above water Ears eye head herbivore herbivorous hide hippo hippopotamus hippopotamus amphibius light mammal nostrils observant observing pool reflection reflections ripples rippling river horse semi-submerged shadows shiny skin submerged sunlight sunshine surface water wet hippopotami armor armored armorment armour armoured armourment Australian-freshwater-crocodile backstraps bony-ridges crocodile crocodylus-johnsoni danger dorsal-surface exotic fauna fresh-water-crocodile freshie Johnstone's-crocodile leather leathery lethargic omnivorous opportunistic opportunistic-predator osteoderms patterns powerful predator reptile reptilian ridges rough rugged scales scutes tail tail-scutes territorial texture textured textures