The sea snakes, which may have evolved on the Australian continent, are concentrated in coastal waters of Australasia and Southeast Asia. The 270 or so elapid species vary greatly in size, color, and markings, but their basic anatomy, shape, and arrangement of scales are much like those of colubrids, a typically harmless group of snakes. The underbelly of the snake has a single row of wide scales. The head is small with nine large plates on the crown. The pupils are round.
Many elapids raise the front part of the body as a threat display.
The defining feature of Elapidae is a pair of short, immovable fangs in the front portion of the upper jaw. The fangs have a hollow center and holes at the base and near the tip. The snake bites with a downward stab, simultaneously squeezing out venom. In the spitting cobras, the holes for venom discharge are round and face outward. When threatened these cobras spray two jets of venom at the eyes of their opponent.