#090 Shellder
Shellder's artwork for Pokémon FireRed and LeafGreen.
Category Bivalve Pokémon
Original Region Kanto
National Dex Nr. #090
Kanto Dex Nr. #090
Johto #171
Kalos #136 (Coastal)
Generation 1
Pokémon Color Purple
Type(s) Water
Ability/ies Shell Armor, Skill Link
(Hidden: Overcoat)
Average Height 1'00"
Average Weight 8.8 lbs.
Evolves From N/A
Evolves Into Cloyster

Shellder, known in Japan as シェルダー (Shellder) is a Water-type Pokémon resembling a clam. It will evolve into Cloyser when a Water Stone is used on it.


Shellder can be described as a black, circular mollusk inside a purple bivalve shell, with each half decorated by two blunt spikes. The black body inside the shell features two large eyes with small pupils, as well and enormous tongue. Shellder's black body is soft and extremely tender. However, its shell is said to be harder than diamond, so it usually keeps the shell as closed as possible in order to prevent its squishy body from being exposed. Because Clamping exposes its body to its enemies, it usually Clamps as a last resort.

Shellder swims under the sea by repeatedly opening and closing its two shells, as if it were moving backwards. While doing so, it always keeps its tongue hanging out, and despite this, Shellder can swim very quickly. Shellder's tongue isn't actually a hindrance; it can be used as a limb-like tool by digging a hole on the sea floor so Shellder can hide in it. Shellder usually does this at night-time, when it's going to sleep, but still keeps its tongue exposed after burying itself. Shellder does the same thing when it's hunting for prey, using its tongue as a bait. Occasionally, grains of sand fall into its bivalve shell when it's buried. These grains will mix with its body fluids and become shiny pearls as a result.

Relations with Slowpoke

Shellder can form a symbiotic relationship with Slowpoke; when a Shellder clamps a Slowpoke's tail or head, the Slowpoke will evolve into Slowbro or Slowking, respectively, and the Shellder in turn becomes a gray, menacing-looking conch shell with fangs. Shellder morphs so drastically that it might as well be a new evolution of sorts.

A Shellder that bit a Slowpoke's tail becomes a gray turban shell with four segments, with its eyes and teeth located on the biggest segment and the tip being the smallest segment. The biggest segment also has a lower jaw that can only be seen when looking behind Slowbro. Each segment features curved spikes and several darker spots. This Shellder won't let loose of Slowbro's tail because of its taste, and each time it bites, it injects a secretive poison that benumbs Slowbro off pain completely. Because Shellder now occupies Slowbro's tail, Slowbro now has to hunt prey manually, letting the Shellder feed on leftover scraps.

When Slowbro Mega Evolves, it is especially the Shellder that alters, due to Mega Slowbro's energy being gathered in the Shellder. The Shellder will completely engulf Slowbro, safe for head and arms, as it loses its jaw for a rim of serrated teeth, and also loses the smallest segment for room for Slowbro's tail. The curved spikes are gone, and replaced by four straight spikes on the now-smallest segment. Shellder has become an armor for Slowbro, as it grew so hard that even the harshest attack won't leave a single scratch.

When a Shellder bites a Slowpoke's head when Slowpoke is wearing a King's Rock, Shellder becomes a different-looking conch. While still being a turban shell, this conch only has three segments from the get-go, and no spots. The tip of the shell is adorned with several spikes and a red jewel on its underside, making this segment resemble a small crown. Its lower jaw is more visible now, but each side is adorned with a curved spike so big, it resembles a tusk. This Shellder also has less fangs, which are arguably smaller too. The entire Shellder looks like a crown overall for Slowking.

Each time Shellder bites in Slowking's head, it releases a quantity of venom in its brain, which causes Slowking to become extremely intelligent. Slowking becomes even more intelligent when it awns, because its yawning causes Shellder to release even more poison. When the Shellder gets off the head, however, Slowking reverts to a Slowpoke and forgets everything it has learned.


  • Shellder and Cloyster share their category with Clamperl. All three Pokémon are categorized as the Bivalve Pokémon.


Shellder seems directly inspired by the clam, with its tongue representing the foot of the clam. Its behavior to Slowpoke is more similar to leeches, as it latches onto Slowpoke and releases beneficial toxins.

Name Origin

Shellder's name comes from shell, and possibly shelter.

Names in other Languages

Language Name Meaning
From shell and shelter.
FrenchKokiyasFrom coquille and as
GermanMuschasFrom Muschel




National Pokédex
← #089: Muk
#090: Shellder
#091: Cloyster →
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