Giant Otter

Giant Otter

Lobo de Rio (the River wolf), Los Lobos del Rio (Wolves of the River), Ariranha, Giant river otter

Kingdom
Phylum
Subphylum
Class
Order
Suborder
Family
Genus
SPECIES
Pteronura brasiliensis
Population size
Unknown
Life Span
8-19 years
Top speed
15
9
km/hmph
km/h mph 
Weight
22-32
48.4-70.4
kglbs
kg lbs 
Length
1-1.7
3.3-5.6
mft
m ft 

The Giant otter (Pteronura brasiliensis) is a South American carnivorous mammal. It is the longest member of the weasel family, Mustelidae, a globally successful group of predators. The Giant otter has no serious natural predators other than humans, although it must compete with other predators, such as the Neotropical otter, jaguar, and various crocodilian species, for food resources.

Appearance

The Giant otter is clearly distinguished from other otters by morphological and behavioral characteristics. It has the greatest body length of any species in the mustelid family. The Giant otter has the shortest fur of all otter species; it is typically chocolate brown but may be reddish or fawn, and appears nearly black when wet. The fur is extremely dense, so much so that water cannot penetrate the skin. Guard hairs trap water and keep the inner fur dry; the guard hairs are approximately 8 millimeters (one-third of an inch) in length, about twice as long as the fur of the inner coat. Its velvety feel makes the animal highly sought after by fur traders and has contributed to its decline. Unique markings of white or cream fur color the throat and under the chin, allowing individuals to be identified from birth. Giant otter muzzles are short and sloping and give the head a ball-shaped appearance. Their ears are small and rounded. The nose (or rhinarium) is completely covered in fur, with only the two slit-like nostrils visible. The Giant otter's highly sensitive whiskers (vibrissae) allow the animal to track changes in water pressure and currents, which aids in detecting prey. The legs are short and stubby and end in large webbed feet tipped with sharp claws. Well suited for aquatic life, it can close its ears and nose while underwater.

Video

Distribution

Geography

This species is a native of South America (except for Chile), east of the Andes. Currently, there are almost none in Argentina and Uruguay, and they are very rare in Paraguay. They are seen within the Amazon, Orinoco, and La Plata River systems and are found in slow-moving streams and rivers, lakes, swamps, and marshes, as well as flooded forests during the rainy season. Giant otters prefer habitats with non-floodable banks that have vegetation cover and where there is easy access to hunting places in relatively shallow waters.

Giant Otter habitat map

Climate zones

Giant Otter habitat map
Giant Otter
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Habits and Lifestyle

Giant otters are diurnal highly social animals; they live together in family groups numbering 2-20 individuals. A family has a home range of 12 sq. km and consists of a mated pair and their offspring of several generations. The family members clear an area beside a stream for their living quarters, of up to 50 sq meters, usually near feeding sites. Sizeable burrows are then built under fallen logs. One to five latrines for communal use are placed along the perimeter of the site. The established territory is then marked by the scent from the animals' anal glands. If intruders invade the family's territory, the parents will defend it and their family members. Within groups, otters are extremely peaceful and cooperative. They groom each other, rest, and may even hunt together. Giant otters are especially noisy and have a complex repertoire of vocalizations. Quick ‘hah’ barks or explosive snorts suggest immediate interest and possible danger. A wavering scream may be used in bluff charges against intruders, while a low growl is used for aggressive warning. They will also make hums and coos, and whistles. Newborn pups squeak to elicit attention, while older young whine and wail when they begin to participate in group activities.

Seasonal behavior

Diet and Nutrition

Giant otters are strictly carnivorous (piscivorous) and mainly fish such as cichlids, perch, characins (such as piranha), and catfish. If fish are unavailable, they will also take crabs, snakes, and even small caimans and anacondas.

Mating Habits

MATING BEHAVIOR
REPRODUCTION SEASON
year-round, peak in late spring-early summer
PREGNANCY DURATION
65-70 days
BABY CARRYING
1-5 pups
INDEPENDENT AGE
3-4 months
FEMALE NAME
female
MALE NAME
male
BABY NAME
whelp, pup

This species is monogamous, and pairs stay together for life. Reproductive behavior has largely been documented by observations of captive animals. Although some breeding occurs throughout the year, the peak of the breeding season is from late spring to early summer. Gestation lasts 65-70 days and the altricial young are born in late August until early October. There are 1-5 pups in a litter (usually 2-3) and they stay in the family den until they are 2-3 weeks old. They can open their eyes after 1 month and start to regularly follow their parents out of the den. Young are weaned at the age of 3-4 months. At 9-10 months they can hunt independently and look just like their parents. Reproductive maturity is reached when they are 2 years old.

Population

Population threats

Habitat fragmentation and loss, as well as pollution, are the current major threats to the Giant otter, as the areas where they live are degraded and destroyed by logging, mining, and damming. This species was excessively hunted up until the late 1970s for its valuable fur. Illegal killing still occurs, often at the hands of fishermen, who see Giant otters as competition for fish. Some pups in the wild are taken for pets and usually die because of the inexperience of caretakers.

Population number

The IUCN Red List has no current estimate for the total Giant otter population. There are estimates for the populations of a few areas: 2,000-5,000 individuals in the Brazilian Pantanal; 180-400 individuals in Madre de Dios, southeastern Peru; 31 individuals in Cantao State Park, Brazil; 75 individuals in Amana, Brazil; at least 130 individuals in Balbina Lake, Brazil; 54 individuals in Araguaia, above Bananal Island; 32 individuals in Yasuni National Park, Ecuador; and at least 35 individuals in Rewa Head, Guyana. Estimates have been provided for the following countries: 60 animals in Bolivia in the northwest in the Madre de Dios-Beni sub-basin; 50 individuals in 118,031 km² of the Pantanal (Paraguay river sub-basin), and 600 animals in the 186,460 km² of the northeast (Itenez sub-basin), totaling an estimated 700 individuals; less than 250 animals in Ecuador; at least 200 animals in French Guiana; and 24-32 animals in Paraguay. Overall, currently, Giant otters are classified as Endangered (EN) and their numbers today are decreasing.

Fun Facts for Kids

  • The Giant otter was discovered by Gmelin in 1788. It is also known as the Guiana flat-tailed otter, margin-tailed otter, and winged-tailed otter.
  • These animals are most active from 10-11 am and from 3-5 pm. They take a nap at mid-day during really warm weather.
  • Giant otters are able to swim 330 feet (100 meters) in less than 30 seconds.
  • Because of their size and speed of swimming, Giant otters are successful in competing for fish with Black caimans and jaguars.
  • Giant otters do not store food. They will seek a peaceful place (or "picnic spot") to eat their prey.
  • Giant otters can hunt singly, in pairs, and in groups, relying on sharp eyesight to locate prey. They prefer prey fish that are generally immobile on river bottoms in clear water. They chase prey rapidly and tumultuously, with lunges and twists through the shallows and few missed targets.

Coloring Pages

References

1. Giant Otter Wikipedia article - https://en.wikipedia.org/wiki/Giant_otter
2. Giant Otter on The IUCN Red List site - http://www.iucnredlist.org/details/18711/0

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