The Horse of the Sea

The seahorse is a small marine fish whose upright posture, horse-like head and curling tail made it seem, to the ancients, a creature of two worlds. Greek and Roman art gave the sea-god Poseidon (the Roman Neptune) a chariot drawn across the waves by the hippocampus, a fabulous beast with the foreparts of a horse and the tail of a fish, of which the little living seahorse was taken to be the model or the young; hippocampi carry the sea-gods and their retinue through countless mosaics and fountains. The seahorse thus stood, in the classical imagination, for the power of the sea harnessed and ridden.

For all their mythic role pulling the sea-god's chariot, real seahorses are among the weakest swimmers of any fish, propelled by a small dorsal fin beating up to thirty-five times a second yet still easily exhausted by strong currents, which is why they anchor themselves to seagrass and coral with their prehensile tails rather than swim freely; some paired seahorses perform a daily greeting ritual of changing colour and a brief synchronised dance, behaviour documented by researchers including Amanda Vincent, whose Project Seahorse has driven much of the modern conservation science on the genus.