Snake Identification Characteristics
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In the following paragraphs, I describe a number of physical characteristics which can be used to identify a snake species. These characteristics, listed roughly in order of ease of observation, are length, body shape, head & neck shape, color, pattern, scale texture, eye pupil shape, tail scales, and anal plate division. The list is not exhaustive, for instance, geographic location and habitat also provide important clues. Although no single characteristic is sufficient to make an identification, a reasonably accurate identification can usually be made from length, body shape, head & neck shape, color and pattern. Color and pattern can be confusing, and some species have several alternate colors or patterns. Also, color and pattern usually relates independently to the back & sides and the belly. The remaining characteristics can be very useful as confirming or distinguishing characteristics if greater access to the snake is available.
Each characteristic is discussed below with suggested categories to aid in identification. Use the hyperlinks to view examples of the characteristics and categories.
Length is probably the first characteristic one observes when seeing a snake. Adult snakes of species indigenous to the United States range in length generally from 8 inches to 6 feet. There are a few species in which individual specimens may grow to lengths of 8 or 9 feet, but such specimens are very rare. Most newborn snake species range in length from 3 to 17 inches.
Accurately judging the length of a snake is difficult. They most often move with their bodies in curves, and movement itself often makes it difficult to focus on the entire snake. Even measuring the length of a live snake is difficult. These are reasons why I usually describe a snake using an approximate length. When attempting to judge the length of a snake, I suggest trying to view it relative to a nearby object which you can measure or make a good length judgement.
For adult snakes, I suggest describing their length as:
small: 6 to 18 inches,
medium: 19 to 36 inches, or
large: > 3 feet
These categories are based on typical adult sizes. Immature specimens of larger snakes obviously fall into the lower categories. The medium category is most problematic since immature specimens will fall into the small category and exceptionally large specimens may fall into the large category. However, remember these length descriptions are not intended to be precise; rather, you should make a general impressionistic categorization. If the snake is 4 feet or longer, it almost certainly falls into the large category. If the snake is only 3 to 5 inches long, it is probably an immature species in the small category.
return to topBody Shape is another overall characteristic that helps distinguish snake species. Snakes of any length category may range from slender to stout. Body shape is a characteristic which should be judged from the overall impression. Snake body girths normally change smoothly from head to tail. Since snakes swallow their prey whole, their bodies may be misshapened following eating of large prey. Body extension from food is usually exhibited as a lump in the body rather than a change in the overall shape. A more misleading change in normal body shape will be effected in gravid females. Depending upon the species, snakes may either lay eggs or give live birth. A normally slender or typical-bodied snake may appear stout when gravid. Often with such gravid snakes, the girth will be extended non-uniformly, showing a series of lumps spread along the ending half of the body. In other cases, the observer may not be able to distinguish the body shape from a normally stout shape.
I suggest three categories of body shape:
typical, or
Deciding between these body shapes is very subjective. I suggest classifying a snake as typical body shape if the observer is uncertain as to it being slender or stout.
return to topHead & Neck Shape can be used to narrow the list of potential species. Folklore says that snakes with heads shaped like arrowhead are venomous. While it is true that pit vipers (which include all our venomous snakes except the Coral Snake) do have heads suggestive of arrowheads, there are many nonvenomous species which have broad heads are also suggestive of the arrowhead shape. Also, many snakes assume a defensive posture in which they flatten their heads, making them appear broader and more arrowhead-like. Therefore, I believe it is more useful to categorize head shape in only three broad categories.
no neck - many snakes have small heads relative to their body diameter. In these snakes there is very little difference between the diameter of the head and the body;
medium headed - for these snakes the head is distinguishable from the body but not excessively so. In these snakes the head length (in the non-aroused state) is noticeably longer than its width.
broad headed - for these snakes the diameter of the neck is noticeably smaller that that of the head and the head's length is only a little longer than its width.
Deciding between these head shapes is also very subjective. I suggest classifying a snake as medium head shape if the observer is uncertain as to it being no neck or broad.
return to topColoration and Pattern are the most specific characteristics helping to identify a species. However, they can be the most difficult characteristics to describe. Also, most snakes have different colors and patterns on their backs and bellies.
Color is a frequently used descriptor in much of our lives. As such observers usually can use their commonly used terms for color. Some snakes have many different colors and shades, especially on their backs. I suggest the observer describe the snake in terms of the most dominant colors and shades only.
return to topPattern is formed by the distribution of color and shade on the snake's body. Pattern is the most confusing characteristics to describe. For this reason, it is important to use defined terms when describing pattern. Just as some people can see faces in clouds, people can see many different patterns in snakes
For dorsum pattern, I suggest the use of seven descriptor categories:
no pattern - the snake appears to have a uniform color or to be basically one color with only faint or sparse patterning from other colors;
colored head - for some snake speices, the color/pattern of the head may be in stark contrast to that of the body; in such cases the head of the snake (usually excluding the chin) is often distinct color or shade from the rest of the body; usually a dark color; in other cases there may be a ring or spot of contrasting color immediately behind the head; there are three indigenous SC species which I would place in to colored head category for purpose of primary identification: the Ringneck Snake (both the Northern and Southern subspecies), the Southeastern Crown Snake and the Pine Woods Snake; the Brown Snakes (including the Redbelly Snakes) also, but to a lesser degree, have colored heads which can be useful in identification, especially for neonates;
linear multicolor - the snake's color changes (with area of blending) from head to tail (usually there are only two colors; there may be minor patterning); (there is only one indigenous SC species with linear multicolor of the dorsum: the Eastern Coachwhip);
spotted - spots (usually with rounded edges, may be small) of distinct color or shade are arranged on the body in a linear fashion (usually in one or two rows, but may be more random);
banded - bands are areas of distinct color or shade which tend to run around the girth of the body (that is, perpendicular to the length of the body) and are distributed along the length of the body; bands may be of nearly uniform width (rings) or of varying width; bands may be continuous across the back or may be broken at the sides, and the side portions may not be aligned with the back portion; bands may be viewed as adjacent and alternating or as occurring against a background color.
blotched - blotches are a special type of band which occur in many species; blotches are bands occurring against a background where the side portions of the bands are absent or disjunct and greatly reduced; most blotches have rounded edges, but some may have nearly straight edges (for example, a diamond shape);
striped - stripes are lines of distinct color or shade which run in the direction of the length of the body.
For belly pattern, I suggest the use of seven descriptor categories:
no pattern - the snake appears to have a uniform color or to be basically one color with only faint or sparse patterning from other colors;
linear multicolor - the snake's belly color changes (with area of blending) from head to tail (usually there are only two colors; there may be minor patterning);
spotted - spots or blotches of color distributed linearly or randomly;
banded - bands are areas of distinct color or shade which tend to run the width of the belly; belly bands usually connect with dorsal bands;
striped - stripes are lines of distinct color or shade which run in the direction of the length of the belly.
return to topScale Texture refers to the shape of the individual scales on the dorsum of the snake. The surface of a smooth scale is nearly flat or slightly rounded. A keeled scale has a pinched ridge in the center. To a great extent, the amount of keeling of the scales is related to the shine of the scales. Smooth scales are shiny and strongly keeled scales are usually not.
smooth - snakes with smooth scales appear slick and shiny, as if they are made of plastic.
weakly keeled - the weak keeling may not be obvious; snakes with weakly keeled scales may appear shiny or not, depending upon the species; Rat snakes (Black, Yellow, Integrade, and Corn) appear shiny. Copperheads and Cottonmouths have little or no shine.
keeled - snakes with keeled scales appear rough and usually have little or no shine (the Glossy Crayfish Snake is the only indigenous SC species with keeled scales which appear very shiny).
return to topEye Pupil Shape (for snakes indigenous to SC and the Southeast) can be used as a reliable indicator that the snake is a pit viper (venomous).
elliptical - all pit vipers have eye pupils with a vertical, elliptical shape, much like a cat's eye.
round - all other indigenous snakes in SC and the Southeast have round pupils, like a person's eye. All of these indigenous snakes with round pupils are nonvenomous, except the highly venomous Coral Snake.
return to topUndertail Scaling - all snakes have a single row of scales along their bellies. Contrary to what many people believe, snakes have short tails. A snake's tail begins at the anal vent.
single - the pit vipers (venomous) have a single row of scales under the tail beginning at the vent. Near the end of the tail, the single row will change into a double row.
double - all other indigenous snakes in SC and the Southeast have a double row of scales running the length of the underneath of the tail. All of these indigenous snakes with double rows of scales underneath the entire tail length are nonvenomous, except the highly venomous Coral Snake.
return to topAnal Plate division can be used as an confirming characteristic in identification. Unlike eye pupil shape and undertail scaling, the anal plate scaling can not be used to identify a venomous snake. The anal plate is the scale covering the anal vent. It occurs at the end of the single belly scales which all snakes have.
single - the anal plate may be single (undivided), or
split (double).
Although all the pit vipers have single anal plates, there are many nonvenomous species with single plates also.
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August 11, 2000© 2000. Edwin Eugene Ott
