Common Name: Tucuxi
Class: Mammalia
Order: Cetacea
Family: Delphinidae
Genus: Sotalia
Species: Sotalia fluviatilis


Tucuxi belong to the Mammalian Order Cetacea, in the suborder Odontoceti. All toothed whales belong to the suborder Odontoceti, which is Latin for "toothed whales". This dolphin belongs to the oceanic dolphin family, Delphinidae. Other members of this family include the killer whale, long-beaked common dolphin, and pilot whale. The tucuxi's scientific name is Sotalia fluviatilis. The generic name, Sotalia, is of unknown origin. The specific name, fluviatilis, mean “of a river”, referring to the estuarine and riverine habitats preferred by this species. The animal’s common name “tucuxi”, pronounced “too-koo-shee”, is derived from the Tupi language of the Mayanas Indians. The Tupi and Guarani are the indigenous peoples of Coastal Brazil, the Amazon River, and Northeastern South America. Two ecotypes of this species exist, a riverine tucuxi, Sotalia fluviatilis fluviatilis, and a marine tucuxi, Sotalia fluviatilis guianensis. The riverine ecotype inhabits the Amazon River and its tributaries, while the marine ecotype lives throughout the coastal regions of Honduras to Brazil.


The tucuxi looks similar to the bottlenose dolphin, with bluish gray coloration dorsally, and lighter gray ventrally for the marine ecotype, and pinkish white for the riverine ecotype. However, the tucuxi differs drastically in size from the bottlenose dolphin. It is much smaller, usually growing no larger than six feet in length. In fact, the tucuxi is one of the two smallest species of Delphinidae. The other species is Hector’s dolphin, Cephalarhynchus hectori, which is endemic to the coast of New Zealand. The riverine ecotype is even smaller, growing to about four feet in length. The tucuxi ranges from 95-120lbs in weight.


The tucuxi’s range includes the Amazon River and its tributaries, as well as the coastal regions and estuaries of northeastern South America, along the Caribbean Sea and Atlantic Ocean. This species prefers a wide range of habitats, preying on a variety of noncommercial freshwater and saltwater fishes.



Tucuxis live in groups of 10-15 individuals, but it is not uncommon to see smaller groups consisting of a female and calf, or larger groups of 50-60 individuals. No social interactions between tucuxis and Amazon River dolphins, Inia geoffrensis, have been documented. Gestation is estimated at 11-12 months. Calving peaks in October and November for the riverine ecotype, during the low water period of the Amazon. The marine ecotype calves during the winter. Newborns are range 2-3ft in length.


The development of the Amazon River region greatly impacts this species. The construction of dams especially disrupts river ecology. Entanglement in fishing gear is also a threat. Fortunately, tucuxis do not compete with humans for the same fish species. Tucuxis prey on noncommercial fish species. Other human activities endanger dolphins, such as pollution. The worldwide population is unknown.


Content provided by Canisius College students under the direction of Michael Noonan, PhD.