Episode 3x15 - "Wingman": The southern hemispheric sea scorpion is seen via a flashback montage that includes a scene from Episode 2x08 - "Next Tuesday".
Notes[]
It has a filter-like mouth usually found in primitive aquatic herbivores, which is odd, since its incredible ferociousness is suggestive of a carnivorous diet. It seems able to breathe above water to some extent.