苏萦-
Like all reptiles, snakes are “cold-blooded”. This term is related to their means of maintaining a stable body temperature- one that they need to function properly. Unlike mammals, snakes cannot produce their own body heat and prefer to operate at about 25-30 degrees C, depending on the species. Snakes keep their body temperature within this range by shuttling between warm and cool places- in cold weather or early in the morning they seek sunshine, and in very hot conditions they hide under stones or in burrows and are mostly nocturnal. In cold parts of the world snakes become inactive and hibernate till warmer days come, in order to avoid the low temperatures.
There are several notable facts, related to the anatomy of a snake. First, it has no legs. Then, they have no eyelids but most species have a transparent scale, known as brille, that covers their eyes. Furthermore, snakes have a single row of specialized ventral scales running along their undersides (actually, the whole body is covered in scales that vary in number, size and shape; they are certainly an aid to identification of the snake). The jawbones of snakes are loosely connected and can be disconnected temporarily when swallowing. The skin is very elastic. This allows them to stretch their mouths to a formidable extent and swallow prey larger than their heads. The heads of different snake species vary in shape and some snakes (boas, pythons, pit vipers) have an additional sense organ on their face- the heat pits. The very name suggests that this organ is involved in the detection of heat. Its function is to pinpoint the location of warm-blooded animals, even in complete darkness, so the snake can swallow them easily.
The eyesight and hearing of snakes are not very good. Maybe this is the reason why they have evolved additional senses. Snakes flick their tongues, thus picking scent particles from the air, and then withdraw them into the mouth. There are a couple of small chambers in the root of the mouth, where snakes place each fork of the tongue. These chambers form the Jacobson"s organ, which is connected direct to the brain. The tongue and the Jacobson"s organ enhance the sense of smell.
Snakes feed on different animals. Some very large species can eat mall deer and even crocodiles but most snakes usually prefer smaller pray- mice, rats, frogs, lizards and fish. Besides, snakes have different methods for killing their prey- boas and pythons constrict it and venomous snakes use their fangs to inject powerful venom that will kill the prey quickly and efficiently.
Snakes have interesting defensive behavior. Some are very well camouflaged (e.g. tree snakes may be green or brown and desert snakes may be yellow or light brown, etc.). Others are brightly colored with intricate or contrasting bands of red, yellow, black, white etc. This coloration serves as a warning signal to enemies. It can also confuse predators as to which direction the snake is moving, since different colors blend at high speed.
Many snakes bite in defense or hiss and puff their bodies to appear fiercer than they actually are. The rattlesnakes use a very peculiar way of warning their enemies. By vibrating their tails, they produce a loud buzzing noise that probably says: “Stay away! I am dangerous!”. A question that may arise here is what are the rattles… Well, they are actually remains of old skin that are trapped by a constriction at the end of the tail after each shedding. A new segment is added to the rattle after each skin shedding and the snake gets longer.
Snakes are well adapted to their habitats. There are entirely aquatic snakes, burrowing snakes and arboreal snakes. The variety of size, shape and color is due to the different mode of life. Snakes are especially concentrated in hot and dry places of the world.
Many snakes are becoming rare and endangered and collecting, let alone killing them, is illegal. The main reason is the destruction of their natural habitats as a result of agriculture, urbanization and road building. Snakes, however, can play a very important role in agriculture. They control the population of harmful rodents and pests, thus helping people. Though sometimes dangerous, snakes can be useful, and, as any living creature, they have the right to exist.
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wio-
All snakes are carnivorous, eating small animals including lizards and other snakes, rodents and other small mammals, birds, eggs or insects. Some snakes have a venomous bite, which they do use to kill their prey before eating it. Other snakes kill their prey by constriction. Still others swallow their prey whole and alive. Most snakes are very easy to feed in captivity, apart from a minority of species.
Snakes do not chew their food and have a very flexible lower jaw, the two halves of which are not rigidly attached, and numerous other joints in their skull (see snake skull), allowing them to open their mouths wide enough to swallow their prey whole, even if it is larger in diameter than the snake itself. It is a common misconception that snakes actually dislocate their lower jaw to consume large prey.
After eating, snakes become torpid while the process of digestion takes place. Digestion is an intensive activity, especially after the consumption of very large prey. In species which feed only sporadically, the entire intestine enters a reduced state between meals to conserve energy, and the digestive system is "up-regulated" to full capacity within 48 hours of prey consumption. So much metabolic energy is involved in digestion that in Crotalus durissus, the Mexican rattlesnake, an increase of body temperature to as much as 14 degrees Celsius above the surrounding environment has been observed.[2] Because of this, a snake disturbed after having eaten recently will often regurgitate its prey in order to be able to escape the perceived threat. However, when undisturbed, the digestive process is highly efficient, dissolving and absorbing everything but hair and claws, which are excreted along with uric acid waste. Snakes have been known to occasionally die from trying to swallow an animal that is too big. Snake digestive acids are unable to digest most plant matter, which passes through the digestive system mostly untouched.
Snakes do not normally prey on people, but there are instances of small children being eaten by large constrictors in the jungle[citation needed]. While some particularly aggressive species exist, most will not attack humans unless startled or injured, preferring instead to avoid contact. The majority of snakes are either non-venomous or possess venom that is not harmful to humans.
As a general rule, snakes eat rodents. There are exceptions to this, such as the natal green snake, which eats insects. Snakes generally pick a few food types to specialise in (for example, royal pythons will generally eat mice and gerbils in the wild).
nicehost-
Snakes feed on different animals. Some very large species can eat mall deer and even crocodiles but most snakes usually prefer smaller pray- mice, rats, frogs, lizards and fish. Besides, snakes have different methods for killing their prey- boas and pythons constrict it and venomous snakes use their fangs to inject powerful venom that will kill the prey quickly and efficiently.
LocCloud-
google...habit of snake.