Name a mammal or reptile that lives in rivers

The rarest possible answer — almost no player finds it.

• Mary River turtle— Grows green algae hair and breathes through its rear end.
• Rakali— Australia's native water rat, with a white-tipped tail.

Genuinely obscure. Most players never think of it.

• Adanson's mud turtle
• African brown water snake
• African clawless otter
• African dwarf mud turtle
• African forest turtle
• African helmeted turtle
• African keeled mud turtle
• African manatee
• African side-necked turtle
• African softshell turtle
• Alabama map turtle
• Alabama red-bellied cooter
• Amazon river turtle
• Amazonian manatee
• Amazonian nectomys
• Amboina box turtle
• American water shrew
• Annulated water snake
• Aquatic garter snake
• Aquatic genet
• Aquatic tenrec
• Arafura file snake
• Araguaian river dolphin
• Aramia snake-necked turtle
• Argentine snake-necked turtle
• Arrau turtle
• Asian giant softshell turtle
• Asian leaf turtle
• Asian narrow-headed softshell turtle
• Asian small-clawed otter
• Asiatic annulate keelback
• Asiatic softshell turtle
• Assam leaf turtle
• Assam roofed turtle
• Atrato slider
• Aubry's flapshell turtle
• Australian big-headed turtle
• Australian saw-shelled turtle
• Australian short-necked turtle
• Australian snake-necked turtle
• Australian snapping turtle
• Australian water dragon
• Baiji
• Baird's tapir
• Baja California slider
• Balkan pond turtle
• Banded water cobra
• Barbour's map turtle
• Barred grass snake
• Beale's eyed turtle
• Bellinger River snapping turtle
• Big Bend slider
• Big-headed Amazon river turtle
• Big-headed turtle
• Black marsh turtle
• Black pond turtle
• Black softshell turtle
• Black-knobbed map turtle
• Black-striped keelback
• Bocourt's water snake
• Bolivian anaconda
• Bolivian river dolphin
• Borneo crocodile
• Brahminy river turtle
• Brazilian snake-necked turtle
• Brazos water snake
• Broad-shelled turtle
• Brown roofed turtle
• Brown stream snake
• Brown water snake
• Brown-banded water snake
• Buff-striped keelback
• Burmese flapshell turtle
• Burmese keelback
• Burmese narrow-headed softshell turtle
• Burmese peacock softshell
• Burmese roofed turtle
• Bush dog
• Cagle's map turtle
• Caiman lizard
• Cameroonian wading rat
• Cann's snake-necked turtle
• Caspian turtle
• Central African mud turtle
• Central African slender-snouted crocodile
• Central American mud turtle
• Central American river turtle
• Central American snapping turtle
• Checkered keelback
• Chinese alligator
• Chinese crocodile lizard
• Chinese pond turtle
• Chinese softshell turtle
• Chinese stripe-necked turtle
• Chinese water dragon
• Chinese water shrew
• Chinese water snake
• Coastal plain cooter
• Colombian slider
• Concho water snake
• Congo clawless otter
• Congo wading rat
• Congo water cobra
• Cooter
• Crab-eating mongoose
• Crab-eating raccoon
• Crab-eating water snake
• Crayfish snake
• Crocodile tegu
• Cuban slider
• Cumberland slider
• D'Orbigny's slider
• Dahl's toad-headed turtle
• Dark-spotted anaconda
• Dice snake
• Dinner-plate turtle
• Diving lizard
• Dog-faced water snake
• Dumeril's monitor
• Dunn's mud turtle
• Dwarf caiman
• Dwarf crocodile
• Dwarf water cobra
• Earless monitor lizard
• Earless water rat
• East African black mud turtle
• East African wading rat
• Eastern long-necked turtle
• Eastern mud turtle
• Eastern water snake
• Ecuador fish-eating rat
• Ecuadorean crab-eating rat
• Elegant water shrew
• Elephant trunk snake
• Escambia map turtle
• Ethiopian amphibious rat
• Euphrates softshell turtle
• Eurasian otter
• False gharial
• False map turtle
• False water cobra
• Fanged water snake
• Ferreira's fish-eating rat
• File snake
• Fish-eating rat
• Fishing cat
• Fitzroy River turtle
• Flat-headed cat
• Flattened musk turtle
• Florida cottonmouth
• Florida green water snake
• Florida red-bellied cooter
• Florida softshell
• Four-eyed turtle
• Geoffroy's side-necked turtle
• Giant Asian pond turtle
• Giant beaver
• Giant garter snake
• Giant musk turtle
• Giant otter shrew
• Gibba turtle
• Glossy crayfish snake
• Golden coin turtle
• Goldman's water mouse
• Gorgas's rice rat
• Graham's crayfish snake
• Grass snake
• Greater cane rat
• Green water snake
• Gulf snapping turtle
• Hainan mountain keelback
• Hairy-nosed otter
• Hall's New Guinea crocodile
• Herrera's mud turtle
• Hilaire's side-necked turtle
• Himalayan water shrew
• Hoge's side-necked turtle
• Hunan softshell turtle
• Iberian grass snake
• Iberian pond turtle
• Indian black turtle
• Indian eyed turtle
• Indian flapshell turtle
• Indian narrow-headed softshell turtle
• Indian peacock softshell turtle
• Indian roofed turtle
• Indian softshell turtle
• Indian tent turtle
• Indonesian giant sailfin dragon
• Indus river dolphin
• Intermediate musk turtle
• Irrawaddy dolphin
• Irwin's turtle
• Ivory Coast mud turtle
• Jalisco mud turtle
• Jamaican slider
• Japanese otter
• Japanese pond turtle
• Japanese water shrew
• Jingdong water snake
• Keelback
• Khorat snail-eating turtle
• Las Cajas water mouse
• Leith's softshell turtle
• Lesser capybara
• Lesser Chinese softshell turtle
• Loggerhead musk turtle
• Lutrine opossum
• Madagascan big-headed turtle
• Magdalena River turtle
• Magdalena-Cauca water rat
• Malagasy hippopotamus
• Malayan flat-shelled turtle
• Malayan snail-eating turtle
• Malayan softshell turtle
• Malayan tapir
• Malayan water shrew
• Malaysian giant turtle
• Manchurian black water snake
• Mangrove monitor
• Manning River turtle
• Map turtle
• Marsh mongoose
• Marsh rice rat
• Massoia's lutrine opossum
• Matamata
• Maximilian's snake-necked turtle
• Mediterranean water shrew
• Mekong snail-eating turtle
• Merauke snapping turtle
• Mertens' water monitor
• Mesoamerican slider
• Mexican black-bellied garter snake
• Mexican mud turtle
• Mexican musk turtle
• Mexican water mouse
• Mississippi map turtle
• Mitchell's water monitor
• Modest keelback
• Moluccan sailfin lizard
• Montane fish-eating rat
• Morelet's crocodile
• Mountain tapir
• Mountain water rat
• Mountain water snake
• Mud snake
• Mud turtle
• Mugger crocodile
• Murray River turtle
• Musk turtle
• Myanmar brown leaf turtle
• Nabire snapping turtle
• Namoi River snapping turtle
• Narrow-bridged musk turtle
• Narrow-headed garter snake
• Nazas slider
• Neotropical otter
• New Britain water rat
• New Guinea bockadam
• New Guinea crocodile
• New Guinea giant softshell turtle
• New Guinea snake-necked turtle
• New Guinea snapping turtle
• New Guinea waterside rat
• Nicaraguan rice rat
• Nicaraguan slider
• Nile monitor
• Nimba otter shrew
• North American water vole
• Northern caiman lizard
• Northern Chinese softshell turtle
• Northern map turtle
• Northern New Guinea giant softshell turtle
• Northern red-bellied cooter
• Northern red-faced turtle
• Northern snake-necked turtle
• Northern snapping turtle
• Northern yellow-faced turtle
• Nubian flapshell turtle
• Oaxaca mud turtle
• Okavango mud turtle
• Oldham's leaf turtle
• Olive keelback
• Orinoco crocodile
• Orinoco mata mata
• Ornate slider
• Osborn's dwarf crocodile
• Otter civet
• Otter shrew
• Ouachita map turtle
• Pacific water shrew
• Painted terrapin
• Paraguayan caiman lizard
• Parker's snake-necked turtle
• Pascagoula map turtle
• Pearl River map turtle
• Peninsula cooter
• Philippine crocodile
• Philippine sailfin lizard
• Pig-nosed turtle
• Pine's crab-eating rat
• Pittier's crab-eating rat
• Plainbelly water snake
• Pritchard's snake-necked turtle
• Proboscis monkey
• Puff-faced water snake
• Queen snake
• Rainbow snake
• Rainbow water snake
• Razor-backed musk turtle
• Red-bellied short-necked turtle
• Red-crowned roofed turtle
• Red-headed Amazon river turtle
• Red-headed side-necked turtle
• Red-necked keelback
• Red-necked pond turtle
• Reimann's snake-necked turtle
• Rice paddy snake
• Ringed map turtle
• Rio Cauca anole
• Rio Grande cooter
• River cooter
• River terrapin
• Roofed turtle
• Rough-footed mud turtle
• Rough-necked monitor
• Ruwenzori otter shrew
• Sabine map turtle
• Sailfin lizard
• Sandstone snake-necked turtle
• Savanna side-necked turtle
• Saw-shelled turtle
• Scorpion mud turtle
• Senegal flapshell turtle
• Serrated hinged terrapin
• Shaw Mayer's water rat
• Siamese crocodile
• Side-necked turtle
• Six-tubercled Amazon river turtle
• Slender-snouted crocodile
• Smooth softshell
• Smooth-coated otter
• Smooth-fronted caiman
• Snake-necked turtle
• Sonora mud turtle
• South American snake-necked turtle
• South American snapping turtle
• South American tapir
• South American water rat
• South American water snake
• Southern river otter
• Southern river terrapin
• Southwestern pond turtle
• Southwestern snake-necked turtle
• Spectacled caiman
• Spiny softshell
• Spotted softshell turtle
• Spotted-necked otter
• Sri Lankan flapshell turtle
• Star-nosed mole
• Stolzmann's crab-eating rat
• Stripe-necked musk turtle
• Striped keelback
• Striped mud turtle
• Striped swamp snake
• Sulawesi black sailfin lizard
• Sumatran water shrew
• Sunda water shrew
• Suwannee cooter
• Suwannee snapping turtle
• Swamp eel snake
• Swamp rabbit
• Tabasco mud turtle
• Tentacled snake
• Texas cooter
• Texas map turtle
• Thomas's water mouse
• Three-striped roofed turtle
• Tiger keelback
• Toad-headed turtle
• Transcaucasian water shrew
• Trinidad water rat
• Tucuxi
• Tweedy's crab-eating rat
• Twist-necked turtle
• Ucayali water rat
• Underwood's water mouse
• Ungava seal
• Upemba mud turtle
• Vanderhaege's toad-headed turtle
• Variable mud turtle
• Vietnamese pond turtle
• Viperine water snake
• Voss' fish-eating rat
• Water anole
• Water chevrotain
• Water coral snake
• Water deer
• Water dragon
• Water mouse
• Water opossum
• Water python
• Water shrew
• Water skink
• Wattle-necked softshell turtle
• Weber's sailfin lizard
• West African black turtle
• West African crocodile
• West African mud turtle
• West African slender-snouted crocodile
• Western Amazonian nectomys
• Western pond turtle
• Western water rat
• White-bellied rice rat
• White-lipped mud turtle
• White-throated snapping turtle
• Wild water buffalo
• Williams' mud turtle
• Williams' side-necked turtle
• Wologizi wading rat
• Wood turtle
• Yacare caiman
• Yangtze finless porpoise
• Yangtze giant softshell turtle
• Yaqui slider
• Yellow anaconda
• Yellow mud turtle
• Yellow pond turtle
• Yellow-bellied mud turtle
• Yellow-bellied slider
• Yellow-blotched map turtle
• Yellow-headed temple turtle
• Yellow-spotted river turtle
• Yunnan water snake
• Zambezi flapshell turtle
• Ziegler's water rat
• Zulia toad-headed sideneck

Uncommon — only a minority of players land here.

• Alligator snapping turtle
• Amazon river dolphin
• American crocodile
• Basilisk
• Black caiman
• Desman
• Freshwater crocodile
• Ganges river dolphin
• Gharial
• Giant otter
• Green iguana— Lives in trees over rivers and dives in to escape danger.
• Manatee
• Mink
• Muskrat
• Nile crocodile
• Nutria
• Painted turtle
• Pygmy hippopotamus
• Red-eared slider
• River dolphin
• Saltwater crocodile
• Softshell turtle
• Tapir
• Water buffalo
• Water monitor
• Water vole
• West Indian manatee

A solid, middling pick shared with plenty of other players.

• Anaconda
• Caiman
• Capybara
• Cottonmouth
• Platypus
• Snapping turtle
• Turtle
• Water snake

The most common answer on the board.

• Alligator
• Beaver
• Crocodile
• Hippopotamus
• Otter