Giant Otter
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| Pteronura brasiliensis (Gmelin, 1788) |
The Giant Otter, Pteronura brasiliensis, (also known as the river wolf) is the largest of the world's otters, as well as the largest mustelid[1]. It is native to South America but is endangered and is also very rare in captivity.
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[edit] Physical characteristics
The Giant Otter can reach up to 6 ft (1.8 m) in length, and weigh 76 lb (34 kg) in weight. The females are smaller and weigh only 57–60 lb (26–27 kg). It has a lifespan of 12 years in their natural habitat, and 21 years in captivity.
Its fur is dense, thick and velvety, and is highly sought after by fur traders. The guard hairs are short, 5/16 in (8 mm) long, twice as long as the under-fur. The fur is water repellent and is a deep chocolate brown in colour. A unique white mark is located on the throat that can be used to distinguish between individuals. The head is round and the ears are small. The nose is completely covered in fur, with only the two slit-like nostrils visible. The eyes are large and acute, perfect for hunting underwater. The legs are short and stubby and end in large webbed feet tipped with sharp claws. The Giant Otter is well suited for an aquatic life, and can close its ears while underwater.
[edit] Feeding ecology
The Giant Otter is one of the largest predators of its region, and so can choose from a wide variety of animals to feed on. It feeds mainly on fish, such as catfish, piranha, and perch, but will also feed on crabs, small caimans, and snakes, including small anacondas. It can hunt both in groups and alone, tending to head towards the deeper waters while in groups. It consumes up to 10 lb (4.5 kg) of food each day, using mostly its eyesight to capture its prey.
The giant otter has very few natural predators. Caimans and large anacondas prey upon both young and adult otters by ambush. On land jaguars are also a threat to otters when they are in search of more suitable water reserves in the dry season. [2]
[edit] Social and reproductive biology
The Giant Otter is a highly social animal and lives in extended family groups of between 4-8 members. Group members share roles within the group, structured around the dominant breeding pair. The females have a gestation period of 65-70 days, giving birth to 1-5 young. Mothers give birth in an underground den near the river shore. Otter pups are taught to swim after two months and left to fend for themselves after two to three years. The Giant Otter is very sensitive to human activity, and tourists boating too close to a nursing mother can cause her so much stress that she stops producing milk, causing her young to starve. The Giant Otter gives birth annually. The Giant Otter is the only species of mustelid that is monogamous.[3]
[edit] Interactions with humans
The Giant Otter is known locally in Guyana as "Lobo del Rio" ("the river wolf") and in Brazil as "Ariranha".
It has been overhunted for its fur in the past.
The Philadelphia Zoo has the only productive breeding pair in the United States.
[edit] Conservation status
Vulnerable 1982-1996, Endangered since 1999.
[edit] References
- ^ Grzimek's Animal Life Encyclopedia, vol.XIV, pg.321a (2004).
- ^ Journey into Amazonia.
- ^ Grzimek's Animal Life Encyclopedia, vol.XIV, pg.324a (2004).
- Groenendijk et al (2004). Pteronura brasiliensis. 2006 IUCN Red List of Threatened Species. IUCN 2006. Retrieved on 11 May 2006. Database entry includes justification for why this species is endangered
- The giant otter featured in an NHNZ documentary entitled Pantanal: Land of Water
