They mate for life and perform a twirling dance of courtship every morning, a prelude to one of the most bizarre forms of reproduction in the animal world: male pregnancy.
Sea horses might inhabit a mythical kingdom of strange beasts if they did not frequent the seas off South America, Africa, Asia and Australia.
And the fish with the head of a horse and tail of a dragon even survives in Hong Kong waters.
This is ironic since Hong Kong today is a leading entrepot for the seahorse trade, fuelled by traditional Chinese medicine, which has decimated populations throughout Asia.
Divers often spot mature sea horses in shallows near coral or sea grass, and Hong Kong University doctorate student Andy Cornish said they occurred across the territory from Lamma to Mirs Bay.
Curling their tails around a perch of sea grass or one of Hong Kong's shark nets, they prey on passing fish, plankton or crustaceans.
'Shark nets are absolutely perfect for sea horses, they have got to have something to hold on to,' he said.
The 35 species of sea horses identified worldwide are threatened by traditional Chinese medicine, where they are used for ailments including asthma, heart and kidney disease and as an aphrodisiac.
Until the 1970s sea horses were commercially harvested in Hong Kong and today sport fishermen continue the tradition, netting them for fun.
But this hobby could represent a big threat to the population along with reclamation and pollution, said Mr Cornish.
'Anywhere else where they have been collected they have been decimated.' Sea horses are not protected by law - except in marine parks and reserves - and are thus at risk of exploitation.