alligator, crocodile
鰐 centers on large aquatic reptiles with armored skin: alligators and crocodiles. The two meanings are essentially the same animal group, distinguished only by regional species.
鰐 combines 魚 (fish) with 咢, which likely contributes the sound. The character treats the crocodilian as a kind of fish-like creature, a common historical classification.
The left side 魚 (fish) suggests a water creature, and the right side 咢 looks like a wide mouth with sharp teeth. Picture a fish-like reptile with a huge, toothy jaw: an alligator or crocodile.
For ガク, imagine a crocodile snapping its jaws shut with a loud 'gaku!' sound. The sharp, sudden noise cues ガク while the crocodile's mouth closes.
crocodile; alligator
African slender-snouted crocodile (Crocodylus cataphractus)
American crocodile (Crocodylus acutus)
Orinoco crocodile (Crocodylus intermedius)
freshwater crocodile (Crocodylus johnsoni); Australian freshwater crocodile; Johnston's crocodile
Nile crocodile (Crocodylus niloticus)
Philippine crocodile (Crocodylus mindorensis)
American alligator (Alligator mississippiensis)
knock-kneed; pigeon-toed
walking with feet pointing outward
Toyotamaphimeia machikanensis (Japanese fossil species of crocodilian)
Chinese alligator (Alligator sinensis)
mugger crocodile (Crocodylus palustris); marsh crocodile; Indian crocodile; Indus crocodile; Persian crocodile
sand tiger shark (Carcharias taurus); gray nurse shark
alligator snapping turtle (Macroclemys temminckii)
wide mouth
avocado (Persea americana); alligator pear
crocodile or alligator skin (hide)
crocodile; alligator; crocodilian
ferocious shark