Description: Giant otters have a gray or brown, dense (and waterproof) coat, which appears velvety when dry. Their muzzle is blunt and sloping; neck is muscular and long. Highly sensitive, long vibraissae (whiskers) protrude from the muzzle and forehead, aiding in the underwater search for prey. The muzzle and chest may be blotched with a pale coloring of varying degrees, sometimes forming a ‘bib’ effect. The pattern of blotches is unique to each individual and has been used by researchers to identify individual animals. Giant otters have large, powerful tails which are paddle-shaped. Their forefeet are shorter than their hindfeet; each foot has five toes with sharp non-retractile claws and webbing that extends to the tips of the toes.

Size: The largest of the 13 otter species, males can reach nearly six feet (1.8 m) in length while females measure 4.5 feet (1.4 m). Males can weigh up to 75 pounds (34 kg); females top weight is around 65 pounds (29.5 kg).

Behavior: Giant otters are very social animals. Their den is made by burrowing into banks or under fallen logs, They live and hunt in family groups (holts) of between four to ten members, earning them their local names of “Lobos del Rio” and “River wolves.” Each holt is led by a dominant female and each has a territory that does not overlap with other groups. They are powerful and graceful swimmers, spending most of their time in the water.

Diet: Giant otters mainly eat fish (piscivores) but frogs, snakes, crabs and crayfish may also be eaten, with each eating six to nine pounds (three to four kilos) daily.

Senses: Giant otters have very good vision. Their ears are small and round and like their nostrils, can be closed when underwater.

Communication: A variety of vocalizations are used to communicate among Giant otters. Since these otter hunt in packs, various non-vocal cues are used during the hunt or when defending their territory. They also use urine and feces to mark their territory.

Reproduction: Giant otters are monogamous with pairs staying together for life. Sexual maturity is attained at approximately two years of age. Females give birth to as many as five in each litter. Gestation lasts 65 to 70 days.

Habitat/range: Found in oxbow lakes and large slow moving rivers, including the Amazon, La Plate and Orinoco Rivers in north-central South America.

Status: CITES – Appendix I; IUCN Red List.  Endangered.  Included in AZA Species Survival Plan® (SSP). This program cooperatively manages specific, and typically threatened or endangered populations.