Seahorses are in the Animal Kingdom and in the phylum Chordata, which means they have backbones. They are teleosts – which means they are in fact fish! Seahorses and all of their related cousins are in the family Syngnathidae, named because they have fused jaws and no teeth. All seahorses are in the genus Hippocampus. Hippocampus comes from the Greek for horse and sea monster. In fact, sailors used to get tattoos of seahorses because they thought it would help protect them from drowning.
There are 46 known species of seahorses around the globe. They live in shallow coastal seas in temperate and tropical regions. Seahorses can typically be found in seagrass meadows, coral reefs, under mangrove trees in the prop roots, and sometimes attached to sargassum floating in the open ocean. In the US along the Atlantic Ocean and Gulf of Mexico, there are three seahorse species: the dwarf seahorse Hippocampus zostera, the lined seahorse Hippocampus erectus, and the Brazilian or long-snout seahorse Hippocampus reidi. The dwarf seahorse is one of the smallest seahorse species and grows up to 1 ½” full grown.
Pipefish are very closely related to seahorses, and it is pretty obvious when you look at them because they basically look like stretched out seahorses – or maybe seahorses look like curled up pipefish? What you might not know is that the trumpetfish and cornetfish are also close cousins to seahorses. Seahorses and their cousins all have a long snout that is used to capture prey that is called pivot feeding. Pivot feeding is described by an upward rotation of the head, followed by suction to draw the prey into the snout. They are ambush predators that mainly eat small crustaceans like shrimp, copepods, amphipods, and larval or juvenile fish.
One of the most unique characteristics of seahorses is that the male carries the baby fry through gestation and birth. The male has a brood pouch with an oviduct that the female places the eggs into where they are fertilized. The male will carry the eggs in his pouch while they develop, and after several weeks, the baby seahorses are born alive and ready to fend for themselves. Most female seahorses choose a mate, and stay with that mate for a long time. This is especially apparent when you have seahorses in the aquarium. While I was an intern at Mote Marine Aquarium in Sarasota, Florida, I took care of the seahorse room. Almost every day the mature female seahorse would meet with the male at the bottom of the tank, and they would dance and spin to the top of the aquarium.
Unfortunately, seahorses are under threat especially due to habitat loss all over the world. Seahorses primarily live in seagrass meadows and under mangrove roots, and thousands of acres are being lost every year due to human development, and deforestation on land that causes the soil to wash into the sea and covers seagrass beds. Nutrient enrichment is another problem, when an excess of nitrogen and phosphorus can cause algal blooms that can block the sunlight from reaching the bottom where seagrass grows. They also live on coral reefs that are in steep decline and suffering from increased water temperatures, coral bleaching, and diseases.
Believe it or not, when I was little you could go into almost any souvenir shop in Florida and find huge baskets filled with hundreds of dried seahorses for sale next to sand dollars, sea urchins, and other seashells. Luckily, we do not often see those kind of wasteful souvenirs anymore in the United States. However, there are still huge markets elsewhere in the world for dead and dried seahorses, especially on the black market for illegal wildlife products. Poachers collect seahorses and they are sold in Asia for soups, teas, and traditional Chinese medicines.
I am optimistic because people all over the world are starting to realize that we have to work harder to protect the environment. Hopefully, the tide will turn as we all work together to help protect these animals and environments that are so vital for healthy humans and a healthy world.