NATRIX (GRASS SNAKE)

Contents hide

1) Introduction

2) Classification of Natrix (Grass Snake)

3) Geographical distribution

4) Habit and habitat

5) General Characteristics of Natrix (Grass Snake)

6) Ecological Importance

7) Conservation Status

8) Special features

9) Identification

Introduction

The genus Natrix includes non-venomous, semi-aquatic snakes commonly known as grass snakes or water snakes. Found across Europe, parts of Asia, and North Africa, they inhabit wetlands, forests, grasslands, and agricultural areas. Notable species like Natrix natrix (European grass snake) and Natrix tessellata (dice snake) are well adapted to aquatic and terrestrial environments. These snakes play a critical role in maintaining ecological balance and are valued for their contributions to pest control.

Classification of Natrix (Grass 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 :- Colubridae (Facial bones movable. No fang.)
Genus :- Natrix

Geographical distribution

Natrix is widely distributed in U.S.A., Mexico, North Africa and India.

Habit and habitat

It is found in fresh-water, hidden under water vegetation or grasses. It is diurnal, oviparous and feeds on fishes and frogs.

General Characteristics of Natrix (Grass Snake)

Commonly called as Grass Snake or water snake. It is non-poisonous. Piscator is the common Indian water snake.
Body is covered with epidermal scales and chess-board like black spots. Body divided into head, neck, trunk and tail.
Head is distinct and comprises bulging eyes, slit-like mouth and bifid tongue. Head scales are large, called as shields. Belly scales plate-like, while side scales smaller. Bifid tongue protrude between upper and lower jaw.
Both jaws contain teeth but without fangs. Maxillaries horizontal forming most part of upper jaw.
Facial bones movable. Squamosal loosely attached to skull. Tympanum absent.

Ecological Importance

Pest Control: This species feed on amphibians, fish, and small mammals, helping control populations that might otherwise become invasive or cause ecological imbalance.
Prey for Other Animals:
- Grass snakes are an essential part of the food web, serving as prey for birds of prey, larger snakes, and mammals such as foxes.
Aquatic Ecosystem Balance:
- By preying on fish and amphibians, Natrix species help regulate aquatic ecosystems.
Indicator of Ecosystem Health: The presence of grass snakes indicates a healthy, biodiverse environment with clean water bodies.

Conservation Status

Conservation Status: Most species of Natrix are classified as Least Concern by the IUCN. Local populations may face threats due to habitat degradation.
Threats:
- Habitat loss due to urbanization, agriculture, and pollution of wetlands.
- Persecution stemming from fear and misunderstanding of snakes.
- Declines in amphibian populations, their primary prey, due to environmental changes.
Conservation Measures:
- Protection of wetland habitats and preservation of clean water sources.
- Awareness campaigns to reduce human-snake conflicts.
- Legal protections in regions where Natrix species are under threat.

Special features

Aquatic Adaptations: Grass snakes are excellent swimmers, often found near water bodies where they hunt for prey.
Defense Mechanisms: When threatened, they emit a foul-smelling substance or play dead to deter predators.
Non-Venomous Nature: Harmless to humans, they rely on speed and agility to avoid predators.
Coloration: Typically green, olive, or brown with distinctive markings like a yellow or white collar behind the head, aiding in camouflage.
Breeding and Eggs: Grass snakes are oviparous, laying eggs in warm, decaying vegetation that acts as a natural incubator