervals. Lactation often takes place for two years, but can also last for only one year. Calving intervals average three years. Females give birth to one calf. Newborns are closely monitored by their mother and several other adults. Babysitting is frequent. Nursing females with calves and several other grown females and large males form nursery groups, which increase the safety of young calves. These groups provide conditions where calves can learn skills important to their adult life.

Tiger and cookie-cutter sharks are the spinner dolphin's main predatory threat at Midway. Dolphins best avoid shark predation by staying in groups.

Facts About Spinner Dolphin

Diet
Spinner dolphins feed primarily at night on mid-water fishes and deep-water squid and shrimp, while resting for most of the daylight hours
Life Span
20 years
Size
Adults: length 2m (6- 7 ft) and weighing approximately 59-77 kg (130- 170 lbs); calves are approximately 66 cm (2 ft) long, have a pinkish tint and have been seen trying to spin
Page Photo Credits — Andy Collins/NOAA
Last Updated: Sep 11, 2013
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