La Plata Dolphin
Encyclopedia
The La Plata Dolphin or Franciscana (Pontoporia blainvillei) is found in coastal Atlantic waters of southeastern South America
. Taxonomically it is a member of the river dolphin
group and the only one that actually lives in the ocean and saltwater estuaries
, rather than inhabiting exclusively freshwater systems.
and Alcide d'Orbigny
in 1844 (the species epithet blainvillei commemorates the French zoologist Henri Marie Ducrotay de Blainville
). The La Plata Dolphin is also widely known as the Franciscana - the Argentine
and Uruguay
an name that has been adopted internationally. Other common names are the Toninha (the Brazil
ian name) and Cachimbo.
has a long base and a rounded tip.
The La Plata Dolphin weighs up to 50 kg (110 lb) and lives for up to 20 years. The gestation period is around 10–11 months and juveniles take just a few years to mature. Females may be giving birth by the age of five.
, squid
and shrimp
. They are, themselves, hunted by orca
and several species of shark
.
, including the Río de la Plata
estuary
. Its distribution ranges from the Tropic of Capricorn
near Ubatuba, Brazil
, south to Península Valdés, Argentina
. It is the only member of the river dolphin group that actually lives in the ocean and saltwater estuaries
, rather than freshwater. Although some members of the species do spend portions of their lives outside of river systems, there are many individuals who live their entire lives within rivers, never venturing into the ocean proper.
The species is listed on Appendix I and Appendix II of the Convention on the Conservation of Migratory Species of Wild Animals (CMS). It is listed on Appendix I as this species has been categorized as being in danger of extinction throughout all or a significant proportion of their range and CMS Parties strive towards strictly protecting these animals, conserving or restoring the places where they live, mitigating obstacles to migration and controlling other factors that might endanger them. It is listed on Appendix II as it has an unfavourable conservation status or would benefit significantly from international co-operation organised by tailored agreements.
A young La Plata dolphin was rescued in 2011 off of Montevideo, Uruguay. Images of the infant dolphin became viral on Facebook, highlighting the plight of the species. http://www.buzzfeed.com/mjs538/adorable-pictures-of-man-taking-care-of-an-orphane
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
. Taxonomically it is a member of the river dolphin
River dolphin
River dolphins are the four living species of dolphin that reside in freshwater rivers and estuaries. River dolphins inhabit areas of Asia and South America. They are classed in the Platanistoidea superfamily of cetaceans. Three species live in fresh water rivers. The fourth species, the La Plata...
group and the only one that actually lives in the ocean and saltwater estuaries
Estuary
An estuary is a partly enclosed coastal body of water with one or more rivers or streams flowing into it, and with a free connection to the open sea....
, rather than inhabiting exclusively freshwater systems.
Taxonomy
The La Plata Dolphin is the only species in its genus, and is often placed in its own family, the Pontoporiidae. It was first described by Paul GervaisPaul Gervais
For the Canadian parliamentarian see Paul Mullins GervaisPaul Gervais full name François Louis Paul Gervaise was a French palaeontologist and entomologist.-Biography:...
and Alcide d'Orbigny
Alcide d'Orbigny
Alcide Charles Victor Marie Dessalines d'Orbigny was a French naturalist who made major contributions in many areas, including zoology , palaeontology, geology, archaeology and anthropology....
in 1844 (the species epithet blainvillei commemorates the French zoologist Henri Marie Ducrotay de Blainville
Henri Marie Ducrotay de Blainville
Henri Marie Ducrotay de Blainville was a French zoologist and anatomist.Blainville was born at Arques, near Dieppe. In about 1796 he went to Paris to study painting, but he ultimately devoted himself to natural history, and attracted the attention of Georges Cuvier, for whom he occasionally...
). The La Plata Dolphin is also widely known as the Franciscana - the Argentine
Argentina
Argentina , officially the Argentine Republic , is the second largest country in South America by land area, after Brazil. It is constituted as a federation of 23 provinces and an autonomous city, Buenos Aires...
and Uruguay
Uruguay
Uruguay ,officially the Oriental Republic of Uruguay,sometimes the Eastern Republic of Uruguay; ) is a country in the southeastern part of South America. It is home to some 3.5 million people, of whom 1.8 million live in the capital Montevideo and its metropolitan area...
an name that has been adopted internationally. Other common names are the Toninha (the Brazil
Brazil
Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...
ian name) and Cachimbo.
Description
The La Plata Dolphin has the longest beak (as a proportion of body size) of any cetacean — as much as 15% in older adults. Males grow to 1.6 m (5 ft, 3 in) and females to 1.8 m (5 ft, 10 in). The body is a greyish brown colour, with a lighter underside. The flippers are also very large in comparison with body size and are very broad, but narrow on joining the body and so are almost triangular in shape. The trailing edges are serrated. The crescent-shaped blowhole lies just in front of a crease in the neck, giving the impression that dolphin forever has its head cricked upwards. The dorsal finDorsal fin
A dorsal fin is a fin located on the backs of various unrelated marine and freshwater vertebrates, including most fishes, marine mammals , and the ichthyosaurs...
has a long base and a rounded tip.
The La Plata Dolphin weighs up to 50 kg (110 lb) and lives for up to 20 years. The gestation period is around 10–11 months and juveniles take just a few years to mature. Females may be giving birth by the age of five.
Behavior and Feeding
The animal is very inconspicuous - it moves very smoothly and slowly—and can be difficult to spot unless estuary conditions are very calm. They will commonly swim alone or in small groups. Exceptionally groups as large as 15 have been seen. La Plata Dolphins are bottom feeders and gut inspections have revealed they eat at least 24 different species of fish, depending on which species are most common. They will also take octopusOctopus
The octopus is a cephalopod mollusc of the order Octopoda. Octopuses have two eyes and four pairs of arms, and like other cephalopods they are bilaterally symmetric. An octopus has a hard beak, with its mouth at the center point of the arms...
, squid
Squid
Squid are cephalopods of the order Teuthida, which comprises around 300 species. Like all other cephalopods, squid have a distinct head, bilateral symmetry, a mantle, and arms. Squid, like cuttlefish, have eight arms arranged in pairs and two, usually longer, tentacles...
and shrimp
Shrimp
Shrimp are swimming, decapod crustaceans classified in the infraorder Caridea, found widely around the world in both fresh and salt water. Adult shrimp are filter feeding benthic animals living close to the bottom. They can live in schools and can swim rapidly backwards. Shrimp are an important...
. They are, themselves, hunted by orca
Orca
The killer whale , commonly referred to as the orca, and less commonly as the blackfish, is a toothed whale belonging to the oceanic dolphin family. Killer whales are found in all oceans, from the frigid Arctic and Antarctic regions to tropical seas...
and several species of shark
Shark
Sharks are a type of fish with a full cartilaginous skeleton and a highly streamlined body. The earliest known sharks date from more than 420 million years ago....
.
Range and habitat
The La Plata Dolphin is found in the coastal Atlantic waters of southeastern South AmericaSouth America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
, including the Río de la Plata
Río de la Plata
The Río de la Plata —sometimes rendered River Plate in British English and the Commonwealth, and occasionally rendered [La] Plata River in other English-speaking countries—is the river and estuary formed by the confluence of the Uruguay River and the Paraná River on the border between Argentina and...
estuary
Estuary
An estuary is a partly enclosed coastal body of water with one or more rivers or streams flowing into it, and with a free connection to the open sea....
. Its distribution ranges from the Tropic of Capricorn
Tropic of Capricorn
The Tropic of Capricorn, or Southern tropic, marks the most southerly latitude on the Earth at which the Sun can be directly overhead. This event occurs at the December solstice, when the southern hemisphere is tilted towards the Sun to its maximum extent.Tropic of Capricorn is one of the five...
near Ubatuba, Brazil
Brazil
Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...
, south to Península Valdés, Argentina
Argentina
Argentina , officially the Argentine Republic , is the second largest country in South America by land area, after Brazil. It is constituted as a federation of 23 provinces and an autonomous city, Buenos Aires...
. It is the only member of the river dolphin group that actually lives in the ocean and saltwater estuaries
Estuary
An estuary is a partly enclosed coastal body of water with one or more rivers or streams flowing into it, and with a free connection to the open sea....
, rather than freshwater. Although some members of the species do spend portions of their lives outside of river systems, there are many individuals who live their entire lives within rivers, never venturing into the ocean proper.
Conservation
The La Plata Dolphin is listed as "Vulnerable" in the IUCN Red List of Threatened Species. However the Franciscana is a particular conservation concern because of its restricted distribution and vulnerability to incidental capture in fishing gear. Large numbers are killed in gillnets. Although the largest documented catches in the 1970s were in Uruguay, catches in recent decades have also been high in southern Brazil and Argentina. Scientists from all three countries have voiced their concerns, and asked for international assistance in highlighting the plight of the dolphin (see Reeves et al., pg. 53).The species is listed on Appendix I and Appendix II of the Convention on the Conservation of Migratory Species of Wild Animals (CMS). It is listed on Appendix I as this species has been categorized as being in danger of extinction throughout all or a significant proportion of their range and CMS Parties strive towards strictly protecting these animals, conserving or restoring the places where they live, mitigating obstacles to migration and controlling other factors that might endanger them. It is listed on Appendix II as it has an unfavourable conservation status or would benefit significantly from international co-operation organised by tailored agreements.
A young La Plata dolphin was rescued in 2011 off of Montevideo, Uruguay. Images of the infant dolphin became viral on Facebook, highlighting the plight of the species. http://www.buzzfeed.com/mjs538/adorable-pictures-of-man-taking-care-of-an-orphane
External links
- ARKive - images and movies of the Franciscana (Pontoporia blainvillei)
- Dolphins, Whales and Porpoises: 2002-2010 Conservation Action Plan for the World's Cetaceans, Reeves, Smith, Crespo and Notarbartolo di Sciara. Available online at http://www.iucn.org/themes/ssc/actionplans/cetaceans/cetaceans.pdf.
- Convention on Migratory Species page on the Franciscana / La Plata Dolphin