Snake

Several snake species including boa constrictors and copperheads are capable of facultative parthenogenesis — producing offspring without fertilization. Female snakes can do this when isolated, essentially cloning themselves, though offspring have reduced genetic diversity.

Each time a rattlesnake sheds its skin, a new hollow keratin segment is added to the rattle. The segments interlock but are not attached, so they knock together to produce the distinctive sound. A new snake grows one segment per shed.

Tetracheilostoma carlae, the Barbados threadsnake, is the world's smallest known snake at just 10 cm long and as thin as a strand of spaghetti. It was only discovered in 2008 and feeds exclusively on termite and ant larvae.

China's earthquake bureau has monitored snake behavior since 2006, finding that snakes leave their burrows and behave erratically up to five days before a quake. They can detect seismic vibrations at distances of 120 km.

The boomslang of sub-Saharan Africa has hemotoxic venom that destroys red blood cells and prevents clotting, causing victims to bleed from every orifice. Symptoms may not appear for 24 hours, delaying treatment and making it uniquely dangerous.

African egg-eating snakes are specialised to consume only eggs. They swallow the egg whole, crack it with bony projections from their spine, absorb the contents, and then neatly regurgitate the crushed shell — an impressive feat for an animal with no teeth.

Snakes lack movable eyelids. Instead, each eye is covered by a single transparent scale called a spectacle or brille. Because they cannot close their eyes, they sleep with eyes permanently open, making it difficult to tell if a snake is asleep.

Spitting cobras can eject twin streams of venom up to 2.5 meters, consistently targeting the eyes of threats. The venom causes intense pain and potential blindness. Studies found they aim with over 90% accuracy even at moving targets.

Large constrictors like pythons and anacondas can survive 12–18 months without food after a large meal. They slow their metabolism by up to 70% and even begin shrinking their own organs to conserve energy during long fasts.

The reticulated python of Southeast Asia holds the record for the longest verified snake, with specimens confirmed at over 7.5 meters. They are powerful constrictors and have occasionally been documented consuming large prey including deer and pigs.