Gastrodon is a Pokémon based on a sea slug. It has two horns protruding from the sides of its head. Upon evolving, Gastrodon gains a third eye in the center of its forehead that is absent in its pre-evolution Shellos.
Gastrodon and its pre-evolution Shellos are examples of allopatric speciation, though they are still able to breed.
Gender differences
None.
Special abilities
If any part of a Gastrodon's boneless body is ever ripped or torn off, it can grow back in very little time.
Behavior
When its natural enemy attacks, it oozes purple fluid and escapes.
Gastrodon, the Sea Slug Pokémon and the evolved form of Shellos. Gastrodon inhabits the shallow tidal pools of the ocean, and its sturdy shell serves to protect its body.
Gastrodon, the Sea Slug Pokémon and the evolved form of Shellos. A sturdy shell covered Gastrodon's back long ago. Its cells still contain evidence of it today.
Both Shellos and Gastrodon have a beta back sprite in the game data; however, there are no front sprites for these forms, and neither can be captured in this form.
These beta forms both are similar to the pink, West Sea variations of Shellos and Gastrodon, possibly meaning that they were developed from the Generation III versions. This is fitting, as all regions from before Generation IV are west of Mt. Coronet.
Gastrodon's Platinum Pokédex entry states that "long ago, its entire back was shielded with a sturdy shell." Interestingly, the same beta backsprite mentioned above depicts it with a rock-like shell, covering its entire back.
In Double Team Turnover!, its Pokédex entry specifically refers to it having a "sturdy shell."
Gastrodon is classified as a purple Pokémon in the Pokédex, which is fitting, as purple is the color that results from mixing the primary colors of both its forms, pink and blue.
Origin
Gastrodon is based on a sea slug, perhaps specifically that in the order, Opisthobranchia.
The East Sea Gastrodon seems to be based on a Sea Hare. Though Gastrodon is unable to extract poisonous ink in a move form that it can learn naturally (though it can learn Slime Wave, Sludge Bomb, Sludge and Clear Smog by TMs, and from being fathered by members of other Pokémon species).
Name origin
Gastrodon's name is derived from "gastropod," the zoological category slugs and snails belong to, and "don," a Spanish honorific meaning leader or king, or in other words, king of snails and slugs.
The name Tritodon is derived from Tritoniidae. It may also come from the fact that eastern Gastrodon look like cows or oxen. The word Torito is Spanish for "little bull." Its name might mean "royal ox snail," referring to its strength.