Grass snake (Natrix natrix)

The grass snake is presented in scientific and natural‑history terms rather than as a mythic origin narrative in the supplied sources. Taxonomically it has long been recognised within Linnaean classification as Natrix natrix; recent genetic and taxonomic work noted in the sources has led to the elevation or separation of some former subspecies (for example Natrix helvetica recognized as a distinct species in 2017, and Natrix astreptophora the Iberian grass snake). The documentary focus in the materials provided is on distribution, ecology and systematics (including historic and contemporary reclassifications) rather than any cosmological or creation story: the species is situated within modern herpetology and citizen‑science recordkeeping rather than a folkloric origin framework.

Adults are typically dark green or brown with a characteristic yellow or white collar (neck ring) bordered with darker markings; underparts are whitish with irregular black markings. Size can reach around 1 m (3 ft 3 in) or more; hatchlings are reported at about 18 cm (7 in). The pupil is round. Colouration shows regional variation—tones range from olive to grey or black, with darker colours more prevalent in colder regions. Defensive displays include raising the forebody and flattening the head and neck to resemble a cobra; otherwise the species’ distinctive neck collar and semi‑aquatic, slightly keeled body scale appearance are diagnostic in field guides and observational notes.

Ecologically, grass snakes are semi‑aquatic strong swimmers commonly found at pond edges, open woodland margins and in compost heaps where eggs are often deposited. Diet is centered on amphibians (common frog and toad are primary prey) though other sources note occasional consumption of ants, insect larvae, small rodents, eggs and invertebrates. They actively forage for live prey and consume prey alive without constriction. Reproductive behaviour includes spring emergence (males often appearing first), mating in early spring (April or earlier in warm conditions), and egg‑laying in warm, humid sites such as compost or rotting vegetation in June–July; clutches commonly number 8–40 eggs and hatch after roughly ten weeks under appropriate thermal and moisture conditions. Seasonal physiology includes ecdysis (moulting) once or more per active season, periodic reduced activity when 'in blue' (obscured eyes during shedding), and overwintering in subterranean refuges to avoid freezing. Defensive behaviours documented in the sources include hissing and striking without opening the mouth, secretion of a malodorous garlic‑smelling fluid from cloacal glands, thanatosis (playing dead) sometimes accompanied by autohaemorrhage from the mouth or nose, regurgitation of stomach contents when handled, and rare, non‑venomous bites.