Grenchlers are water-based hunters native to Torvus Bog. These powerful predators have impressive natural might and are extremely aggressive.
When hunting, a Grenchler hides and then springs onto prey when it draws near. Grenchlers are amphibious, and can both jump to impressive heights and swim in pursuit of Samus or other prey. The Grenchler has two main attacks: it can both bite and fire an electrical blast at Samus. The beast has one weak spot, which is caused by a genetic defect. That is, its back armor is vulnerable to explosive weaponry. Once its armor is gone, its exposed flesh can be targeted by Samus.
Grenchlers are reptilian, bipedal lizards with armor and horns. The Grenchlers are gray, have a red underbelly, and a blue tongue. There are nine eyes on either side of their heads: eight on the upper jaw, and one on the lower jaw. They have several horns: one on their snout, two on the back of their head, and a large amount of spikes on their back armor. This makes the Grenchler very similar to Baby Sheegoths in appearance and attacks.
- "Water-based reptilian predator. Well armored and deadly at any range. Its back shell is vulnerable to explosive blasts, however.
The amphibious Grenchler lurks in marsh areas in search of prey. Fearless, it will spring from hiding and attack anything that moves. If it is unable to fell its prey with its powerful jaws, it will fire a potent burst of energy at them. Grenchlers have one weak spot - a genetic defect makes the shell on their back susceptible to explosive blasts. Remove the shell to expose a vulnerable nerve center, then target it to eliminate the creature." — Logbook "Grenchler" (Metroid Prime 2: Echoes)