Spinner dolphins (Stenella longirostris) are relatively small dolphins that were named for their unique behavior of leaping and spinning, a behavior which can be seen long distances away. These spins can involve more than 4 body revolutions (check out videos of spinner dolphins swimming and spinning on ARKive).
There are 4 subspecies of spinner dolphin: Gray's spinner dolphin (Stenella longirostris longirostris), Eastern spinner dolphin (S. l. orientalis), Central American spinner dolphin (S.l. centroamericana), and the dwarf spinner dolphin (S.l. roseiventris).
Spinner dolphins grow to 6-7 feet in length and 130-170 pounds in weight. Their beaks are long and slender. Coloration may vary depending on where they live, but they often have a striped appearance as they have a dark gray back, gray flanks and white underside. In some adult males, the dorsal fin looks as if has been stuck on backwards.
Spinner dolphins gather in pods that can number into the thousands. These animals may also associate with other marine life, including humpback whales, spotted dolphins and yellowfin tuna.
Habitat and Distribution:
The spinner dolphin has a year-round breeding season After mating, the female's gestation period is about 10-11 months, after which a single calf about 2.5 feet long is born. Calves nurse for 1-2 years.
The lifespan for spinner dolphins is estimated at about 20-25 years.
The spinner dolphin is listed as "data deficient" on the IUCN Red List. Spinner dolphins in the Eastern Tropical Pacific were caught by the thousands in purse seine nets targeting tuna, although their populations are slowly recovering due to mortality limits that have been placed on those fisheries.
Other threats include entanglement or bycatch in fishing gear, targeted hunts in the Caribbean, Sri Lanka, and the Philippines, and coastal development which affects the sheltered bays that these dolphins inhabit in some areas during the day.
References and Further Information:
- American Cetacean Society. Spinner Dolphin: Stenella longirostris (Short-Beaked) and Delphinus capensis (Long-Beaked). Accessed April 30, 2012.
- Culik, B. 2010. Odontocetes. The toothed whales: "Stenella longirostris". UNEP/CMS Secretariat, Bonn, Germany. Accessed April 30, 2012.
- Hammond, P.S., Bearzi, G., Bjørge, A., Forney, K., Karczmarski, L., Kasuya, T., Perrin, W.F., Scott, M.D., Wang, J.Y., Wells, R.S. & Wilson, B. 2008. Stenella longirostris. IUCN 2011. IUCN Red List of Threatened Species. Version 2011.2. Accessed April 30, 2012.
- Nelson, B. 2011. Why Does This Dolphin Have Its Fin On Backwards?. Mother Nature Network, Accessed April 30, 2012.
- NOAA Fisheries: Office of Protected Resources. Spinner Dolphin (Stenella longirostris). Accessed April 30, 2012.
- OBIS SEAMAP. Spinner Dolphin (Stenella longirostris). Accessed April 30, 2012.
- Perrin, W. 2012. Stenella longirostris (Gray, 1828). In: Perrin, W.F. World Cetacea Database. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=137109 on April 30, 2012.
- The Mammals of Texas. Spinner Dolphin. Accessed April 30, 2012.