CROTALUS (RATTLE SNAKE)

Introduction

Crotalus is a genus of venomous pit vipers commonly known as rattlesnakes, found mainly in North and South America. These snakes are easily recognized by the keratin-filled rattle at the tip of their tails, which they vibrate as a warning to predators. Crotalus species possess heat-sensing pits, allowing them to detect warm-blooded prey with precision. Their venom is a potent mix of hemotoxins and neurotoxins, used for both defense and immobilizing prey. Despite their reputation, rattlesnakes play a vital ecological role by controlling rodent populations and maintaining balance within their habitats.

Classification of Crotalus (Rattle Snake)

• Phylum :- Chordata (Dorsal tubular nerve cord, notochord and gill-slits present.)
• Group :- Craniata (Definite head, Cranium with brain present.)
• Sub phylum :- Vertebrata (Vertebral column present.)
• Division :- Gnathostomata (Jaws and paired appendages present.)
• Super Class :- Tetrapoda (Paired limbs, lungs, cornified skin and bony skeleton.)
• Class :- Reptilia (Scaly vertebrates. Right and left aortic arches present. Single condyle. Pulmonary respiration. Embryo with amnion and allantois.)
• Sub Class :- Diapsida (Skull with two temporal openings separated by post-orbital and squamosal.)
• Order :- Squamata (Lizards and snakes with horny epidermal scales or shields. Quadrate bone movable. Vertebrae procoelous. Anal opening transverse.. Vertebrae amphicentrous.)
• Sub-order :- Ophidia (Snakes. Limbs, feet, ear openings sternum and urinary bladder absent. Mandibles jointed anteriorly by ligament. Tongue slender, bifid and protrusible. Left lung reduced.)
• Family :-  Viperinae (Paired erectile fangs in front of upper jaw.)
• Genus :- Crotalus

Geographical distribution

• Crotalus is found in U.S.A. and Mexico, North America and contains Crotalus horridus, a common rattle snake of U.S.A. Crotalus confluentus is found in western America. About 40 species and varieties are found in Western Hemisphere and approximately 20 in U.S.A.

Habit and habitat

• It is adapted for terrestrial life. During winter season it hibernates under the ground. The snake is carnivorous, nocturnal and feeds on small mammals.

General Characteristics of Crotalus (Rattle Snake)

• Commonly called as Rattle snake.
• Body is elegantly elongated, measuring 2 to 3 meters in length. Body divided into head, neck, trunk and tail. Head contains nostrils, eyes, mouth and head scales.
• General surface greyish brown with dark bands and handsome pigmentation pattern.
• Head is triangular in shape, distinct from the neck having small nostrils and ventral mouth. Upper side of head has small scales.
• Eyes are small, without eyelids, and a sensory pit is present between eye and nostril.
• There are two erectile fangs in front of jaw, one on each maxillary bone and folded backwards when not in use.
• Tongue bifid and protrusible. Two pairs of inter nasals present.

Ecological Importance of Crotalus (Rattle Snake)

• Population Control:
  • Crotalus species prey on small mammals like rodents, helping to regulate populations and prevent crop damage or the spread of diseases such as hantavirus and plague.
• Food Web Dynamics:
  • As both predators and prey, rattlesnakes contribute to the balance of their ecosystems. They are preyed upon by birds of prey, larger mammals, and other snakes.
• Ecosystem Engineering:
  • Abandoned rattlesnake burrows provide shelter for other animals, enhancing biodiversity in their habitats.
• Indicator Species: Rattlesnakes’ presence indicates a healthy, balanced ecosystem with adequate prey and minimal human disturbance.

Conservation Status of Crotalus (Rattle Snake)

1. The conservation status of Crotalus species varies. Some, like the timber rattlesnake (Crotalus horridus), are listed as Near Threatened, while others are not currently at risk.
2. Threats:
   • Habitat destruction due to urbanization, agriculture, and deforestation.
   • Persecution and collection for the exotic pet trade.
   • Climate change altering their habitats and prey availability.
3. Conservation Measures:
   • Protecting natural habitats and restricting land development in sensitive areas.
   • Public education to reduce human-snake conflicts and discourage unnecessary killings.

Special features

• The snake is immediately characterized by the presence of a rattle at the end of the tail. Rattle is derived from moulting epidermis consisting of 10-12 hollow segments. During fast locomotion, tail is vibrated and rattle produces characteristic rattling sound which warns the intruder.
• It is a deadly poisonous snake and is viviparous.
• Rattle Mechanism: Made of keratin segments at the tail’s end, the rattle produces a characteristic sound to warn predators or threats.
• Pit Organs: Heat-sensitive pits on their heads allow them to detect warm-blooded prey even in complete darkness.
• Venom Potency: Crotalus venom contains hemotoxins that immobilize prey and aid in digestion, while also serving as a defense mechanism.
• Camouflage: Their color patterns blend with their surroundings, offering protection against predators and facilitating ambush hunting.
• Behavioral Adaptations: They are generally shy and reclusive, using their rattle to avoid confrontations rather than engage in aggression.

Identification

• Since this snake contains rattle in tail and above features, hence it is Crotalus.