Elapids are generally slender, highly agile snakes with a colubrid-like head that is not very distinct from the neck and bears large, colubrid-like scales or scutes. Elapids lack the lo-real scute that separates the nasal scute from the preorbital scutes (most nonvenomous colubrid snakes have this scute). Because the fangs are short, the mouth does not have to open wide when the snake strikes. The length of these snakes varies from 7 in (18 cm) (the rare Fijian, Ogmodon vitianus) to more than 200 in (5 m) (king cobra, Ophiophagus hannah). The body often has stripes that may be very colorful. Many cobras flatten when excited, and cobras are famous for the ability to spread their neck ribs to form a hood.
The coral snakes of the Americas can be unicolored (no bands), but most species are famous for having a bright series of alternating color bands. The snakes may be bicolored, tri-colored, or even quadricolored. The bands serve as a warning to potential predators. Also famous is the diverse radiation of nonvenomous snake mimics of the coral snakes. Many species of nonvenomous snakes that live in the same regions as coral snakes have evolved coloration almost identical to that of coral snakes. It has been estimated that 18% of all snakes found in the Americas are coral snake mimics. There are twice the number of mimics as there are coral snake species.
Seasnakes have evolved many adaptations, from the partially marine existence of the sea kraits (Laticauda) to the fully marine existence of the seasnakes. The nostrils of all seasnakes have valves that form a tight seal around the mouth when the snake dives. Fully marine seasnakes move sinusoidally as do land snakes, but they propel themselves through the water with a paddle-shaped tail rather than by grabbing the substrate with wide belly scales as land snakes do. The belly scales of fully marine seasnakes are almost the same size as their other body scales.
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