alligator beneath cayman croc crocodile danger fear fresh gator reptile salt saltwater submerged sveres teeth underneath underwater water armor armored armorment armour armoured armourment backstraps bony ridges crocodylus-porosus dangerous dorsal-surface estuarine-crocodile exotic fauna hide hornback huge Indo-Pacific-crocodile large largest-reptile leather leathery lethargic omnivorous opportunistic opportunistic-predator osteoderms patterns powerful predator reptilian ridges rough rugged saltwater-crocodile scales scutes skin tail tail-scutes territorial texture textured textures hunter