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مشاهدة النسخة كاملة : تقريرانجليزي عن Rattlesnake



الفارس الشمري
28-04-2010, 06:55 PM
Rattlesnake




There are approximately thirty species of rattlesnake,
with numerous subspecies. They receive their name for
the rattle located at the end of their tails. The rattle is
used as a warning device when threatened. The scientific
name Crotalus derives from the Greek, κρόταλον,
meaning "castanet". The name Sistrurus is the Latinized

form of the Greek word for "tail rattler" (Σείστρουρος,
Seistrouros) and shares its root with the ancient
Egyptian musical instrument, the sistrum, a type of rattle.
Most rattlesnakes mate in the spring. All species give
live birth, rather than laying eggs. The young are self-
sufficient from birth. Since they do not need their mother
after birth, the mother does not remain with her young.
However, at least one captive study has demonstrated
that females and their neonates show some level of
affinity for each other's company and will cross barriers
to reunite if separated.
Contrary to popular myth, rattlesnakes are not deaf. In
fact, the structure of their inner ears is very much like
that of other reptiles. They do, however, lack external
ears. Sound (whether from air or ground vibration) is
transmitted to the snake's inner ear via bone and muscle.