Heterodon

Common names: hog-nosed snakes, North American hog-nosed snakes.

Heterodon is a genus of colubrids found in North America. Snakes in this genus are stout with upturned snouts, and are perhaps best known for their characteristic threat displays. Three species are currently recognized.

Description

Adults grow to 30-120 cm in length. The body is stout and the head is slightly distinct from the neck. The latter is expandable, the anterior ribs being capable of spreading to flatten that portion of the body, similar to a cobra. The tail is short and the anal scale divided. The dorsal scales are keeled with apical pits in 23-25 rows. The rostral scale is projecting, upturned, recurved and keeled dorsally. There are usually 1-20 accessory scales (azygous) that separate the internasals and the prefrontals. A subocular ring is present with 8-12 ocular scales. There are 7-8 upper labials and 9-13 lower labials. The ventrals number 114-152 and the subcaudals 27-60.

The color pattern is extremely variable. H. nasicus tends to be sandy colored with black and white markings, while H. platirhinos varies from reds, greens, oranges, browns, to black depending on locality. They are sometimes blotched and sometimes solid-colored.

Members of this genus have enlarged maxillary teeth and possess a slightly toxic saliva. In a few cases involving bites from H. nasicus, the symptoms reported have ranged from none at all to mild tingling, swelling and numbness. Nevertheless, they are generally considered to be harmless.

Behavior

When threatened, the hognose snake will flatten its neck and raise its head off the ground, similar to a cobra, and hiss. It may sometimes feign strikes, but is extremely reticent to bite. This behavior has earned the hognose several nicknames, such as "blowing adder," "flathead," "spreading adder," or "hissing adder." If this threat display does not work to deter a would-be predator, the hognose snake will often roll onto its back and play dead with its mouth open and tongue lolling, going as far as to emit a foul musk from the cloaca. Emission of cloacal musk is considerably less likely than in many other species. If the snake is rolled upright while in this state, it will often roll over again as if to insist that it is really dead.

Hognose snakes' most distinguishing characteristic is their upturned snout, which is believed to aid in digging in sandy soils.

Feeding

The bulk of Heterodon diet is made up of rodents, and lizards. H. platirhinos is an exception, and specializes in feeding on toads, having an immunity to the toxins toads secrete.

Captivity

Hognose snakes are frequently found in the exotic pet trade. H. nasicus are often considered to be the easiest to care for, and captive bred stock is easily found. H. platirhinos is commonly found, but their dietary requirements can be a challenge for some keepers.

Species

Species	Authority	Subsp.*	Common name	Geographic range
H. nasicus	Baird & Girard, 1852	2	Western hog-nosed snake	Southeastern Alberta and northwestern Manitoba in Canada, south to southeastern Arizona and Texas in the United States and into northern Mexico. Disjunct populations in Minnesota, Iowa, Illinois, Missouri and Arkansas.
H. platirhinos	Latreille, 1801	0	Eastern hog-nosed snake	United States: eastern-central Minnesota to extreme southern New Hampshire, south to southern Florida and west to eastern Texas and western Kansas.
H. simus	(Linnaeus, 1766)	0	Southern hog-nosed snake	United States: from the coastal plain in southeast North Carolina, south to Lake Okeechobee in Florida and west to southeastern Mississippi.

*) Not including the nominate subspecies (typical form).

References

External links