Poisonous and Non-Poisonous Snakes

General Perception:
    - Snakes are often described as the most innocent animals in the world.
    - They possess the largest number of natural enemies.
    - In certain religions, snakes are worshipped as goddesses.

External Structures:
    - Head: Contains specialized features such as the nostril and eye.
    - Venom Delivery System: Includes the poison gland, the venom canal, and the fangs (specialized teeth for injection).
    - Mouth and Sensory Organs: Features the glottis, regular teeth, and the forked tongue used for sensory perception.
    - Body Structure: Covered in scales; the neck follows the head.
Internal Anatomy:
    - Respiratory System: Includes the trachea, tracheal lung, a large right lung, and a rudimentary (underdeveloped) left lung.
    - Circulatory and Digestive Systems: Includes the heart, liver, stomach, gall bladder, spleen, and intestines (denoted as S).
    - Excretory and Reproductive Systems: Includes the kidneys and testes.

Diversity and Distribution:
- India is home to more than $200$ species of snakes.
- Out of these, only $52$ species are classified as poisonous.
Major Families and Venom Types:
    - Elapidae: Includes the Cobra and Kraits; these possess neurotoxic venom.
    - Viperidae (Vipers): Includes Russell's Vipers, Saw-scaled Vipers, and Pit Vipers; these possess hemotoxic venom.
    - Hydrophidae (Sea Snakes): These possess myotoxic venom.
Relative Toxicity:
- The venom of the Krait (Bungarus) and Russell's viper (Daboia) is significantly more toxic than that of the Indian Cobra (Naja naja).

Overview:
- These four species are responsible for the vast majority ( $70\%$ to $80\%$ ) of snakebite incidents in India.
Species Profiles:
    - Saw-scaled Viper (Echis carinatus): A member of the Viperidae family.
    - Russell's Viper (Daboia russelii): A member of the Viperidae family.
        - Vipers collectively account for hemotoxic and vasculotoxic effects.
    - Common Krait (Bungarus caeruleus): Associated with neurotoxic effects.
    - Indian Cobra (Naja naja): Associated with neurotoxic effects ( $20\%$ to $30\%$ of cases).

Scientific and Biological Characteristics:
    - It is an elapid snake found primarily in the forests ranging from India through Southeast Asia.
    - It is recognized as the world's longest venomous snake.
    - Despite its common name, it is not a member of the genus Naja (the "true cobras").
Physical Dimensions:
- Maximum length reaches between $18.5$ and $18.8\,ft$ ( $5.6$ to $5.7\,m$ ).
Diet and Reputation:
- It preys chiefly on other snakes and occasionally on other vertebrates like lizards and rodents.
- It is considered highly dangerous with a fearsome reputation.

Biological Characteristics:
- Endemic to sub-Saharan Africa.
- Its name is derived from the inky-black color of the interior of its mouth, not its scales.
Physical Dimensions and Speed:
    - It is the longest venomous snake on the African continent.
    - Typical length: $2$ to $3\,m$ ( $6.6$ to $9.8\,ft$ ).
    - Maximum length: $4.3$ to $4.5\,m$ ( $14.1$ to $14.8\,ft$ ).
    - It is among the fastest snakes worldwide, reaching speeds of $11\,km/h$ ( $6.8\,mph$ ) over short distances.

Average Length:
- King Cobra: $9.8$ to $13\,ft$ .
- Black Mamba: $8.2$ to $10\,ft$ .
Maximum Length:
- King Cobra: $18.8\,ft$ .
- Black Mamba: $14.6\,ft$ .
Venom Composition:
- King Cobra: Neurotoxins and Cardiotoxins.
- Black Mamba: Neurotoxins, Cardiotoxins, and Calciseptine.
Geographic Range:
- King Cobra: India, China, Malaysia, Indonesia, and parts of Southeast Asia.
- Black Mamba: South Africa and Eastern Africa.
Dietary Habits:
- King Cobra: Feeds on other snakes.
- Black Mamba: Rats, birds, lizards, and insects.
Venom Quantity:
- King Cobra: $200$ to $500\,mg$ .
- Black Mamba: $50$ to $120\,mg$ .

Head Scales:
- Poisonous: Generally small scales.
- Non-Poisonous: Large scales.
Body Scales:
- Poisonous: Small or moderate.
- Non-Poisonous: Large.
Tail Morphology:
- Poisonous: Compressed tail.
- Non-Poisonous: Tail is not compressed.
Circadian Rhythm:
- Poisonous: Primarily nocturnal.
- Non-Poisonous: Not typically nocturnal.
Bite Evidence:
- Poisonous: Classically leaves $2$ fang marks.
- Non-Poisonous: No fang marks present.

Fang Mark Identification:
- The classic diagnosis involves two puncture wounds.
- Separation distance: $8\,mm$ to $4\,cm$ , varying by species.
Variations in Bite Marks:
- A "side swipe" may result in only a single puncture wound.
- Multiple bites from the same snake can result in numerous fang marks.

Common Worm Snake:
- Small and worm-like; found throughout India.
- Inhabits hills up to an elevation of $1000\,m$ .
Perrotet's Shield-tail Snake:
- Small snake found in the Western Ghats, Nilgiri, and Annamalai hills along India's west coast.
Common Sand Boa:
- Short and thick-bodied; found in plains and low hills of India.
- Nocturnal hunters that emerge after dark.
Red Sand Boa:
- Medium-sized with a very blunt tail; found in drier tracts of the country.
Indian Rock Python:
- Large, thick-bodied snake found in diverse habitats including mangrove forests, arid scrublands, and dense rain forests.
- Located in the eastern Himalayas up to $2000\,m$ elevation.
Vine Snake:
- Medium to large-sized; distributed across India except the northwest and parts of the Ganga plain.
- Prefers low bushes and trees; found up to $2500\,m$ elevation.
Bronze-back Tree Snake:
- Medium-sized and slender; found across India up to $2000\,m$ in the Himalayas.
- Prefers low bushes and thorny trees.
Other Non-Poisonous Examples:
- Calliophis melanurus.
- Gerarda prevostiana (Glossy Marsh Snake).