Carefully read the passage below and answer the multiple choice questions based on what is stated or implied. Answers and explanations will be provided at the end of the test
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Questions 1–11 are based on the following passage.
Passage 1 is adapted from “The Snakes of Europe” by G.A. Boulenger. Originally published in 1913. Passage 2 is adapted from a recent guidebook for “How to Identify a Snake Species.”
When discussing coloration, we have first to distinguish between the color and the markings. The former is very often highly variable among snakes of the same species, to say nothing of the changes which may take place with age or with the condition of the individual snakes, whether before or after exuviation; it is not unusual to find among specimens from the same locality a great range of variation, from greyish-white to brown, or red, or black, as, for instance, in our Common Viper. The latter afford more important characters, and often furnish valuable indications for the distinction of species; but even the disposition of the markings is subject to great individual variations, more likely to mislead than to help the inexperienced student in the discrimination of species.
It is therefore always advisable to resort in the first instance to structural characters for the purpose of specific identification, and to fall back on coloration only as a means of confirmation. If we were to be guided by color and markings alone, how could we believe that an adult four-lined Coluberquatuorlineatus is of the same species as the handsomely spotted Colubersauromates. Yet, if we compare the young of these two snakes we find them to be absolutely identical in their markings, and, in the absence of any structural differences, we are forced to conclude that they only represent two forms of the same species, of which the latter is the more primitive.
It is nevertheless a fact that, with a few exceptions, the markings, however variable they may be, are reducible to certain fundamental patterns to which the innumerable variations may be traced back, and their derivation followed and scientifically explained. Let us consider, for instance, another species of Coluber, highly variable in its markings: C. leopardinus, of which the typical form, so called from having been the first described and named, is not by any means to be regarded as the most primitive.
Identifying snakes has little to do with the myths surrounding poisonous and non-poisonous characteristics and has more to do with body type classification. There are very few tricks that can be used when determining the venom factor, one of which is pupil shape. All snakes with slit-shaped pupils are poisonous. Not all poisonous snakes have slit-shaped pupils. This one certainty is often difficult to ascertain as it requires you to get extremely close to the snake to make your determination. In reality, snake experts use a methodical system to categorize and identify a snake once it has been found.
The first characteristic assessed is body length. Snakes are categorized into three classes: small, medium, and large. Once length is determined, the width of the snake is also examined. If possible, actual dimensions should be gathered. A snake’s head shape can tell a lot about it, but does not necessarily mean anything in regards to venomous or non-venomous. Many vipers have triangular heads, but other snakes can resemble the same shape when they deliberately flatten their heads in aggression or anxiety. Knowing if the snake has a round, long, or oval head will help in identification but is not any proof of venom or lack thereof. Eye color, pupil shape, location on the face, and eye size should all be noted. These three identifiers: body length and width, head shape, and eye characteristics will narrow down the possibilities for species identification.
Color is usually very helpful in determining the type of snake you have located. Many snakes have distinctive patterns. Noting the patterns and the colors is very important. Sometimes the difference between a harmless snake and a deadly viper is one ring of coloration. Blotches usually refer to patterns with no symmetry. These markings are often rectangular with darker edges. If a diamond pattern is noted, color and color pattern should be noted as well. Are there speckles (flecks of color) or spots (large or small defined, solid color circles)? Ring patterns appear like bands around the width of the snake. Stripes are patterns lengthwise down the body. Some snakes are one color on the dorsal side and a different color on the belly. Distinctive markings on the head and neck may be present. Lastly, some snakes have no markings at all and are one, solid color.
Tail characteristics are another guide to identifying a snake. The tail is defined as the length of body stretching beyond the snake’s anus. Tails can end with a rattle. They can be pointed or rounded. Some have specific patterns. Experts are able to use the number and arrangement of scales on a snake to further assist in the identification process. Some snakes are almost identical, and it is these snakes that need the assistance of habitat evaluation. If a snake cannot be identified by appearance alone, the habits of the species will come into play. Some snakes like rocky soil. Some snakes like sand. Some snakes eat only certain animals, or will only be found out at certain times of day. Not all snakes are found everywhere. Having a good, basic knowledge of the local area will help tremendously.
The important thing to remember is that most “quick” identification advice is based loosely on truth. You cannot always be certain of a snake’s venom potential just by the shape of its head, the color of its body, the habitat it lives in, or the color and shape of its eyes.