Cetacean Society International

Working for whales, dolphins and porpoises worldwide

CSI Photo Gallery


Tucuxi

(Sotalia fluviatilis)

The Tucuxi are very adaptable dolphins, some living 2,500 kilometers up the murky fresh water of the Amazon River, some in clear coastal sea waters from Panama to Southern Brazil, and others in the polluted estuaries and rivers along eastern Central and South America. The larger marine subspecies lives near the coasts from Nicaragua to southern Brazil, wherever the water is warm enough. They are called Tucuxi (pronounced "toó-koo-shee") in Brazil, and that has become their common name. Only about 30 inches (0.8 meters) long at birth, the adult marine Tucuxi only grows to about six and one-half feet (2.1 meters) long, with females larger than males. (Photo courtesy Fundación Omacha, Colombia.)
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The smaller freshwater subspecies of Tucuxi, which grows only to about 5 feet (1.5 meters), lives in the extensive Amazon River Basin, including much of the Orinoco River. Like this leaping dolphin, they often have a pinkish color extending over the pectoral fin. Known by many local names, such as bufeos in Peru, or toninas in Venezuela, they range inland into Colombia, Ecuador and right up to the eastern Andes Mountains in Peru. As the rivers flood seasonally the dolphins often hunt in submerged tropical forests. It's thought that their babies are usually born after a ten-month gestation, during the low water season, probably because fish are more concentrated in shallow pools and easier to hunt. (Photo courtesy Fundación Omacha, Colombia.)
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These Tucuxi are hunting small schooling fish in the busy harbor of Rio de Janeiro, Brazil. The noise and pollution of the harbor are constant, and just down the coast an oil refinery shares their habitat. Ever watchful for nets and boats, they tend to be very wary here, but in wilder places they may be approached and studied more closely. Where this dolphin shares its coastal habitat with increasing human populations much research is focused on human impacts and management solutions. Much of the CSI-supported research by local scientists has also included photo-ID catalogues of individuals, to understand how many there are, what their social structure is like, and how they use their habitat.
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Like this young dolphin, Tucuxi are often seen jumping or splashing, perhaps in play. Some populations seem to be very social, often living in small groups of from two to ten dolphins. Groups of up to 30 are seen in the oceans. Current research is studying how they use social sounds to communicate, and whether those sounds differ by group, population or region. How are group members related? How long do they stay together? Do they cooperate to hunt or guard against dangers? As the previously unknown Tucuxi accept the presence of careful researchers we will learn much more about their lives and societies. (Photo courtesy Marcos César Santos, Brazil)
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This Tucuxi calf was born playful and carefree, like all babies. She may be very curious, but these adults have learned to stay clear of boats and nets. They are wary because humans in boats may have hurt them, perhaps intentionally. They have much to teach the young, including how to avoid the harm that humans can bring. In some places mothers may raise their calves by themselves very near shore, rather than in a group like this, but why? In less than a decade we have learned so much about the Tucuxi, partly because so many young scientists are now doing research in Latin America, and this species seems to be almost everywhere. (Photo courtesy Marcos César Santos, Brazil)
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