Crotalus tigris
Encyclopedia
- Common names: tiger rattlesnake, tiger rattler.
Crotalus tigris is a venomous
Venomous snake
"Poisonous snake" redirects here. For true poisonous snakes, see Rhabdophis.Venomous snakes are snakes which have venom glands and specialized teeth for the injection of venom...
pit viper
Crotalinae
The Crotalinae, commonly known as "pit vipers" or crotaline snakes, are a subfamily of venomous vipers found in Asia and the Americas. They are distinguished by the presence of a heat-sensing pit organ located between the eye and the nostril on either side of the head...
species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
found in the southwestern United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
and northwestern Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...
. No subspecies are currently recognized. The specific name is Latin for tiger and is an allusion to many narrow dorsal crossbands that create a pattern of vertical stripes.
Description
The color pattern consists of a gray, lavender, blue-gray, pink or buff ground color that usually turns to pink, pale orange or cream on the sides. This is overlaid with a series of 35-52 crossbands that are dark gray or brown in color and consist mainly of heavy punctations. These crossbands have vague borders and are wider dorsally than latterally. Also middorsally, the crossbands become wider than the spaces that separate them. Posteriorly, the crossbands also become darker and more clearly defined. The markings on the head are mostly vague and irregular, although towards the rear, a few dark markings may be arranged as paired occipital blotches and upper temporal streaks.
Geographic range
C. tigris is found in the southwestern United StatesUnited States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
in south-central Arizona
Arizona
Arizona ; is a state located in the southwestern region of the United States. It is also part of the western United States and the mountain west. The capital and largest city is Phoenix...
, in northwestern Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...
in Sonora
Sonora
Sonora officially Estado Libre y Soberano de Sonora is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is divided into 72 municipalities; the capital city is Hermosillo....
, and on Isla Tiburón
Tiburón Island
Tiburón Island is both the largest island in the Gulf of California and the largest island in Mexico, with an area of . It was made a nature reserve in 1963 by President Adolfo López Mateos. Tiburón is Spanish for shark. The etymology of the Seri name is unknown...
in the Gulf of California
Gulf of California
The Gulf of California is a body of water that separates the Baja California Peninsula from the Mexican mainland...
. The type locality is described as "Sierra Verde and Pozo Verde". The latter is a spring located on the Sonora
Sonora
Sonora officially Estado Libre y Soberano de Sonora is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is divided into 72 municipalities; the capital city is Hermosillo....
side of the US-Mexico border, near Sasabe. According to Stejneger (1893), this spring is on the western slope of the southern Sierra Verde, which is also known as the Sierra del Pozo Verde.
Conservation status
This species is classified as Least Concern (LC) on the IUCNWorld Conservation Union
The International Union for Conservation of Nature and Natural Resources is an international organization dedicated to finding "pragmatic solutions to our most pressing environment and development challenges." The organization publishes the IUCN Red List, compiling information from a network of...
Red List of Threatened Species
IUCN Red List
The IUCN Red List of Threatened Species , founded in 1963, is the world's most comprehensive inventory of the global conservation status of biological species. The International Union for Conservation of Nature is the world's main authority on the conservation status of species...
(v3.1, 2001). Species are listed as such due to their wide distribution, presumed large population, or because it is unlikely to be declining fast enough to qualify for listing in a more threatened category. The population trend was stable when assessed in 2007.
Venom
Although it has a comparatively low venom yield, according to Weinstein and Smith (1990), its toxicity is considered to be the highest of all rattlesnake venoms. It has a high neurotoxicNeurotoxin
A neurotoxin is a toxin that acts specifically on nerve cells , usually by interacting with membrane proteins such as ion channels. Some sources are more general, and define the effect of neurotoxins as occurring at nerve tissue...
fraction that is antigen
Antigen
An antigen is a foreign molecule that, when introduced into the body, triggers the production of an antibody by the immune system. The immune system will then kill or neutralize the antigen that is recognized as a foreign and potentially harmful invader. These invaders can be molecules such as...
ically related to Mojave toxin (see Crotalus scutulatus
Crotalus scutulatus
Crotalus scutulatus is a venomous pitviper species found in the deserts of the southwestern United States and central Mexico. It is perhaps best known for its potent neurotoxic venom...
, venom A), and includes another component that is immunologically identical to crotamine, which is a myotoxin
Myotoxin
Myotoxins are small, basic peptides found in snake venoms, such as in that of certain rattlesnakes. This involves a non-enzymatic mechanism that leads to severe muscle necrosis...
also found in tropical rattlesnakes (see Crotalus durissus). There is low, but significant protease
Protease
A protease is any enzyme that conducts proteolysis, that is, begins protein catabolism by hydrolysis of the peptide bonds that link amino acids together in the polypeptide chain forming the protein....
activity in the venom, although there does not seem to be any hemolytic activity.
Brown (1973) lists an average venom yield of 11 mg (dried venom) and an value of 0.6 mg/kg IP for toxicity.
Essentially no information available for bite symptoms. Despite the low venom yield, a bite by this or any rattlesnake should be considered a life-threatening medical emergency.
External links
- Crotalus tigris images at California Reptiles and Amphibians. Accessed 16 May 2007.
- Crotalus tigris at Reptiles and Amphibians of Arizona. Accessed 16 May 2007.