There are five extant species of river dolphins. Suspended particles should often greatly reduce visibility in these habitats, specifically when the sediment is disturbed. The term dolphin usually refers to the extant families Delphinidae, Platanistidae, Iniidae, and Pontoporiidae, and the extinct Lipotidae. In addition to staying near coastal environments small dolphins are also known to travel in large groups in order to protect themselves from predators. The other two adults rammed the calf, held it under water, then threw it into the air and held it under water again. Sotalia guianensis. Studies of growth layers suggest the species can live up to 30 years. IUCN conservation status: Near Threatened. Since all dolphin species possess echolocation they can use this highly important ability to navigate the ocean, search for prey and get an early warning sign for nearby predators looking to turn them into a meal. up to 22,000 pounds . It is listed on Appendix II[13] as it has an unfavourable conservation status or would benefit significantly from international co-operation organised by tailored agreements. The short-beaked common dolphin is also abundant in the Black Sea, Gulf of Mexico, and Red Sea. It was first known to science in 1937, being named by W. R. B. Oliver after George Shepherd, curator of the Wanganui Museum, who collected the type specimen near Ohawe on the south Taranaki coast of New Zealand's North Island, in 1933. It's not known what the population size of Guiana dolphins is. Description The Guiana Dolphin is similar to the bottlenose dolphin but smaller and chunkier with a medium-length, narrow beak and a low, triangular dorsal fin with a long base.It is generally pale grey, blue-grey or brownish-grey with a paler underside often tinged pink … Rural Federal University of Rio de Janeiro, https://dx.doi.org/10.2305/IUCN.UK.2018-2.RLTS.T181359A50386256.en, "Proposed English common name for the neotropical delphinid Sotalia guianensis (P.-J. Guiana dolphins are very inconspicuous, and they do not bow ride on boats and normally swim away from them. Download : Download full-size image. [12] Infanticide has been reported twice before in bottlenose dolphins but is thought to be generally uncommon among cetaceans. The long-beaked common dolphin is a species of common dolphin. However, it is typically smaller, at only up to 2.1 m (6.9 ft) in length. River dolphins, alongside other cetaceans, belong to the clade Cetartiodactyla, with even-toed ungulates, and their closest living relatives the hippopotamuses, from which they diverged about 40 million years ago. In both species, the eyes are large, and there is black countershading around the eyes. The dolphin is coloured light to bluish grey on its back and sides. They school in very shallow waters, and are rarely found deeper than 16 m. Secchi, E., Santos, M. & Reeves, R. 2018. The dorsal fin is typically slightly hooked, with a triangular shape. It can live in both saltwater and freshwater. [3], Although described as species distinct from the tucuxi Sotalia fluviatilis by Pierre-Joseph van Bénéden in 1864, the costero Sotalia guianensis has subsequently been synonymized with Sotalia fluviatilis with the two species being treated as subspecies, or marine and freshwater varieties. They may belong either to the more commonly known family Delphinidae, which includes all oceanic dolphins, or to the family Platanistidae, which includes the river dolphins. Support WDC by shopping for yourself or a friend. Dolphins have been a mystery and a source of fascination for mankind for thousands of years. It has been reported as far south as southern Brazil and north as far as Nicaragua. The whale has not been studied extensively. They follow the gulf stream up to Norwegian waters. It is also found in the Caribbean and Mediterranean Seas. These dolphins live off the coast of New Zealand, and the average adult weight of these small mammals is 88 to 132 pounds (40 to 60 kilograms). Males reach sexual maturity at 6-7 years of age and females mature at 5-7 years. It can live in both saltwater and freshwater. The population of the Caravelas River estuary, eastern Brazil, was systematically monitored through a long‐term mark‐recapture experiment (2002–2009). Guiana dolphins are very inconspicuous, and they do not bow ride on boats and normally swim away from them. [9], More than 60 species of demersal and pelagic schooling fish have been reported as prey. Extant river dolphins are placed in two superfamilies, Platanistoidea and Inioidea. As adults, females are almost always larger than males. It has a larger range than the long-beaked common dolphin, occurring throughout warm-temperate and tropical oceans, including the Indian Ocean although in smaller numbers than other places they are found. The beak is well-defined and of moderate length. While it is true that the killer whale can consume a variety of marine mammals as well as fish and squid, most dolphins stick to a diet that consists of fish, squid, octopus and various crustaceans regardless of their size. Guiana dolphin whistles ranged in frequency from 1.7 to 66.7 kHz. This finding was reiterated by Caballero and colleagues[7] with a larger number of genes. Different dolphin communities may adopt their own foraging strategies based on local circumstances. They make short dives, lasting anything from only five seconds to two minutes. They are light grey to bluish grey on the back and pinkish to light grey on the belly. These mammals vary greatly in size, with their length ranging from than 4 to 30 feet and their weight ranging from 88 lbs. By continuing you agree to the use of cookies. Sotalia dolphins show a variety of aerial behaviors such as full leaps, somersaults, fluke-ups, spy-hopping, surface rolling, and porpoising. It is a member of the oceanic dolphin family (Delphinidae). [12], The costero is listed on Appendix II[13] of the Convention on the Conservation of Migratory Species of Wild Animals (CMS). The Guiana dolphin is found in coastal shallow waters and estuaries along the Atlantic coast of South and Central America, from southern Brazil in the south to Nicaragua in the north. There is a lighter area on the flank between the flippers and the dorsal fin and another mid-body at the level of the anus. Rural Federal University of Rio de Janeiro, https://dx.doi.org/10.2305/IUCN.UK.2018-2.RLTS.T181359A50386256.en, "Proposed English common name for the neotropical delphinid Sotalia guianensis (P.-J. [4] The first to reassert differences between these two species was a three-dimensional morphometric study of Monteiro-Filho and colleagues. One of the larger dolphins that is still called a dolphin in the common tongue is Risso’s dolphin, which is also known as Grampus. Some individuals can reach 18 cm, with the average closer to 12 cm. The IUCN Red List of Threatened Species 2018: e.T181359A50386256. Guiana dolphins perform impressive acrobatics including full leaps, spy hops, lobtails, flipper slaps, fluke-ups, surface rolls and porpoising.