# Giant otter (*Pteronura brasiliensis*)

Giant otters are playful animals that live in rivers, lakes and swamps in South America. They are known for their loud calls and love to swim together as a family.

- **Category:** [Mammals](https://www.snappit.app/explore/categories/mammal)
- **Rarity:** Common
- **Danger:** 2/5 · Low
- **Habitat:** Wetlands

![Giant otter](https://commons.wikimedia.org/w/index.php?title=Special:Redirect/file/Giantotter.jpg&width=800)

Photo: CC BY-SA 2.5 · [Wikimedia Commons](https://commons.wikimedia.org/wiki/File:Giantotter.jpg)

## Appearance

The giant otter has sleek dark brown fur with a unique creamy or white patch on its throat, which is different for every individual. It also has a long, powerful, flattened tail and fully webbed feet, giving it a distinctive appearance.

## Taxonomy

- **Kingdom:** Animalia
- **Phylum:** Chordata
- **Class:** Mammalia
- **Order:** Carnivora
- **Family:** Mustelidae
- **Genus:** Pteronura

## Giant otter, up close

The giant otter (Pteronura brasiliensis) is the longest otter in the world, reaching 1.5–1.8 m including its flat, paddle-like tail. It lives in noisy family groups in the rivers, lakes and swamps of tropical South America, is active by day and eats mainly fish. Hunted for its fur until the 1970s, it is now Endangered because of habitat loss, mercury pollution from gold mining and conflict with fishers.

Also called: River wolf, Giant river otter, Giant Brazilian otter, Lobo de río (Spanish), Ariranha (Portuguese), Perro de agua (Spanish).

The “river wolf” of South America: an otter as long as a grown-up is tall, living in noisy families where everyone has its own throat print. Spin it, tap it, then test yourself.

### Special abilities

- **Throat-Print ID** (294 otters identified in one park): Every giant otter has its own pattern of cream marks on the throat and chest. Scientists use it like a fingerprint to follow each otter through its life. [3][1][11][15]
  - The marks are there from birth and range from a tiny spot under the chin to a big bib across the chest.
  - Over 16 years in Manu National Park, Peru, researchers identified 294 otters this way, including 177 cubs. Only 3 had no mark.
  - Curious otters often swim towards boats and stretch up out of the water, so researchers can film each throat and check it against a catalogue.
- **22-Sound Chat** (22 call types in adults): One of the noisiest otters. A study of wild and zoo families sorted adult calls into 22 types, from soft contact hums to loud screams. [6][16][1]
  - Hums keep the family together while they swim and travel; snorts and “hah” calls warn of danger; youngsters scream when they beg for fish.
  - Newborn cubs babble: researchers heard 11 different call types in their babbling.
  - A study in Brazil’s Pantanal counted 15 sound types. The total depends on how scientists split up similar calls.
  - Giant otter call types found by each study: Adults (Mumm & Knörnschild 2014) 22; Adults, Pantanal (Leuchtenberger et al. 2014) 15; Babbling newborn cubs 11; First study, Suriname (Duplaix 1980) 9
- **Winged Tail** (45–65 cm flat, paddle-like tail): Pteronura means “winged tail”. The thick, flattened tail is the giant otter’s high-speed paddle. [11][17][1]
  - Swimming slowly, it paddles with all four webbed feet. For speed, it holds its feet still and waves its tail instead.
  - The tail can be nearly half as long as the head and body.
  - All five toes on each foot have thick webbing.
  - Total length (1.45–1.8 m): Tail: 45–65 cm
- **Periscope** (20–30 m closest people should get): To check out something new, a giant otter stands up in the water and stretches its head and neck high, often snorting a warning. [3][6][1]
  - Most families in Manu reacted to researchers’ canoes by swimming closer and periscoping again and again.
  - Periscoping shows off the throat patch, which helps scientists recognise each otter.
  - Experts advise never getting closer than 20–30 m and never chasing a family. Otters that have been hunted flee from people even 100 m away.
- **Family Patrol** (2 of 2 family stand-offs that sent a jaguar away): A family is a match for big predators. Groups have been seen mobbing a jaguar on the riverbank until it left. [18][19][7][15]
  - Jaguars do sometimes catch giant otters. The first confirmed case, in 2015, was a lone otter resting on the bank, not a family.
  - When predators or strange otters appear, the whole family screams together. Each family’s chorus sounds slightly different.
  - Families also defend their stretch of river against other otter groups with scent marks and loud calls.
- **Smell Signposts** (62% of marks made by the breeding male): Families keep shared toilets, called latrines, on the riverbank. The smell tells other otters that this stretch of river is taken. [10][1][20][15]
  - They trample droppings, urine and smelly mucus into campsites, logs and rocks.
  - In a Pantanal study, families spent 4.3–44.7 minutes scent-marking. The breeding male made 62% of the marks and often marked over the others’.
  - Latrines smell so strong that researchers find them easily, and collect droppings there to learn what otters eat.
- **Fish Furnace** (3–4 kg of fish a day): An adult eats about 3–4 kg of fish a day, and a meal passes through its body in about 3 hours. [3][1][5][21][20]
  - In zoos, adults eat about 10% of their body weight every day. A sea otter needs about 25%.
  - Favourite prey include trahiras, cichlids, characins and catfish, mostly 7–30 cm long and caught near the bank.
  - Cubs live almost only on milk until about 3 months, when their parents start bringing them small fish to practise on.
  - Food eaten each day: Giant otter (zoo adults) ≈10%; Sea otter ≈25%
- **Team Fishing** (8 vs 5 bigger groups catch more fish; still debated): Do giant otters hunt as a team? Families fish side by side, but scientists still argue about how much they really work together. [3][1][6][22]
  - Groups of about 8 spent less time getting food and caught fish faster than groups of about 5.
  - Yet each otter usually catches and eats its own fish. True cooperative fishing seems uncommon, though not absent.
  - In a zoo test, pairs of giant otters pulled the two ends of a rope together to get food, but struggled when the timing got harder.

### Body parts

- **Throat patch** (3 of 294 otters had no mark) [1][2][3]
  - Cream or white marks on the lips, chin, throat and chest. Every otter’s pattern is different.
  - It can be a tiny spot under the chin or a big bib across the chest, and it is there from birth.
  - In Manu National Park, Peru, only 3 of the 294 otters studied had no throat mark at all.
- **Eyes** [1][4][5]
  - Giant otters hunt mainly by sight, so they prefer clear-water and black-water rivers, lakes and creeks.
  - They are active by day, which makes them one of the easier South American carnivores to watch.
  - Cubs are born with their eyes closed. In zoos the eyes open at about 4–6 weeks.
- **Ears** (22 adult call types to hear) [1][6][7]
  - Very small, round and furry.
  - They pick up a big vocabulary: scientists have described 22 call types in adults.
  - Each family’s group chorus sounds a little different, so neighbours may be able to tell who is calling.
- **Whiskers** [1][8]
  - Stiff whiskers circle the muzzle, with more above the eyes and on the sides of the lower lips.
  - In Eurasian otters, the whisker nerves have about 4 times as many fibres as a polecat’s, a sign that whiskers matter in water.
  - Nobody has yet tested what giant otters feel with theirs. They seem to rely mostly on their eyes when hunting.
- **Nose** [1][9][10]
  - Even the nose pad is covered in short fur.
  - Their DNA shows that many smell-receptor genes have stopped working, as in other water mammals.
  - Smell still matters: families leave scent messages at shared latrines along the bank.
- **Teeth** (3–4 kg of fish a day) [5][3][1]
  - Zoo cubs only a few days old already had their canine teeth.
  - Most prey fish are 7–30 cm long, but giant otters have been seen catching fish up to about 100 cm.
  - At about 3 months, cubs start grabbing fish with their mouth and front paws.
- **Paws** (4 km+ walked overland to a lake) [1][10]
  - All five toes on each foot are joined by thick webbing.
  - On land a giant otter can travel 4 km or more to reach a lake, and climb almost vertical banks 4 m high.
  - Families trample and rub scent into the ground with their paws when they mark their territory.
- **Tail** (45–65 cm long) [2][11][1]
  - Thick at the base and strongly flattened towards the tip, like a paddle.
  - It gives the giant otter its scientific name: Pteronura means “winged tail”.
  - The tail can be nearly half as long as the head and body.
- **Coat** [2][1][12][13]
  - Very short, smooth, dark brown fur that looks chocolate-coloured when wet.
  - In the late 1960s one giant otter skin sold for about US$440, more than twice the price of a neotropical otter’s.
  - An estimated 386,000 giant otters were killed for their skins in the central-western Brazilian Amazon between 1904 and 1969.
- **Gut** (≈3 h from meal to latrine) [1][5][14]
  - Food passes through in about 3 hours, a sign of a fast metabolism.
  - In zoos, adults eat about 10% of their body weight in fish every day.
  - Mercury builds up in fish-eaters at the top of the food chain: Pantanal otters had 7.15 µg/g in their fur on average.

### Stats

| Stat | Value | Notes |
|---|---|---|
| Length | 1.5–1.8 m | from nose to tail tip; About as long as a grown-up is tall [3][1][24] |
| Weight | 20–35 kg | males 23–32 kg and females 20–29 kg in one review; Longer than a sea otter, but lighter [3][11][2][21] |
| Tail | 45–65 cm | flat and paddle-like; ≈ a third of its total length [11] |
| Family | 2–16 | otters per group; 6 on average in Manu, Peru; Groups of up to 20 have been reported [3][15] |
| Food | 3–4 kg | of fish a day for an adult; ≈ 10% of its body weight [3][1][5] |
| Digestion | ≈3 h | for a meal to pass through [1][5] |
| Calls | 22 | adult call types, plus 11 in babbling cubs [6] |
| Litter | 1–5 | cubs per litter seen in the wild, most often 2 [3] |
| Newborn | 150–265 g | in zoos; born furred with eyes closed; Grows to 20–35 kg [5][1] |
| Oldest | 15.5 yrs | in the wild (Manu, Peru); 20 years in a zoo [3][1] |

### Photos

- [Periscoping in the Pantanal: note the cream throat print](https://commons.wikimedia.org/wiki/File:Giant_otter_(Pteronura_brasiliensis)_2.jpg) (photo: Charles J. Sharp, CC BY-SA 4.0)
- [A juvenile on the Cuiabá River, Pantanal](https://commons.wikimedia.org/wiki/File:Giant_otter_(Pteronura_brasiliensis)_juvenile.jpg) (photo: Charles J. Sharp, CC BY-SA 4.0)
- [Lunch time: an adult eats 3–4 kg of fish a day](https://commons.wikimedia.org/wiki/File:018_Giant_otter_eating_a_fish_in_Encontro_das_%C3%81guas_State_Park_Photo_by_Giles_Laurent.jpg) (photo: Giles Laurent, CC BY-SA 4.0)
- [Family members resting on a log in the Pantanal](https://commons.wikimedia.org/wiki/File:Giant_otters_(Pteronura_brasiliensis).jpg) (photo: Charles J. Sharp, CC BY-SA 4.0)
- [Swimming in Encontro das Águas State Park, Brazil](https://commons.wikimedia.org/wiki/File:139_Giant_otter_swimming_in_Encontro_das_%C3%81guas_State_Park_Photo_by_Giles_Laurent.jpg) (photo: Giles Laurent, CC BY-SA 4.0)
- [A family heads ashore in Cantão State Park, Brazil](https://commons.wikimedia.org/wiki/File:Four_Giant_Otters.JPG) (photo: Araguaia.org (Rio Cicica), CC BY 3.0)
- [A noisy giant otter calls as it swims towards a boat](https://commons.wikimedia.org/wiki/File:Giant_Otter_(8016054171)_(2).jpg) (photo: Alastair Rae, CC BY-SA 2.0)
- [A family group on the Cuiabá River, Pantanal](https://commons.wikimedia.org/wiki/File:Giant_Otters_(Pteronura_brasiliensis)_family_group_..._(48426471236).jpg) (photo: Bernard Dupont, CC BY-SA 2.0)
- [A young giant otter](https://commons.wikimedia.org/wiki/File:Infant_giant_otter_sitting_on_rock_-_DPLA_-_ec6484efbd3d00a6e51690181265a93a.jpg) (photo: Warren Garst, CC BY-SA 4.0)
- [A giant otter family stands up to a jaguar in the Pantanal](https://commons.wikimedia.org/wiki/File:1_Jaguar_fighting_with_giant_otters%2C_Parque_Estadual_Encontro_das_%C3%81guas_Thomas-Fuhrmann.jpg) (photo: Thomas Fuhrmann, CC BY-SA 4.0)

### Questions

- **How big is a giant otter?** Adults measure 1.5–1.8 m from nose to tail tip, about as long as a grown-up is tall, and weigh about 20–35 kg. The tail alone is 45–65 cm. Males and females are almost the same size. [3][11][24][2]
- **Is the giant otter the biggest otter?** It is the longest otter and the longest member of the weasel family. But the sea otter is heavier: big males weigh 36–45 kg or more, while giant otters weigh about 20–35 kg. [29][3][21]
- **Why is the giant otter called the river wolf?** Lobo de río (“river wolf”) is one of its Spanish names. Like a wolf pack, a giant otter family lives, travels and defends its territory together, and scientists compare its breeding system with that of African wild dogs. [46][11][3]
- **What do giant otters eat?** Mostly fish such as trahiras, cichlids, characins and catfish: fish turned up in every dropping in two diet studies. An adult eats about 3–4 kg a day. Now and then they also take crabs, snakes, turtles and young caimans. [20][27][1][3][28]
- **Are giant otters dangerous to people?** They are wild predators with strong teeth, and families defend their cubs and territory. Watch them only from a boat or a viewing tower, stay at least 20–30 m away, and never chase, feed or try to touch them. If you see one up close, tell an adult. [1][3]
- **Why are giant otters endangered?** Hunting for their skins wiped them out from large areas until the 1970s. Today the main threats are habitat loss, dams, mercury pollution from gold mining, fires and droughts, diseases from dogs and conflict with fishers. Families have few cubs, so numbers recover slowly. [13][1][14][34][36][25][3]
- **How many giant otters are left?** Nobody knows the world total. Surveys suggest about 4,700 in Brazil (about 3,950 of them in the Pantanal) and about 1,000 in Bolivia, with far fewer elsewhere. The species is gone from Uruguay and probably Argentina, where zoo-bred otters are now being released. [2]
- **How do scientists tell giant otters apart?** By the cream marks on their throats. Each pattern is different and present from birth, so researchers film otters as they periscope and match each throat to a catalogue, sometimes for the otter’s whole life. [3][1]

### Giant otter myths and facts

Tap Myth or Fact for each claim, then check the answer.

- "The giant otter is the biggest otter, so it must be the heaviest too." **Myth!** It is the longest, at up to about 1.8 m. But a big male sea otter weighs 36–45 kg or more, while giant otters weigh about 20–35 kg. [3][21][11]
- "You can tell giant otters apart by the cream marks on their throats." **Fact!** Each pattern is different and is there from birth. Researchers in Peru identified 294 otters this way; only 3 had no mark. [3][1]
- "Giant otters hunt as a team, like a wolf pack." **Not proven!** Families fish side by side and bigger groups catch more, but each otter usually catches and eats its own fish. Real teamwork seems uncommon and is still debated. [3][1][6]
- "Giant otters can grow to 2.4 m long." **Myth!** Old books gave 1.5–2.4 m, partly based on dried skins, which stretch. Measured adults are 1.5–1.8 m including the tail. [1]
- "Every grown-up in a giant otter family has cubs." **Myth!** Only the dominant pair breeds. Older brothers and sisters help feed, babysit and teach the cubs. [3][23]
- "Nothing hunts a giant otter." **Myth!** Jaguars occasionally catch one: the first confirmed case, in 2015, was a lone otter resting on the bank. Families have been seen mobbing jaguars until they left. [19][18]
- "Giant otters empty rivers of the fish people need." **Myth!** In one Amazon reserve, otters and people ate mostly different fish, and otters near nets did not reduce the catch. In Colombia, researchers also found that otters interfere little with fishing. [25][26]
- "Giant otters only eat fish." **Myth!** Fish turned up in every dropping in two diet studies, but giant otters also eat crabs, small anacondas, turtles and young caimans now and then. [20][27][1][28]

### Giant otter records

Superlatives and record holders, each checked against its source.

- Longest otter: Giant otter, 1.5–1.8 m (the longest member of the weasel family, tail included) [29][3][11]
- Heaviest otter: Sea otter (big males), 36–45 kg+ (shorter than a giant otter, but heavier) [21]
- Biggest otter vocabulary: Giant otter, 22 call types (the most vocal and most social otter studied so far) [6]
- Only otter with helpers: Giant otter, 1 of 13 species (the only otter known to breed cooperatively, with older offspring helping to raise the cubs) [23][3]
- Oldest wild giant otters: A male and a female in Manu, Peru, 15.5 and 13.5+ yrs (their ages when last seen: the oldest recorded in the wild) [3]
- Oldest in a zoo: A male at Brazil’s National Institute of Amazonian Research, 20 yrs (another male at Dortmund Zoo, Germany, lived to 19 years 8 months) [1]
- Most cubs from one pair: A breeding pair in Manu, Peru, 25 cubs (raised to at least 6 months old while they led their family) [3]
- Biggest known stronghold: Brazilian Pantanal, ≈3,950 otters (estimated along 7,350 km of rivers) [2]

### Life of a giant otter cub

From a furry newborn in a riverbank den to a parent with its own territory.

- **Day 1**: Born in a den. After a pregnancy of 64–77 days, cubs are born in a den dug into the bank. They have fur and closed eyes and, in zoos, weigh 150–265 g. [3][1][5]
- **≈2 weeks**: First dip. Wild parents carry cubs out of the den in their mouths and dip them in the water at the entrance, even before their eyes open. [5]
- **4–6 weeks**: Eyes open. In zoos the eyes open at 4–6 weeks. In the wild, cubs are following their parents out of the den by about 6 weeks. [5]
- **≈2 months**: Out with the family. Cubs leave the den behind and start joining the family on fishing trips. [3][6]
- **≈3 months**: First fish. Until now cubs live almost only on milk. Parents bring them small fish to grab with their mouth and front paws. [5]
- **6–10 months**: Growing up. Cubs are weaned at about 6 months. By about 10 months they hunt as well as their parents and look like adults. [3][5]
- **≈1.5 years**: Family helper. Young otters still get fish from the family until about 1.5 years old, and help look after the next litters. [3][23]
- **2.5–3 years**: Leaving home. On average, females leave at about 2.5 years and males at about 3, to find a mate and a territory of their own. [3]
- **3–5 years**: First cubs. The youngest parents recorded were 3 years old. On average, females had their first litter at about 4.4 years. [3]
- **15+ years**: A long life. The oldest wild giant otters known were 15.5 (a male) and at least 13.5 (a female). In zoos they have lived to 20. [3][1]

### Giant otter family life

Dens, campsites and smelly latrines: how a giant otter family shares its stretch of river.

- **2–16** otters in a family. A breeding pair and their young from several years. Groups of up to 20 have been reported; in Manu the average was 6. [3][15]
- **1 pair** has the cubs. Only the dominant female and male breed. Older brothers and sisters babysit, share food and teach the cubs to fish. [3][23]
- **182 dens** and 193 campsites in one reserve. Families dig dens into the bank and clear campsites to rest and groom, almost always less than 2 m from the water. [30][1]
- **62%** of scent marks by the breeding male. Families trample droppings, urine and scent into shared latrines. Groups spent 4.3–44.7 minutes marking during a Pantanal study. [10]
- **4–59×** bigger home range in the wet season. When the rivers flood, families follow the fish into flooded forest, grassland and swamps, leaving their usual campsites and dens for a while. [31][4]
- **11 of 43** begs answered. When an old breeding female named Cacao could no longer catch big fish, her grown-up young shared food with her: she begged 43 times and was given food 11 times. [23]

### Are giant otters endangered?

Yes. Giant otters bounced back in some protected rivers after the fur trade ended, but new threats now crowd the riverbanks they depend on.

- **IUCN Red List:** Endangered (EN) (Population decreasing). Gone from Uruguay and probably Argentina, and patchy across much of its range. Experts think numbers fell by more than half over the last 25 years (about three otter generations) and could halve again in the next 25 if current trends continue. [32][2][33]
- IUCN Red List, 2023 assessment (Groenendijk et al.).
- **Threat: The fur trade (past)** (≈386,000): An estimated 386,000 giant otters were killed for their skins in the central-western Brazilian Amazon in 1904–1969, and Peru officially exported at least 23,162 pelts from the mid-1940s to 1973. Noisy, curious families active by day were easy targets. [13][3][1]
- **Threat: Gold mining and mercury** (7.15 µg/g): Mercury used to mine gold builds up in fish and then in otters. Pantanal otters averaged 7.15 µg/g of mercury in their fur, above the 1–5 µg/g of otters living away from pollution, even about 475 km from mining. [14][3][1]
- **Threat: Lost and burned habitat**: Dams, deforestation, roads and settlements crowd the riverbanks otters need. After fires burned 3.9 million ha of the Pantanal in 2020, giant otters showed the steepest drop of 35 species in one camera study. [1][2][34]
- **Threat: Conflict with fishers**: Some fishers blame otters for empty nets and kill them. Studies in Brazil and Colombia found that otters and people mostly take different fish. [26][25][35]
- **Threat: Diseases from dogs** (5 of 10): Five of 10 wild giant otters tested in Brazil had antibodies to canine distemper virus, a disease spread by dogs. [36][1]
- **Threat: Pushy tourism**: In three lakes heavily visited by tourists, families raised about a third fewer young than expected. Mothers with small cubs are especially sensitive. [1]
- **Helping: Hunting bans and CITES** (0 → 41): Peru banned commercial hunting in 1973, and from 1975 the CITES treaty stopped the international skin trade. On Peru’s Yavarí-Mirín and Yavarí rivers, surveys found no otters in 1992–93 but 41 in 2003–04. [3][13][37]
- **Helping: Protected lakes and calm tourism** (7 → 12): In Manu National Park, the number of family groups grew from 7 to 12 between 1991 and 2005. Viewing towers, boat limits and minimum distances let otters and visitors share lakes. [3][1]
- **Helping: Back to Argentina**: Two pairs of zoo-bred giant otters were released in Argentina’s Iberá wetlands between 2019 and 2022, where the species was thought to be extinct. Zoos on four continents now breed giant otters together. [2][38]
- **Helping: New global protection** (2026): In 2026 the Convention on Migratory Species added the giant otter to both of its appendices, from 27 June 2026, to help countries protect it across borders. [39][2]
- **Sea otter** (EN): Heavier than the giant otter, with the densest fur of any mammal: 500,000 hairs per cm². The fur trade nearly wiped it out too. [40][41]
- **Eurasian otter** (NT): A smaller, mostly solitary otter that has made a comeback in the British Isles since the 1980s. [42][43]
- **Neotropical otter** (NT): Shares many rivers with the giant otter. In the 1950s–1970s, more than 30,000 were killed for their skins every year. [44][45]

### Giant otter vs sea otter vs Eurasian otter

Three very different otters: the longest, the heaviest and one of the most widespread.

| | Giant otter | Sea otter | Eurasian otter |
|---|---|---|---|
| Scientific name [11][40][42] | Pteronura brasiliensis | Enhydra lutris | Lutra lutra |
| Lives in [1][40][42] | Rivers, lakes and swamps of tropical South America | North Pacific coasts, such as Alaska | Fresh water and coasts from Ireland to China and South-East Asia |
| Total length [3][21][42] | 1.5–1.8 m | up to ≈1.5 m | 1.0–1.4 m |
| Weight [3][11][21][42] | 20–35 kg | males 36–45 kg or more; females 23–32 kg | 4–11 kg |
| Tail [11][40][42] | 45–65 cm, flat like a paddle | 12–33 cm | 35–40 cm |
| Social life [3][40][42] | Family groups of 2–16 | Groups of males or of females | Mostly alone; mothers with young |
| Main food [1][40][42] | Fish | Clams, crabs and sea urchins | Fish, crustaceans and amphibians |
| IUCN status [32][41][43] | Endangered | Endangered | Near Threatened |

The giant otter is the longest otter; big male sea otters are the heaviest.

### Giant otter calls and signals

- Periscoping: Standing up in the water with head and neck stretched high, to check out something new, like a boat. [3]
- Snort: An alarm or warning call. [6]
- “Hah” call: Another alarm call, used when an otter feels threatened. [6]
- Soft hum: Keeping in touch while swimming, travelling or resting together. [6]
- Wavering scream: Alarm, or an otter that has lost its family calling for them. [6][23]
- Begging scream: A cub or juvenile asking an older otter for fish. [6]
- Group chorus: The whole family screams together at predators or intruders. Each family’s chorus sounds different. [7]
- Daisy-chain grooming: Several otters in a row grooming each other after a meal: relaxed family time. [1]
- Panic porpoising: Otters that have been hunted flee from people 100 m or more away, leaping in and out of the water. [1]

### Family

- **Adult**: Dark chocolate fur with a big cream throat patch that runs down the chest in two long streaks. (1.5–1.8 m and 20–35 kg · one of the breeding pair) [1][3]
- **Mate**: Same size and colour, but only a few small cream spots under the chin: that is how you tell the pair apart. (Males and females look much alike · the breeding male does most of the scent-marking) [1][3][10]
- **Juvenile**: Smaller and a little paler than the adults, with a blotchy cream bib it has had since birth. (6 months to 1.5 years old · still fed by the family) [2][3]
- **Adult with cub**: An adult carrying a small cub in its mouth. Cubs are born furred, with closed eyes and their throat marks already showing. (Cubs leave the den at about 2 months) [1][5][3]

### Giant otter quiz

1. What makes each giant otter look different from the others? **The cream marks on its throat.** Each otter’s throat and chest marks form a unique pattern that is there from birth. [3][1]
2. What does the name Pteronura mean? **Winged tail.** It refers to the flat, wing-like tail. [11]
3. How long can a giant otter grow, including its tail? **About 1.8 m.** Adults measure 1.5–1.8 m, about as long as a grown-up is tall. [3][24]
4. Which otter is the heaviest? **Sea otter.** A big male sea otter weighs 36–45 kg or more. Giant otters are longer but lighter. [21][3]
5. How many adult call types did one study find? **22.** 22 types in adults, plus 11 in babbling cubs. [6]
6. About how much fish does an adult giant otter eat in a day? **3–4 kg.** About 3–4 kg, roughly a tenth of its body weight. [3][1]
7. Who has the cubs in a giant otter family? **Only the dominant pair.** The rest of the family helps babysit, feed and teach the cubs. [3]
8. What is “periscoping”? **Standing up in the water to look around.** The otter stretches its head and neck high out of the water to check out something new. [3]
9. What did giant otter families do when they met a jaguar? **Mobbed it until it left.** In both encounters involving a family, the otters mobbed the jaguar until it left. [18]
10. What is a giant otter latrine? **A shared toilet that works as a smell signpost.** Families mark their territory with droppings and scent at shared latrines on the bank. [15][10]
11. About how old are cubs when they start going out with the family? **2 months.** Cubs leave the den at about 2 months and start joining fishing trips. [3][6]
12. Which modern threat comes from gold mining? **Mercury pollution.** Mercury used to mine gold builds up in fish and then in the otters that eat them. [14][1]

### Sources (checked 2026-10-16)

1. [Duplaix N, Evangelista E, Rosas FCW (2015). Advances in the study of giant otter (Pteronura brasiliensis): ecology, behavior, and conservation: a review. Latin American Journal of Aquatic Mammals 10(2): 75–98.](https://doi.org/10.5597/lajam00200)
2. [Convention on Migratory Species (2025). Proposal for the inclusion of the giant otter (Pteronura brasiliensis) on Appendix I and II of the Convention. UNEP/CMS/COP15/Doc.30.2.3 (proponent: France).](https://www.cms.int/sites/default/files/document/2025-11/cms_cop15_doc.30.2.3_listing-proposal-giant-otter_e.pdf)
3. [Groenendijk J, Hajek F, Johnson PJ, Macdonald DW, Calvimontes J, Staib E, Schenck C (2014). Demography of the giant otter (Pteronura brasiliensis) in Manu National Park, south-eastern Peru: implications for conservation. PLoS ONE 9(8): e106202.](https://doi.org/10.1371/journal.pone.0106202)
4. [Duplaix N (1980). Observations on the ecology and behavior of the giant river otter Pteronura brasiliensis in Suriname. Revue d'Écologie (La Terre et la Vie) 34(4): 495–620.](https://doi.org/10.3406/revec.1980.4073)
5. [Sykes-Gatz S (2005). International Giant Otter Studbook Husbandry and Management Information and Guidelines, 2nd edition. Zoologischer Garten Dortmund (hosted by the IUCN SSC Otter Specialist Group).](https://www.otterspecialistgroup.org/wp-content/uploads/2025/09/International_Giant_Otter_Studbook_Husbandry_and_Management_Information_and_Guidelines_2005.pdf)
6. [Mumm CAS, Knörnschild M (2014). The vocal repertoire of adult and neonate giant otters (Pteronura brasiliensis). PLoS ONE 9(11): e112562.](https://doi.org/10.1371/journal.pone.0112562)
7. [Mumm CAS, Knörnschild M (2017). Territorial choruses of giant otter groups (Pteronura brasiliensis) encode information on group identity. PLoS ONE 12(10): e0185733.](https://doi.org/10.1371/journal.pone.0185733)
8. [Hyvärinen H, Palviainen A, Strandberg U, Holopainen IJ (2009). Aquatic environment and differentiation of vibrissae: comparison of sinus hair systems of ringed seal, otter and pole cat. Brain, Behavior and Evolution 74(4): 268–279.](https://doi.org/10.1159/000264662)
9. [Beichman AC, Koepfli KP, Li G, Murphy W, Dobrynin P, Kliver S, et al. (2019). Aquatic adaptation and depleted diversity: a deep dive into the genomes of the sea otter and giant otter. Molecular Biology and Evolution 36(12): 2631–2655.](https://doi.org/10.1093/molbev/msz101)
10. [Leuchtenberger C, Mourão G (2009). Scent-marking of giant otter in the southern Pantanal, Brazil. Ethology 115(3): 210–216.](https://doi.org/10.1111/j.1439-0310.2008.01607.x)
11. [IUCN SSC Otter Specialist Group. Giant otter (Pteronura brasiliensis): species page.](https://www.otterspecialistgroup.org/otter-species/giant-otter-pteronura-brasiliensis/)
12. [Pimenta NC, Antunes AP, Barnett AA, Macedo VW, Shepard GH (2018). Differential resilience of Amazonian otters along the Rio Negro in the aftermath of the 20th century international fur trade. PLoS ONE 13(3): e0193984.](https://doi.org/10.1371/journal.pone.0193984)
13. [Antunes AP, Fewster RM, Venticinque EM, Peres CA, Levi T, Rohe F, Shepard GH (2016). Empty forest or empty rivers? A century of commercial hunting in Amazonia. Science Advances 2(10): e1600936.](https://doi.org/10.1126/sciadv.1600936)
14. [Soresini G, Aguiar da Silva F, Leuchtenberger C, Mourão G (2021). Total mercury concentration in the fur of free-ranging giant otters in a large Neotropical floodplain. Environmental Research 198: 110483.](https://doi.org/10.1016/j.envres.2020.110483)
15. [Leuchtenberger C, Magnusson WE, Mourão G (2015). Territoriality of giant otter groups in an area with seasonal flooding. PLoS ONE 10(5): e0126073.](https://doi.org/10.1371/journal.pone.0126073)
16. [Leuchtenberger C, Sousa-Lima R, Duplaix N, Magnusson WE, Mourão G (2014). Vocal repertoire of the social giant otter. Journal of the Acoustical Society of America 136(5): 2861–2875.](https://doi.org/10.1121/1.4896518)
17. [Bender J (2001). Pteronura brasiliensis (giant otter). Animal Diversity Web, University of Michigan Museum of Zoology.](https://animaldiversity.org/accounts/Pteronura_brasiliensis/)
18. [Leuchtenberger C, Almeida SB, Andriolo A, Crawshaw PG (2016). Jaguar mobbing by giant otter groups. acta ethologica 19(2): 143–146.](https://doi.org/10.1007/s10211-016-0233-4)
19. [Ramalheira CS, Bozzetti BF, da Cruz AD, Palmeirim AF, Cabral MMM, Rosas FCW (2015). First record of jaguar predation on giant otter (Pteronura brasiliensis). Animal Biology 65(1): 81–86.](https://doi.org/10.1163/15707563-00002461)
20. [Rosas FCW, Zuanon JAS, Carter SK (1999). Feeding ecology of the giant otter, Pteronura brasiliensis. Biotropica 31(3): 502–506.](https://doi.org/10.1111/j.1744-7429.1999.tb00393.x)
21. [Alaska Department of Fish and Game. Sea otter (Enhydra lutris) species profile.](https://www.adfg.alaska.gov/index.cfm?adfg=seaotter.main)
22. [Schmelz M, Duguid S, Bohn M, Völter CJ (2017). Cooperative problem solving in giant otters (Pteronura brasiliensis) and Asian small-clawed otters (Aonyx cinerea). Animal Cognition 20(6): 1107–1114.](https://doi.org/10.1007/s10071-017-1126-2)
23. [Davenport LC (2010). Aid to a declining matriarch in the giant otter (Pteronura brasiliensis). PLoS ONE 5(6): e11385.](https://doi.org/10.1371/journal.pone.0011385)
24. [CDC National Center for Health Statistics. FastStats: Body measurements (measured average height of US adults aged 20+).](https://www.cdc.gov/nchs/fastats/body-measurements.htm)
25. [Rosas-Ribeiro PF, Rosas FCW, Zuanon J (2012). Conflict between fishermen and giant otters Pteronura brasiliensis in Western Brazilian Amazon. Biotropica 44(3): 437–444.](https://doi.org/10.1111/j.1744-7429.2011.00828.x)
26. [Trujillo F, Caro A, Martínez S, Rodríguez-Maldonado MV (2015). Negative interactions between giant otters (Pteronura brasiliensis) and local fisheries in the Amazon and Orinoco basins in Colombia. Latin American Journal of Aquatic Mammals 10(2): 122–130.](https://doi.org/10.5597/lajam00204)
27. [Cabral MMM, Zuanon J, de Mattos GE, Rosas FCW (2010). Feeding habits of giant otters Pteronura brasiliensis (Carnivora: Mustelidae) in the Balbina hydroelectric reservoir, Central Brazilian Amazon. Zoologia (Curitiba) 27(1): 47–53.](https://doi.org/10.1590/S1984-46702010000100008)
28. [Ribas C, Damasceno G, Magnusson W, Leuchtenberger C, Mourão G (2012). Giant otters feeding on caiman: evidence for an expanded trophic niche of recovering populations. Studies on Neotropical Fauna and Environment 47(1): 19–23.](https://doi.org/10.1080/01650521.2012.662795)
29. [Carter SK, Rosas FCW (1997). Biology and conservation of the giant otter Pteronura brasiliensis. Mammal Review 27(1): 1–26.](https://doi.org/10.1111/j.1365-2907.1997.tb00370.x)
30. [Lima DS, Marmontel M, Bernard E (2012). Site and refuge use by giant river otters (Pteronura brasiliensis) in the Western Brazilian Amazonia. Journal of Natural History 46(11–12): 729–739.](https://doi.org/10.1080/00222933.2011.654280)
31. [Leuchtenberger C, Oliveira-Santos LGR, Magnusson W, Mourão G (2013). Space use by giant otter groups in the Brazilian Pantanal. Journal of Mammalogy 94(2): 320–330.](https://doi.org/10.1644/12-MAMM-A-210.1)
32. [Groenendijk J, Leuchtenberger C, Marmontel M, Van Damme PA, Wallace R, Schenck C (2023). Pteronura brasiliensis. The IUCN Red List of Threatened Species 2023: e.T18711A244867206.](https://doi.org/10.2305/IUCN.UK.2023-1.RLTS.T18711A244867206.en)
33. [Grattarola F, Tschernosterová K, Keil P (2024). A continental-wide decline of occupancy and diversity in five Neotropical carnivores. Global Ecology and Conservation 55: e03226.](https://doi.org/10.1016/j.gecco.2024.e03226)
34. [Loureiro NG, Viana DFP, Noble CD, Porfírio GEO, Moreno WHA, Queiroz MAC, Tonolli GV, Peres CA, Fernandes-Ferreira H (2026). Living in the Pyrocene: assemblage-wide terrestrial vertebrate responses to mega-fires in the Pantanal wetlands. Ecology and Evolution 16(8): e74130.](https://doi.org/10.1002/ece3.74130)
35. [Lima DS, Marmontel M, Bernard E (2014). Conflicts between humans and giant otters (Pteronura brasiliensis) in Amanã Reserve, Brazilian Amazonia. Ambiente & Sociedade 17(2): 127–142.](https://doi.org/10.1590/S1414-753X2014000200009)
36. [Furtado MM, Soresini G, Jácomo ATA, Metzger B, Rosas FCW, Ramalheira CS, et al. (2026). Pathogen surveillance in free-ranging giant otters (Pteronura brasiliensis) in three ecoregions of Brazil. Journal of Wildlife Diseases 62(3): 666–674.](https://doi.org/10.7589/JWD-D-25-00104)
37. [Recharte Uscamaita M, Bodmer R (2010). Recovery of the Endangered giant otter Pteronura brasiliensis on the Yavarí-Mirín and Yavarí Rivers: a success story for CITES. Oryx 44(1): 83–88.](https://doi.org/10.1017/S0030605309990196)
38. [Schikora TF (2020). Giant otter Pteronura brasiliensis breeding programmes: challenges and current developments. International Zoo Yearbook 54(1): 72–79.](https://doi.org/10.1111/izy.12270)
39. [Convention on Migratory Species (2026). Appendices I and II of the Convention on the Conservation of Migratory Species of Wild Animals, as amended by the Conference of the Parties in 2026; effective 27 June 2026.](https://www.cms.int/sites/default/files/basic_page_documents/revised-appendices_cop15_e.pdf)
40. [IUCN SSC Otter Specialist Group. Sea otter (Enhydra lutris): species page.](https://www.otterspecialistgroup.org/otter-species/enhydra-lutris/)
41. [Doroff A, Burdin A, Larson S (2021). Enhydra lutris. The IUCN Red List of Threatened Species 2021: e.T7750A219377647.](https://doi.org/10.2305/IUCN.UK.2021-3.RLTS.T7750A219377647.en)
42. [IUCN SSC Otter Specialist Group. Eurasian otter (Lutra lutra): species page.](https://www.otterspecialistgroup.org/otter-species/lutra-lutra/)
43. [Loy A, Kranz A, Oleynikov A, Roos A, Savage M, Duplaix N (2022). Lutra lutra. The IUCN Red List of Threatened Species 2022: e.T12419A218069689.](https://doi.org/10.2305/IUCN.UK.2022-2.RLTS.T12419A218069689.en)
44. [IUCN SSC Otter Specialist Group. Neotropical otter (Lontra longicaudis): species page.](https://www.otterspecialistgroup.org/otter-species/lontra-longicaudis/)
45. [Rheingantz ML, Rosas-Ribeiro P, Gallo-Reynoso J, Fonseca da Silva VC, Wallace R, Utreras V, Hernández-Romero P (2022). Lontra longicaudis. The IUCN Red List of Threatened Species 2022: e.T12304A219373698.](https://doi.org/10.2305/IUCN.UK.2022-2.RLTS.T12304A219373698.en)
46. [GBIF. Pteronura brasiliensis in the IUCN Red List checklist dataset: vernacular names.](https://www.gbif.org/species/176684298)

## Measurements & details

- **Length:** 150-180 cm
- **Weight:** 20-35 kg
- **Lifespan:** 8-20 years
- **Litter Size:** 1-5
- **Gestation:** 64-77 days

## Diet & Feeding

Giant otters are expert fish hunters. Now and then they also eat crabs, snakes, turtles and young caimans.

- **Primary Foods:** Fish
- **Foraging Method:** Pursuit

## Ecological connections

- **Eaten by:** [Jaguar](https://www.snappit.app/explore/jaguar) (*Panthera onca*) — Jaguars rarely catch giant otters. The first confirmed case, in 2015, was a lone otter resting on a riverbank.
- **Hunts:** [Yacare Caiman](https://www.snappit.app/explore/yacare-caiman) (*Caiman yacare*) — Giant otters now and then catch young caimans, such as the yacare caiman in the Pantanal.
- **Hunts:** Peacock Bass (*Cichla temensis*) — Giant otters often catch cichlids, the fish family that includes peacock bass.
- **Hunts:** Spotted Catfish (*Pimelodus maculatus*) — Catfish are a common food source for giant otters.

## Traits

- [Furry](https://www.snappit.app/explore/traits/furry): Furry describes animals possessing a dense covering of soft hair or fur.
- [Webbed Feet](https://www.snappit.app/explore/traits/webbed-feet): Characterized by having toes connected by a membrane, typically aiding in swimming.
- [Social](https://www.snappit.app/explore/traits/social): Social animals live in organized groups, cooperating for survival benefits such as foraging, defense, and raising offspring.
- [Piscivorous](https://www.snappit.app/explore/traits/piscivorous): Piscivorous organisms are animals that primarily subsist on a diet of fish.
- [Wetland](https://www.snappit.app/explore/traits/wetland): This habitat trait identifies species found in wetlands, which are areas of land saturated with water, either permanently or seasonally, including marshes, swamps, and bogs.
- [Diurnal](https://www.snappit.app/explore/traits/diurnal): Diurnal animals are primarily active during daylight hours, typically resting or sleeping at night.
- [Freshwater](https://www.snappit.app/explore/traits/freshwater): Freshwater habitats include non-saline aquatic environments such as rivers, lakes, ponds, and wetlands, vital for numerous species.
- [Keystone Species](https://www.snappit.app/explore/traits/keystone-species): Describes a species whose presence and role have a disproportionately large effect on its environment.
- [Aquatic](https://www.snappit.app/explore/traits/aquatic): Aquatic habitats encompass environments where organisms live predominantly in water, including oceans, rivers, lakes, and wetlands.
- [Endangered](https://www.snappit.app/explore/traits/endangered): Endangered status indicates a species is at a very high risk of extinction in the wild in the near future.

## Collections

- [Mammals](https://www.snappit.app/explore/collections/mammals)

## Safety

**Danger:** 2/5 · Low

Giant otters are wild predators with strong teeth. Watch only from a boat or a viewing tower, stay at least 20–30 m away, and never chase, feed or touch them. If you see one up close, tell an adult.

## Frequently Asked Questions

### How to identify Giant otter?

Compare ears, muzzle, tail, feet and coat markings. Size is hard to judge without something nearby for scale, and young mammals may not have adult coloring yet. Mammal Identifier: upload a photo and compare the visible details.

### How long is Giant otter?

150-180 cm

### How much does Giant otter weigh?

20-35 kg

### How long does Giant otter live?

8-20 years

### What does Giant otter eat?

Giant otters are expert fish hunters. Now and then they also eat crabs, snakes, turtles and young caimans.

### Where is Giant otter usually found?

Wetlands

### How does Giant otter hunt?

Pursuit

### How many babies does Giant otter usually have?

1-5

## Where to spot

- [Birmingham Zoo](https://www.snappit.app/guides/places/birmingham-zoo) — Alabama, US · Zoo
- [Brevard Zoo](https://www.snappit.app/guides/places/brevard-zoo) — Florida, US · Zoo
- [Zoo Dortmund](https://www.snappit.app/guides/places/zoo-dortmund) — North Rhine-Westphalia, DE · Zoo
- [Los Angeles Zoo](https://www.snappit.app/guides/places/los-angeles-zoo) — California, US · Zoo
- [Bergzoo Halle (Zoologischer Garten Halle)](https://www.snappit.app/guides/places/bergzoo-halle) — Sachsen-Anhalt, DE · Zoo
- [Tierpark Cottbus](https://www.snappit.app/guides/places/tierpark-cottbus) — Brandenburg, DE · Zoo

[View all places to see Giant otter](https://www.snappit.app/guides/where-to-see/giant-otter)

## More Mammals

- [Eastern Fox Squirrel](https://www.snappit.app/explore/eastern-fox-squirrel) (*Sciurus niger*)
- [Eastern Cottontail](https://www.snappit.app/explore/eastern-cottontail) (*Sylvilagus floridanus*)
- [Eastern Chipmunk](https://www.snappit.app/explore/eastern-chipmunk) (*Tamias striatus*)
- [California Ground Squirrel](https://www.snappit.app/explore/california-ground-squirrel) (*Otospermophilus beecheyi*)

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Source: [Giant otter: Facts & Places to See — Snappit](https://www.snappit.app/explore/giant-otter)