The weird, wondrous world of seahorses

They look like a mix of other animals, the males give birth, and we still have much to learn about them. Now these unique fish are threatened.

A pair of Western spiny seahorses (male at  left) from Australia intertwine tails for stability. Seahorses inhabit coastal waters nearly worldwide, clinging to seagrasses, corals, and sponges. Their populations are being squeezed by overfishing and habitat loss.
Hippocampus angustus, Seahorse World, Beauty Point, Tasmania

Miguel Correia pointed at the seafloor. I stared and shook my head. He jabbed a gloved finger at the spot. I swam closer and stared harder. Sand. Algae. Rocks. A spiral of sea cucumber poop. I exhaled a swarm of bubbles in frustration.

And then, suddenly, there it was, tucked into the seaweed right where I’d been looking: a three-inch-tall, long-snouted seahorse, Hippocampus guttulatus, muddied yellow with a smattering of dark freckles and a mane of skin filaments. Later that dive I spotted (also with help) its short-snouted cousin, Hippocampus hippocampus, the other seahorse native to this coastal lagoon in Portugal called Ria Formosa.

Every continent but Antarctica has varieties of these fabled fish in its coastal waters. Worldwide, scientists recognize 46 species, the smallest no bigger than a lima bean, the largest the size of a baseball glove. And that number is likely to rise: Four new species were named in just the past decade.

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