Eye with Vision and Touch Sensors
The Gharials or Gavials (Gavialis gangeticus) are pure fish eaters, though a crab or two may be unlucky to be swallowed by these majestic river dwellers. They are the kings of few North Indian rivers, especially Ganges! Since they spend most of their time in water, their eyes are telescopic, placed well on top of their heads. This allows only their periscope-like eyes to come out of water when they surface. Also notice the thin translucent membrane called as 'Nictating Membrane' that is there in the frontal part of the eyes, ready to move backwards to protect the eyes once the animal is submerged. This acts as a water-screen or swimming goggles, which improves the vision of the submerged gharials. This morphological adaptation is there in all 23 crocodilian species around the world!
Seventh Sense: Note that their eyes with vertical pupil are bordered with small pressure sensors (clearly visible in the lower eyelid) that appear like dark spots. With these, they are able to assess the changes in water pressure around them and gives them better navigation and fishing efficiency even in darker and murkier waters, where vision might not be of great assistance. Moreover, these pressure sensors sense the movement of fish and other elements around their mouth (since their jaws are ridden with several of these), leading them to accurately catch fish. Even though this is an extension of touch mechanism, but can be recognized before touching something, since the fish are too smart to swim close to or touch a hungry gharial. The fish have a "lateral line" running along their body from mouth to tail that acts as their pressure sensing mechanism.
Fishing Strategies: Since both prey and predator have these, the predator has 3 strategies. It either waits without any movements for the fish to swim close by to swiftly snap shut its mouth and get its meal. Otherwise, it frightens and chases fish to nooks and corners close to the river beds and bends. Once they are trapped between its huge body and the bank, it feasts on them. The third way is to capture the overconfident huge fishes that do not care about the presence of this huge reptilian in their vicinity.
The dark slit behind the eye is its ear, which also is shut in a watertight manner after diving.
Eye with Vision and Touch Sensors
The Gharials or Gavials (Gavialis gangeticus) are pure fish eaters, though a crab or two may be unlucky to be swallowed by these majestic river dwellers. They are the kings of few North Indian rivers, especially Ganges! Since they spend most of their time in water, their eyes are telescopic, placed well on top of their heads. This allows only their periscope-like eyes to come out of water when they surface. Also notice the thin translucent membrane called as 'Nictating Membrane' that is there in the frontal part of the eyes, ready to move backwards to protect the eyes once the animal is submerged. This acts as a water-screen or swimming goggles, which improves the vision of the submerged gharials. This morphological adaptation is there in all 23 crocodilian species around the world!
Seventh Sense: Note that their eyes with vertical pupil are bordered with small pressure sensors (clearly visible in the lower eyelid) that appear like dark spots. With these, they are able to assess the changes in water pressure around them and gives them better navigation and fishing efficiency even in darker and murkier waters, where vision might not be of great assistance. Moreover, these pressure sensors sense the movement of fish and other elements around their mouth (since their jaws are ridden with several of these), leading them to accurately catch fish. Even though this is an extension of touch mechanism, but can be recognized before touching something, since the fish are too smart to swim close to or touch a hungry gharial. The fish have a "lateral line" running along their body from mouth to tail that acts as their pressure sensing mechanism.
Fishing Strategies: Since both prey and predator have these, the predator has 3 strategies. It either waits without any movements for the fish to swim close by to swiftly snap shut its mouth and get its meal. Otherwise, it frightens and chases fish to nooks and corners close to the river beds and bends. Once they are trapped between its huge body and the bank, it feasts on them. The third way is to capture the overconfident huge fishes that do not care about the presence of this huge reptilian in their vicinity.
The dark slit behind the eye is its ear, which also is shut in a watertight manner after diving.