Overview
The Dice Snake (Natrix tessellata), widely known across European herpetology as the Tessellated Water Snake, is an exceptionally aquatic, harmless, and agile natricine colubrid native to the clean rivers, rocky lakes, and coastal bays of central and southern Europe, the Middle East, and Central Asia. Closely related to the Grass Snake, this elegant water serpent gets its common name from the striking, chess-board or die-like (tessellated) pattern of small, square-shaped dark blotches arranged in alternating rows across its greyish-green, olive-tan, or bronze body.
Unlike its frog-hunting relative, Natrix tessellata is a hyper-specialized underwater piscivore, spending hours completely submerged in rapid currents and deep lake bottoms stalking benthic bottom fishes such as gobies and stone loaches. Equipped with nostrils and eyes situated high on its snout for surface snorkeling, it can hold its breath for over an hour beneath underwater boulders. Completely non-venomous, when captured it stages the same legendary theatrical performance of playing dead (thanatosis) and exuding putrid anal musk, making it an iconic and harmless jewel of Eurasian freshwater ecosystems.
AT A GLANCE
- Common Name: Dice Snake
- Scientific Name: Natrix tessellata
- Category: Reptiles
- Subcategory: Snakes
- Size: Total length 75–100 cm (30–39 in), exceptionally reaching 130–150 cm (51–59 in)
- Weight: 150–400 g (5.3–14.1 oz); large females can exceed 550 g
- Lifespan: 12–18 years in the wild; over 20 years in captivity
- Diet: Strictly carnivorous piscivore feeding almost exclusively on freshwater and marine bottom fishes (gobies, loaches, sculpins, cyprinids), supplemented by occasional tadpoles
- Habitat: Fast-flowing rocky rivers, clear freshwater lakes, gravel-bed streams, coastal lagoons, and brackish sea shores (Caspian and Black Seas)
- Range: Central, southern, and eastern Europe across western and central Asia to northwestern China (Xinjiang) and Pakistan, and south to Egypt and the Levant
- Conservation Status: Least Concern
Biology and Physical Characteristics
Morphologically, Natrix tessellata is an evolutionary masterpiece of aquatic specialization. Its head is narrower, more pointed, and more triangular than that of the grass snake, allowing it to probe between tight submerged riverbed stones. Its eyes and nostrils are positioned somewhat dorsally, enabling the snake to breathe and scan the shoreline while keeping ninety-nine percent of its body submerged under water. Its dorsal scales are heavily keeled, providing superior water traction during vigorous serpentine swimming and preventing slick, mucus-coated fish from squirming free from its coils. It lacks venom fangs, possessing sharp, backward-pointing aglyphous teeth that grip struggling fish securely. Its lower jaw features flexible elastic ligaments that allow it to swallow spiny bottom-dwelling fish (such as bullheads and sculpins) whole while underwater.
Behavior and Ecology
Behaviorally, dice snakes are strictly diurnal, spending warm morning hours basking on rocky riverbanks, stone riprap, or low overhanging willow branches. When warm, they dive into the water to hunt, actively searching river bottoms or waiting in ambush beneath sunken logs for passing gobies. Remarkably, dice snakes frequently swallow captured fish entirely underwater, only surfacing if the prey is exceptionally large and violently thrashing. When threatened by herons, predatory fish, or humans on land, the dice snake rarely attempts to strike; instead, it rolls onto its back, flattens its body into complete limpness, allows its tongue to hang out of an open, bleeding mouth, and discharges a foul, nauseating fluid from its anal scent glands that smells like rotting fish. Reproduction is oviparous: in July, females lay clutches of 10 to 30 white, oval eggs in warm, moist gravel banks, rotting driftwood piles, or compost, which hatch after roughly six weeks of incubation.
Conservation and Human Impact
The Dice Snake is classified globally as Least Concern on the IUCN Red List of Threatened Species, supported by its immense geographic range across Eurasia and abundant populations in eastern Europe and the Caspian basin. However, in western and central Europe—particularly in Germany, Switzerland, and northern Italy—isolated populations have suffered severe declines due to river channelization, dam construction that alters natural flow rates, destruction of gravel basking beaches, and heavy water pollution that depletes native benthic fish stocks. The species is legally protected under Annex IV of the EU Habitats Directive, requiring member states to preserve natural riverine corridors.
Interesting Factoid
The dice snake can hold its breath underwater for over an hour while hunting on riverbeds—and when caught, it plays dead so convincingly that it actually bleeds from its gums and oozes a foul scent that smells like rotten fish to fool predators!