OTHER COMMON NAMES
English: Arrau, large South American river turtle; French: Podocnémide élargie; German: Arrauschildkröte; Spanish: Arrau.
South American river turtles are massive sideneck turtles, up to 42.1 in (107 cm) in shell size, with a broad, flat carapace that’s wider posteriorly than anteriorly, often having two barbels on the chin, a broad cranium, and with the entrance of the higher jaw squared off (as opposed to notched or rounded). Juveniles have massive lemon-yellow spots on the top inside that are one or two black spots.
Orinoco and Amazon River basins of northern South America.
These turtles primarily inhabit massive rivers, however will enterprise into flooded areas adjoining to rivers throughout excessive water.
This species migrates appreciable distances up or down rivers to localized, colonial nesting seashores. Two to three weeks prior to nesting, females bask on sand seashores within the morning and the late afternoon.
FEEDING ECOLOGY AND DIET
This primarily herbivorous species apparently feeds predominantly on the fruits of riparian bushes. Leaves and stems are additionally taken, as are freshwater sponges and occasional bugs.
Courtship has not been described, however DNA research reveal that eggs in the identical clutch are sometimes fertilized by completely different males. As water ranges subside after the height of the wet season, females migrate to the primary river channels and upstream or downstream to sandbars to nest. The nesting season is brief, lasting solely 10–60 days (sometimes 25–45) in February and March on the Orinoco, and September to October (and even December), at numerous Amazon River branches. Most nesting happens at night time, after midnight. Females use all 4 limbs to excavate a physique pit about 3.Three ft (1 m) in diameter and 1.6 ft (0.5 m) deep. They then excavate the precise nest chamber within the backside of this pit, utilizing solely the hind limbs. Following egg laying, the feminine covers the chamber and often fills the physique pit, in both case utilizing her hind limbs. This species is exclusive in its household in producing eggs which can be practically spherical, averaging 1.6 in (four cm) in diameter. However, females often produce one or two “giant” eggs, which could be as massive as 3.2 in (eight cm) in longest diameter. Clutch measurement ranges from 48 to 156 eggs, though round 80 is typical. Larger females lay bigger clutches of bigger eggs, that are buried deeper than these produced by smaller females. Only a single clutch is laid per 12 months. Incubation is speedy within the very heat sand of the nesting seashores, requiring solely about 45 days. Over the next two to three days, the hatchlings dig out as a gaggle, usually rising at night time or within the early morning to keep away from lethally excessive floor temperatures. This species reveals temperature-dependent intercourse willpower, with temperatures above 90.7°F (32.6°C) producing females, and temperatures under that producing largely males; nevertheless, females could also be produced once more at nonetheless cooler temperatures. The pivotal temperature of 90.7° (32.6°C) is the best recognized for any turtle.
This species is listed as Lower Risk/Conservation Dependent by the IUCN. Exploitation by people has just about eradicated this turtle from many of the higher Amazon River basin, and populations across the vary are a lot diminished, regardless of nationwide authorized safety and concerted efforts to defend the remaining nesting seashores from disturbance, harvesting, predation, and flooding.
SIGNIFICANCE TO HUMANS
Adults and even hatchlings are harvested for his or her flesh, and eggs are collected for the oil that may be extracted from them. This harvesting is technically unlawful and on the native subsistence stage, nevertheless it stays to be seen whether or not this species can ever get better from the final 4 centuries of overexploitation.