Overview

Brief Summary

Biology

The giant South American turtle nests during the low water season, laying from 75 to 125 leathery eggs per clutch. Large groups of females return to the same sandy riverbanks and sandbars every year to nest in groups that are thought to decrease loss of eggs to predators due to the shear numbers present (8). The eggs take from 42 to 47 days to hatch (3), timed to avoid the rising of the rivers which will drown any unhatched turtles (8). As with most turtles, the sex of the hatchlings is determined by the average temperature at which they are incubated – females develop at higher temperatures and males develop at lower temperatures (3). This species is mainly herbivorous, feeding on aquatic vegetation and plant matter that falls into the water. However, it is also known to be somewhat opportunistic, feeding on small, slow-moving prey and carrion (3). Mutual cleaning behaviour between individuals of this species has been observed. One turtle will position itself at right angles to a second turtle and use its jaws to pull algae from its shell. The turtles will then switch position (2).
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Description

The giant South American turtle is the largest river turtle in South America (7). It has a broad, domed and streamlined carapace for active swimming in moderate river currents (3). The colour may be influenced by the algae that is attached to it (2), but is usually olive green to brown in colour (5). This turtle belongs in the family Pelomedusidae, which contains the side-necked turtles, and has a long neck which can be withdrawn horizontally within the shell, leaving it partly exposed, rather than retracting it in a vertical 'S' bend as in most other turtles (3).
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Distribution

Continent: South-America
Distribution: Caribbean drainages of Guyana and Venezuela, upper Amazon tributaries in Bolivia, Peru, Colombia, Venezuela, and Brazil, Ecuador, Trinidad.  
Type locality: South America.
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Historic Range:
South America_Orinoco R. and Amazon R. basins

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Range

This turtle is found in the Amazon River drainages of South America, as far south as northern Brazil and northern Peru and as far west as eastern Peru. It is also found on the Islands of Trinidad and Tobago (1) (6).
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Ecology

Habitat

Habitat and Ecology

Habitat and Ecology
Semi-aquatic - large rivers and tributaries, adjacent lagoons and forest ponds.

Systems
  • Terrestrial
  • Freshwater
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The giant South American turtle inhabits freshwater rivers with sandy banks or sandbars, which are crucial for nesting (3).
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Life History and Behavior

Life Expectancy

Lifespan, longevity, and ageing

Maximum longevity: 25.3 years (captivity)
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Molecular Biology and Genetics

Molecular Biology

Statistics of barcoding coverage: Podocnemis expansa

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 0
Specimens with Barcodes: 1
Species With Barcodes: 1
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Conservation

Conservation Status

IUCN Red List Assessment


Red List Category
LR/cd
Lower Risk/conservation dependent

Red List Criteria

Version
2.3

Year Assessed
1996
  • Needs updating

Assessor/s
Tortoise & Freshwater Turtle Specialist Group

Reviewer/s

Contributor/s

History
  • 1994
    Endangered (E)
  • 1990
    Endangered (E)
  • 1988
    Endangered (E)
  • 1986
    Endangered (E)
  • 1982
    Endangered (E)
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Current Listing Status Summary

Status: Endangered
Date Listed: 06/02/1970
Lead Region: Foreign (Region 10) 
Where Listed: Entire


Population detail:

Population location: Entire
Listing status: E

For most current information and documents related to the conservation status and management of Podocnemis expansa , see its USFWS Species Profile

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Status

The giant South American turtle is classified as Lower Risk – conservation dependent (LR/cd) on the IUCN Red List 2003 (1) and is listed under Appendix II of CITES (3).
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Threats

Threats to this species include poaching of females, collection of eggs and hatchlings, accidental and intentional capture (for food and oil) of adult turtles by fishermen, urban and industrial development near nesting sites, and lack of conservation education (9). Logging and clearing of areas surrounding rivers and damming of rivers can cause the water cycle to be drastically altered. This can confuse the turtles' natural seasonal cycle of nesting which is timed to the alternation of floods and low flows. In addition, premature rising of rivers can flood nesting sites causing reduced hatching success (8). Climate change can potentially threaten turtle species as the sex of offspring is determined by the temperature at which they are incubated. Should the temperature rise 2 ºC, the ratio of males to females could be severely skewed, and a rapid rise of 4 ºC could possibly eliminate males altogether. Turtles are seen as indicator species that can reveal the effects of climate change on the natural world (10).
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Management

Conservation Actions

Conservation Actions
It is listed on CITES Appendix II.
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Conservation

With high reproductive potential, the giant South American turtle is expected to be capable of rapid recovery in areas with limited human presence and an environmental management plan. The management plan implemented at Middle Orinoco River has included the protection of nesting beaches, a nursery program for the care and release of hatchlings, and an environmental education program for the public. It has resulted in the slowed decline of nesting turtles and a modest increase in total turtle numbers since 1992 (9). In addition, research has showed that eggs in a clutch laid by one mother may have different fathers, which helps to increase genetic variation and reduces the prevalence of inbreeding defects that result from small populations (11)
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Wikipedia

Arrau turtle

"Arrau" redirects here. For the pianist, see Claudio Arrau.

The Arrau River turtle, South American river turtle,[2] or Giant South American turtle[1] (Podocnemis expansa), also known as the Charapa turtle, Arrau turtle, tartaruga-da-amazônia, or Araú, is the largest of the side-neck turtles (Pleurodira).

The turtles are found in the Amazon Basin (Peru, Brazil, Colombia, Venezuela, etc.). Adults often reach 1 m in length. Females have wide flattened shells and are larger and more numerous than the males. Adult Arraus feed entirely on plant food. The nesting habits of this species are similar to those of their sea turtle kindred. Like sea turtles they gather in huge numbers to travel to suitable nesting areas. The females lay their eggs on sandbanks that are exposed only in the dry season but there are relatively few such sites. The females come out on the sandbanks at night to lay their eggs, which can number anywhere from 90 to 100 soft-shelled eggs. They then return to their feeding grounds.

When hatched, the young are around 5 cm long and dart directly for the water, but they emerge to the attentions of many predators so that only about five percent ever reach the adult feeding grounds. Because of this it is an endangered species and is protected in some areas.[1][3] Arrau turtles are captive bred in facilities, along with other endangered reptiles such as the Orinoco crocodile.[4]

References[edit]

  1. ^ a b c Tortoise & Freshwater Turtle Specialist Group 1996. Podocnemis expansa. In: IUCN 2011. IUCN Red List of Threatened Species. Version 2011.2. www.iucnredlist.org. Downloaded on 25 May 2012.
  2. ^ Podocnemis expansa, The Reptile Database
  3. ^ The Simon and Schuster Encyclopedia of Animals
  4. ^ "Venezuela’s Fitful Effort to Save a Scaly Predator", The New York Times, December 25, 2013 
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