Don’t let their unusual shape fool you—seahorses are actually fish! They’re most closely related to pipefishes and seadragons (maybe you can see the resemblance in their long noses). Unlike most other fish, seahorses swim upright. They are generally pretty small and range from about the size of a thumbnail to more than a foot long. The genus Hippocampus includes 47 species of seahorses, and almost 1/3 of those were discovered within the last decade—there are probably more that haven’t been discovered!

It can be difficult to spot seahorses in the wild. In addition to their generally small size, they are experts in camouflage, and many of them have similar patterns to their habitat, allowing them to seamlessly blend into coral or seagrass. This helps them both hide from predators and sneak up on prey. Unfortunately, seahorses can’t always hide, and one of the largest threats to their population is illegal capture by humans for use in traditional medicines and home aquariums.