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Sea Beasts are a class of large aquatic mammals that inhabit the Grand Line, notable for their uncanny resemblance to surface mammals. The first Sea Beast encountered in the series is the Sea Cow Momoo.[1]

Though somewhat similar in habitats and behavior, they should not be confused with Sea Kings, the (generally) larger and more vicious non-mammals that also inhabit the world's oceans.[2]



Their appearance is generally based around mammalian surface animals, such as cats, cows, elephants and many other kinds of mammals. The main difference between them and their surface counterparts are the added scales along their bodies, their fish-like fins and tail fin instead of legs and/or tails, and the ability to breath underwater through presumably gills. The majority of sea beasts are gigantic in size, easily being around the size of a kraken (which can have an estimated length of 300m (984')) and even their young can be quite huge. However smaller sea beasts, such as the Sea Squirrel exist as well which are only a bit larger than humans.


While not as aggressively carnivorous as Sea Kings (which are, in fact, one of their natural predators), most Sea Beasts will indiscriminately attack smaller animals, including both humans and merfolk. Nevertheless, they are much easier for powerful individuals to intimidate and domesticate; around Fish-Man Island in particular, they are commonly captured and harnessed by experienced pirates for underwater transportation,[3] with the New Fish-Man Pirates being known to own an entire pack.[4]

In addition, at least a few types of Sea Beasts have displayed high enough intelligence and sapience to form their own underwater towns, complete with law enforcement systems.[5]


Sea Cow

Sea cow detailed biology.

Sea Cows (海牛 Kaigyū?) greatly resemble normal, land-based cows, with curved horns, fleshy noses, and "patchy" coloring—though they are still carnivorous, with appropriately sharp teeth.[1] So far, the only known specimen is Momoo of the Arlong Pirates, who stands at a height of 36 meters (118'1" feet) and a weight of 16 tons (32,000 lbs).[6]

They are classified as type "A" creatures "Big Friendly".[7] This stands somewhat in contrast with their behavior of attacking and overturning ships, though it has been indicated that they do not actually eat human beings.[6]

Sea Cows are the only Sea Beasts known to be capable of moving on land (as the Arlong Pirates had—implicitly—let Momoo rampage inland through Gosa Village). The fish-like scales on their bodies are actually their hardened skin, protecting their vital organs from external attacks as an armor. Besides helping them swim as fast as 70 km/h (43.5 mps), their fins contain retractable bones, sharp enough to act as claws.

Just like normal cows, sea cows have four stomachs; bacteria and parasites dwell inside them, digesting anything the cows choose to eat, including poison from venomous animals, making these creatures essentially immune to food poisoning.[6]

Their name may be a pun on real-life dugongs and manatees, which are commonly referred to as "sea cows".

Sea Cat

Sea Cat

Sea Cats (海ネコ Umi Neko?, Cat Sharks in the 4Kids-dubbed anime), like ordinary cats, possess large, pointed ears, slit-pupiled eyes, distinct philtrum lips, and frontal limbs ending in paws—which they sometimes raise in a "beckoning" gesture, akin to a maneki-neko, on surfacing.[8] While grown specimens are as large as any other Sea Beast, juveniles—the only juvenile Sea Beasts depicted thus far—are "only" slightly larger than the 3.01m (9'10") Jinbe.[9]

They are classified as a type "A" creature, "Big Friendly".[7] Despite their preying on ships, the Kingdom of Arabasta considers them religiously significant ("endangered" in the 4Kids dub), and strictly forbids them from being harmed.[8] Notably, the Tomb of the Kings contains multiple statues carved in their likeness.[10]

Their name may be a reference to the black-tailed gull, colloquially known as "Sea Cats" (海猫 Umi-neko?) in Japan due to their cat-like calls.

Sea Boar

A sea boar that was saved by Hatchan.

A Sea Boar (海イノシシ Umi Inoshishi?) appeared in Hatchan's cover story where Hatchan saved it from an attacking sea monster. It turns out that earlier the sea boar had eaten Camie and Pappag and spat them out shortly after being rescued.[11]

Sea Monkey

A group of sea monkeys.

The Sea Monkeys (シーモンキー Shī Monkī?) are sea creatures with monkey-like faces. Found after returning from Skypiea and before arriving at Long Ring Long Land island, they have powerful flippers that can cause tidal waves. The Fanged Toad Pirates' ship sank due to the waves they created.[12]

They may be a reference to the "Sea-Monkey" shrimp marketed as novelty pets by many American toy companies (hence their species name being rendered purely in katakana—a convention used for no other Sea Beast).

Sea Raccoon

A Sea Raccoon (海ダヌキ Umi Danuki?, literally "sea tanuki") differs between the anime and the manga. Both versions are visual puns on "umidanuki", the Japanese word for beaver.

In the manga, it is a giant Sea Beast,[13] while in the anime, it is a shapeshifting animal. However, its transformations are limited to its original size, roughly that of a real raccoon, such as transforming into a doll-sized Nami. Lina is the only known person to own a sea raccoon. She and her pet, Nukky, appeared in the Spa island filler arc with her sister Sayo.[14]

Sea Raccoon in the Manga.png
A Sea Raccoon in the manga.
Nukky Anime Infobox.png
A Sea Raccoon in the anime.

Sea Rabbit

Sea Rabbit

A Sea Rabbit (海兎 Umi Usagi?) is a sea creature resembling a lagomorph. One was discovered near the Red Line by Luffy, Brook, and Robin traveling in the Shark Submerge III, which consequently was defeated by a Gomu Gomu no Rifle. Upon defeat, it spits out Camie and Pappag.[15] It's birthday is October 19th.[16]

Sea Hippo

Sea Hippo

A Sea Hippo (海カバ Umi Kaba?) is a massive sea creature with the face of a hippo. There was a Sea Hippo among the victims of the Stomach Baron.[17]

Sea Lion

The New Fish-Man Pirates' Sea Lion.

Sea Lions (海獅子 Umi Jishi?) possess faces and manes like those of normal lions (though, unlike Sea Cats, all four of their limbs end in flippers). By estimate, a typical adult is 55m (180' 5") long.[18]

Thus far, the only specimen depicted was part of the New Fish-Man Pirates' army.[4] which was later ridden by the Flying Pirates during their attack at Ryugu Kingdom.[19] After the New Fish-Man Pirates were beaten, the sea lion and its fellow sea monsters went on to cause havoc by going on a rampage.[20]

It may be based on the sea-lion, a mythical creature in heraldry with of the head and front limbs of a lion with the tail of a fish, or the merlion, another mythical creature with the head of a lion and the body of a fish. It is a visual pun on real-life "sea lions".

Sea Bear

The New Fish-Man Pirates' Sea Bear.

Sea Bears (海熊 Umi Guma?) possess faces and fur like those of normal bears. By estimate, a typical adult is 50m (164') long.[21]

The only one seen is under the command of the New Fish-Man Pirates, and it appeared first alongside the Sea Lion and many other sea beasts under the crew's command.[4] It was on a rampage, but stopped when some fish-men tried to frighten it with fire.[22]

The kanji for sea bear can mean "fur seal" in Chinese, which the sea bear somewhat resembles.

Sea Pig

Sea Pigs (海ブタ Umi Buta?) possess faces like those of normal pigs.[23] They are notable as the key ingredient in at least one Attack Cuisine dish: the Hormone Soup with Sea Pork.[24]

The name may be a pun on the Japanese word for dolphin (海豚 Iruka?), the kanji of which literally translates to "sea pig".

Sea Dog

Sea Beast Sheriff

Sea Dog (海イヌ Umi Inu?) is a Sea Beast resembling a dog. In Solo Journey of Jinbe, Knight of the Sea, one is seen working as a police officer, wearing a police hat and badge, and even having a mustache.[25]

Other Variants

Though not (yet) formally named, several other Sea Beasts were depicted among the New Fish-Man Pirates' forces, including:

  • A Sea Giraffe, which served as Hammond's—and later Hody Jones'—primary steed.
  • A Sea Elephant, which served as Dosun's primary steed.
  • A Sea Rhinoceros, which served as Zeo's primary steed.
  • A Sea Gorilla, which served as Hyouzou's primary steed.
  • A Sea Squirrel, which Hammond—unsuccessfully—tried to send against Luffy.
  • A Sea Leopard.

The unnamed Sea Beasts that served under the New Fish-Man Pirates.

After the New Fish-Man Pirates fell, most if not all of these joined the Sea Lion and the Sea Bear in an underwater town some distance from Fish-Man Island.

Later, several more Sea Beasts were encountered by Jinbe during his encounter with the aforementioned town, including:

It is unknown whether these Sea Beasts were also part of the New Fish-Man Pirates, or if they simply flocked together out of instinct.

Translation and Dub Issues

The Viz manga initially translated Momoo's class as the more generic "sea monster", with the term "Sea Beast" not being used until the translation of Volume 17's SBS (which confirmed that Momoo and creatures like him belonged to a category distinct from Sea Kings).[1] Interestingly, the original Japanese term, Kaijū (海獣?), is used in real life for ordinary marine mammals such as dolphins and whales; it remains unknown whether those of One Piece (e.g. Laboon) are also categorized as such.[26]

(As an aside, it should be noted that this Kaijū is not the Kaijū (怪獣?) used to describe Godzilla and other classic Japanese film monsters, though the two are homonymous.)


  1. 1.0 1.1 1.2 1.3 One Piece Manga and Anime — Vol. 9 Chapter 73 and Episode 33, Momoo makes his debut, and is identified as a "Sea Beast" (海獣 Kaijū?) by Yosaku. Note that Viz Media translated this instance as "sea monster", and did not use the "Sea Beast" terminology until the Volume 17 SBS.
  2. SBS One Piece Manga — Vol. 17 (p. 66), Oda explains that Momoo is a Sea Beast, a class of creatures distinct from Sea Kings.
  3. One Piece Manga and Anime — Vol. 62 Chapter 604 and Episodes 523524, On the way to Fish-Man Island, the Straw Hat Pirates see Momoo being forced to tow the Caribou Pirates' ship. Later, Caribou claims that many pirates tame Sea Beasts like this for the journey.
  4. 4.0 4.1 4.2 One Piece Manga and Anime — Vol. 62 Chapter 607 and Episodes 526527, A small delegation of the New Fish-Man Pirates, led by Hammond, have a half-dozen Sea Beasts surround the Straw Hat Pirates just outside Fish-Man Island.
  5. One Piece Manga — Vol. 75Vol. 78 Chapters 752780, cover story: Solo Journey of Jinbe, Knight of the Sea Vol. 2-24, Jinbe helps a community of Sea Beasts rebuild their hometown.
  6. 6.0 6.1 6.2 One Piece Magazine Vol.1
  7. 7.0 7.1 One Piece Blue: Grand Data File (p. 88-89), Classification of animals by dangerousness.
  8. 8.0 8.1 One Piece Manga and Anime — Vol. 18 Chapter 157 (p. 2-4) and Episode 92, A Sea Cat ambushes the Going Merry off the shore of Arabasta, but immediately retreats on seeing that Luffy and Zoro intend to eat it. When the Straw Hats try to pursue, Vivi bludgeons them.
  9. One Piece Manga — Vol. 75 Chapter 752, cover story: Solo Journey of Jinbe, Knight of the Sea Vol. 2, Jinbe encounters a juvenile Sea Cat whose hometown has been destroyed.
  10. One Piece Manga and Anime — Vol. 22 Chapter 202 (p. 8) and Episode 123, Nico Robin forces Nefertari Cobra to lead her into the Tomb of the Kings. The anime extrapolates that the switch to open the mausoleum's secret entrance is also built into a Sea Cat statue.
  11. One Piece Manga — Vol. 21 Chapter 193, cover story: Hatchan's Sea-Floor Stroll Vol. 11, Hatchan saves a Sea Boar from a sea monster.
  12. One Piece Manga and Anime — Vol. 32 Chapter 303 and Episode 207, The Fanged Toad Pirates sunk from a wave created by Sea Monkeys.
  13. One Piece Manga — Vol. 50 Chapter 490, A Sea Raccoon is introduced as a specific Sea Beast.
  14. One Piece Anime — Episode 382, An anime Sea Raccoon is introduced, and his abilities explained.
  15. One Piece Manga and Anime — Vol. 50 Chapter 490 and Episode 385, A Sea Rabbit is introduced.
  16. Vivre Card - One Piece Visual Dictionary (Card #0493), The Sea Rabbit's birthday is revealed.
  17. One Piece Manga and Anime — Vol. 60 Chapter 591 and Episode 507, A Sea Hippo is captured by the Stomach Baron.
  18. One Piece 15th Anniversary: Dive to Grand World, Its length is revealed.
  19. One Piece Manga and Anime — Vol. 63 Chapter 616 and Episode 535, Decken and the Flying Pirates rode on the Sea Lion.
  20. One Piece Manga — Vol. 76 Chapter 761, cover story: Solo Journey of Jinbe, Knight of the Sea Vol. 10, Jinbe reads about Sea Beasts rampaging.
  21. One Piece 15th Anniversary: Dive to Grand World, Its length is revealed.
  22. One Piece Manga and Anime — Vol. 64 Chapter 630 and Episode 550, The New Fish-Man Pirates calm the Sea Bear down.
  23. One Piece Manga — Vol. 78 Chapter 776, cover story: Solo Journey of Jinbe, Knight of the Sea Vol. 21, A Sea Pig is among the Sea Beasts taking misguided revenge on human ships.
  24. One Piece Manga and Anime — Vol. 70 Chapter 696 and Episode 622, Sanji makes Hormone Soup with Sea Pork to revitalize everyone after the battles on Punk Hazard.
  25. One Piece Manga — Vol. 76 Chapter 753, cover story: Solo Journey of Jinbe, Knight of the Sea Vol. 3, The Sea Beast Sheriff debuts.
  26. See Ja.Wiki on 海獣.

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