CROCODILES

Crocodiles (subfamily Crocodylinae) or true crocodiles are large semiaquatic reptiles that live throughout the tropics in Africa, Asia, the Americas and Australia. Crocodylinae, all of whose members are considered true crocodiles, is classified as a biological subfamily. A broader sense of the term crocodile, Crocodylidae that includes Tomistoma, is not used in this article. The term crocodile here applies to only the species within the subfamily of Crocodylinae. The term is sometimes used even more loosely to include all extant members of the order Crocodilia, which includes the alligators and caimans (family Alligatoridae), the gharial and false gharial (family Gavialidae), and all other living and fossil Crocodylomorpha.

Although they appear similar, crocodiles, alligators and the gharial belong to separate biological families. The gharial, with its narrow snout, is easier to distinguish, while morphological differences are more difficult to spot in crocodiles and alligators. 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 and caimans. Another obvious trait is that the upper and lower jaws of the crocodiles are the same width, and the teeth in the lower jaw fall along the edge or outside the upper jaw when the mouth is closed; therefore, all teeth are visible, unlike an alligator, which possesses in the upper jaw small depressions into which the lower teeth fit. Also, when the crocodile's mouth is closed, the large fourth tooth in the lower jaw fits into a constriction in the upper jaw. For hard-to-distinguish specimens, the protruding tooth is the most reliable feature to define the species' family.[1] Crocodiles have more webbing on the toes of the hind feet and can better tolerate saltwater due to specialized salt glands for filtering out salt, which are present, but non-functioning, in alligators. Another trait that separates crocodiles from other crocodilians is their much higher levels of aggression.

Crocodile size, morphology, behaviour and ecology differ somewhat among species. However, they have many similarities in these areas as well. All crocodiles are semiaquatic and tend to congregate in freshwater habitats such as rivers, lakes, wetlands and sometimes in brackish water and saltwater. They are carnivorous animals, feeding mostly on vertebrates such as fish, reptiles, birds and mammals, and sometimes on invertebrates such as molluscs and crustaceans, depending on species and age. All crocodiles are tropical species that, unlike alligators, are very sensitive to cold. They separated from other crocodilians during the Eocene epoch, about 55 million years ago.Many species are at the risk of extinction, some being classified as critically endangered.

References

1  "Crocodilian Biology Database - FAQ - What's the difference between a crocodile and an alligator". Flmnh.ufl.edu. Retrieved 5 April 2009.

 2 Guggisberg, C. A. W. (1972). Crocodiles: Their Natural History, Folklore, and Conservation. Newton Abbot, England: David & Charles. p. 195. ISBN 978-0-715.

Wearing a watch on our left hand became almost a reflex action, but have you ever wondered why? Normally, these thoughts dont cross ones mind, we are used to wearing wrist watches on the left hand, and thats it.

 

If you observe carefully, you will notice that this rule has exceptions. Although most people wear watches on their left wrist, some wear it on the right. You might have also heard that men should wear their watches on the left hand while women should wear them on the right.

 

There is a logical and practical explanation for this, but the fact that most people wear watches on their left hands also has a historical background.

Historically, men used pocket watches up until early years of 20th century, while only women used wristwatches. Pocket watches became popular during wars, because they were useful for coordinating military activities. However, these watches were large for todays standards and were carried by officers in custom leather pouches that were strapped on their wrists. This was a necessity because watches had huge balancing wheels and were very fragile and could break easily.

 

In order to protect their chronometers from damage, it was best to keep them on the wearers less dominant hand. Since majority of people are right handed, in most cases watches were held in the left hand.

We covered the historical background of this question, now we shall proceed to the practical explanation. Here we must consider that not everyone wears their watch on the left wrist. Vast majority of people do, however a small fraction of people wearing it on the right wrist.

 

The logic here is that majority of people in the world are right handed, so when wristwatches became increasingly popular, users found it more convenient to wear their watches on the left wrist.

 

There is a simple reason behind this. You will use your dominant hand more often, and while working you can easily keep a check on the watch to your left. Also, wearing it on non-dominant hand makes it less susceptible to damaging, breaking, or injuring yourself.

 

The same principal applies for smart watches, and additionally it may be hard to operate the watch using your non-dominant hand. Some smart watch manufacturers even suggest you should wear the watch on your left hand, because of its design but also to enable its functions to work properly. Example for this is heart rate reading function that will only give accurate measurements if you wear the watch on your left hand.

Lastly, do women have to wear their watches on the right and men on the left hand?

 

This claim has no scientific backing. In some occasions women use watches more like a fashion accessory then a necessity, so this may be the reason they wear it on the right hand - to attract more attention to their style. I assume that this is just a stereotype or a cultural thing in certain communities.

 

If you are using a watch, you should wear it so it suits your convenience. People commonly wear it on the non-dominant hand. For this there are no strict rules, but only practical reasons, so the final decision is totally up to you!

 

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