Anatomy of Crocodile

Introduction of Crocodile

Species

Crocodiles (subfamily Crocodylinae) or true crocodiles are large aquatic reptiles that live throughout the tropics in Africa, Asia, the Americas and Australia. Crocodile, alligator often appear to be similar to the untrained eye. The most obvious external differences are visible in the head with crocodiles having narrower and longer heads, with a more V-shaped than a U-shaped snout compared to alligators.

Characteristic and Biology

1)  Streamlined Body

A crocodile’s physical traits allow it to be a successful predator. Its external morphology is a sign of its aquatic and predatory lifestyle. Its streamlined body enables it to swim swiftly, it also tucks its feet to the side while swimming, which makes it faster by decreasing water resistance. They have webbed feet which, though not used to propel the animal through the water, allow them to make fast turns and sudden moves in the water or initiate swimming.

2)  Senses

All crocodilians possess 'integumentary sense organs' (ISOs)- that is, sensory cells present in the integumentary layer (skin). ISOs can be found at the upper jaw, nose, around the eyes, lower jaw, even the upper palate. None of the other animal has this kind of sensory cells.Function and structureof ISOs varies depending on their position around the body. These ISOs are able to sense up to 20-35Hz, response within 50-100 milisecond. Those around the jaws are mechanoreceptors which can detect pressure changes. Almost certainly, these sense organs are used when the crocodile is underwater to sense the proximity of prey items. A fish swimming past the head of an alligator, for example, will fire the sense organs as pressure waves from its movement through water impinge upon the ISOs. It is likely that the wave of firing across the head of the alligator tells it where the pressure wave is coming from (i.e. a directional sense), and hence where the prey is.

                  

 3)  Vision

Crocodiles have very good night vision, and are mostly nocturnal hunters. They use the disadvantage of most prey animals' poor nocturnal vision to their advantage. The light receptors in crocodilians’ eyes include cones and numerous rods, so it is assumed all crocodilians can see colours. Crocodiles have vertical-slit shaped pupils, similar to domestic cats. One explanation for the evolution of slit pupils is that they exclude light more effectively than a circular pupil, helping to protect the eyes during daylight. On the rear wall of the eye is a tapetum lucidum, which reflects incoming light back onto the retina, thus utilizing the small amount of light available at night to best advantage. In addition to the protection of the upper and lower eyelids, crocodiles have a nictitating membrane (sometimes called a "third eye-lid") that can be drawn over the eye from the inner corner while the lids are open. The eyeball surface is thus protected under the water while a certain degree of vision is still possible.

4)  Skin

Crocodiles and alligators have rather different scales from those of other reptiles. Called 'scutes', they are bony and quite massive, but are not fused together joined to the underlying skeleton, so flexible fast movement is still possible. Each scute develops on its own, and is replaced by layers from below. The scutes are particularly massive on the back, perhaps because this is the area most exposed to the sun and most at risk of drying out. Where the scutes are larger, the area of less waterproof skin between is smallest, so large scutes provide a good seal against water loss. Areas of small scutes occur on the sides and around the shoulders and hips, where greater flexibility is needed during movement.

5)  Bite

Since crocodile feed by grabbing and holding onto their prey, they have evolved sharp teeth for piercing and holding onto flesh, and powerful muscles to close the jaws and hold them shut. The teeth are not well-suited to tearing flesh off of large prey items as is the dentition and claws of many mammalian carnivores, the hooked bills and talons of raptorial birds. However, this is an advantage to the crocodile since the properties of the teeth allow it to hold onto prey with the least possibility of the prey animal to escape. Otherwise combined with the exceptionally high bite force, the flesh would easily cut through; thus, creating an escape opportunity for the prey item. The jaws can bite down with immense force, by far the strongest bite of any animal. The force of a large crocodile's bite is more than 22,000 N, which was measured in a 5.5 m Nile crocodile, compared to just 1,490 N for a Rottweiler, 3,000 N for a great white shark.