|
|||
ChameleonsChameleons (family Chamaeleonidae) are squamates that belong to one of the best-known lizard families. The name "chameleon" means "Earth lion" and is derived from the Greek words chamai (on the ground, on the earth) and leon (lion).DescriptionChameleons vary greatly in size and body structure, with total length from approximately 1 in (2 cm) in Brookesia minima, to the 31 inches (79 cm) in male Furcifer oustaleti. There is even one species, thought to be unique to Malawi's Mount Mulanje, which is barely 0.6 in (1 cm) across when fully grown[citation needed]. Many have head or facial ornamentation, be it nasal protrusions or even horn-like projections in the case of Chamaeleo jacksonii, or large crests on top of their head, like Chamaeleo calyptratus. Many species are sexually dimorphic, and males are typically much more ornamented than the female chameleons.The main things chameleon species do have in common is their foot structure, their eyes, their lack of ears, and their tongue. Their eyes are the most distinctive among the reptiles. The upper and lower eyelids are joined, with only a pinhole large enough for the pupil to see through. They can rotate and focus separately to observe two different objects simultaneously. It in effect gives them a full 360-degree arc of vision around their body. When prey is located, both eyes can be focused in the same direction, giving sharp stereoscopic vision and depth perception. They lack a vomeronasal organ. Also, like snakes, they don't have an outer or a middle ear. This suggests that chameleons might be deaf, although it should be noted that snakes can hear using a bone called the quadrate to transmit sound to the inner ear. Furthermore, some or maybe all chameleons, can communicate via vibrations that travel through solid material like branches. Chameleons have incredibly long tongues (sometimes longer than their own body length) which they are capable of rapidly and abruptly extending out of the mouth. The tongue whips out faster than our eyes can follow, speeding at 26 body lengths per second. The tongue hits the prey in about 30 thousandths of a second — one tenth of an eye blink.The tongue has a sticky tip on the end, which serves to catch prey items that they would otherwise never be able to reach with their lack of locomotive speed. The tongue's tip is a bulbous ball of muscle, and as it hits its prey, it rapidly forms a small suction cup. Once the tongue sticks to a prey item, it is drawn quickly back into the mouth, where the chameleon's strong jaws crush it and it is consumed. Even a small chameleon is capable of eating a large locust or mantis. Ultraviolet light is actually part of the visible spectrum for Chameleons. Primarily, this wavelength affects the way a chameleon perceives its environment and the resultant physiological effects. Chameleons exposed to ultraviolet light show increased social behavior and activity levels, are more inclined to bask and feed and are also more likely to reproduce as it has a positive effect on the pineal gland.
|
|||
|
© Deepthi.com, 2003-2005. All Rights Reserved.
Contact webmaster@deepthi.com for comments and suggestions.
India India Cricket India Bollywood |
|||
