I'm currently reading the book, Eating Animals by Jonathan Safran Foer and learned the following about these amazing little creatures:
The sea horse can often die from exhaustion if stuck in a current or getting caught in a wave because their tiny fins have to beat much like a hummingbird to swim. Thirty five species of seahorses are actually in danger of extinction due to being a casualty of seafood production (mostly shrimp).
Because seahorses are so easily exhausted, they usually anchor their tail in seaweed or link to each other to prevent from being swept away.
The most amazing thing about seahorses (besides that the male gives birth) is that they mate for life and are monogamous.
P.s. If you haven't read Foer's book, you should. It's Amazing.