Of the 43 recognized species of seahorses, 12 are on the IUCN Red List of Threatened Species. They inhabit coastal regions all over the world, running the gamut from only .8-inch (2 cm) long (the pygmy seahorse) to 14 inches (35 cm) long (the big-bellied seahorse).
Where to look for seahorses
Seahorses can change color, making them masters of disguise. You can often spot them hiding in seagrass, on staghorn coral, in cracks in walls, or under small overhangs. They even hide on gorgonian coral or among sea urchins or sea feathers. They generally stay in places where there is little to no water movement, as their bodies do not move effortlessly and efficiently through water.
Mating and birth
During their mating ritual, male and female seahorses court by mirroring each other’s movements. Once aligned, the female gives the male the eggs and he either keeps them in his pouch or on a spongy area on his tail. That’s right — the males carry the babies. A female can produce up to 1,500 eggs at once, with smaller species producing more eggs. The young are born live and must immediately fend for themselves. A very small number (about 1 percent) reach maturity and have young of their own. Gestation ranges from two to nine weeks and is often fastest in warm water.
Seahorses have neither teeth nor a digestive system, which means they have to feed frequently. When they eat, swallow their food whole. Typical prey is small guppies, small brine shrimp, crustaceans and plankton.
Common seahorses
Here are the six most common seahorses you might see when diving.
Common seahorse (Hippocampus kuda)
With a head that looks like a horse, a bumpy tummy and a spiral tail, the common seahorse reaches a maximum length of 12 inches (30 cm). Males are larger than females. They come in a variety of colors, but the males are usually a bit grayer with dark spots. The females often have some yellow and dark spots on their bodies. Each common seahorse has a crown on its head, as unique as a human fingerprint. Their bodies are quite smooth compared to other species of seahorses. You’ll find them in on coral reefs in the Indo-Pacific in tropical water between 72 and 77 F (22 to 25 C).
Pygmy seahorse (Hippocampus bargibanti and others)
Pygmy seahorses are about ¾-inch (2 cm) long. They are usually yellow, orange, pink, or gray changing color to blend in with their surroundings. They have a narrower snout than other seahorses and a prehensile tail to hold onto the fan corals they call home. Some live on soft coral or among seagrasses as well. Pygmy seahorses live in larger groups than other seahorse species, gathering in numbers of up to 20 adults. You’ll find pygmies across the Western Pacific from Southern Japan to Northern Australia and out to the Solomon Islands and New Caledonia.
Pygmies are one of the most recently discovered species because they are so small. A scientist from New Caledonia, Georges Bargibant, discovered the species that was subsequently named for him accidentally while examining a gorgonian fan in the lab.
Leafy seadragon (Phycodurus eques)
As their name implies, leafy seadragons (or leafies) look like they have leaves attached to their bodies. Used solely for camouflage, the leafy protrusions help the animals look like bits of floating seaweed. They have both pectoral and dorsal fins and no prehensile tail. They typically grow to between 7.8 and 12 inches (20 and 30 cm) long.
Leafies are endemic to the ocean around Southern Australia, found only from Wilson’s Promontory in Victoria in the east, west to Jurien Bay, 140 miles (220 km) north of Perth in Western Australia. They inhabit temperate waters between 57 to 66 F (14 to 19 C), usually between 13 to 50 feet deep (4 to 15 m). Once you’ve spotted one, don’t worry about losing it — they move only about 1/8 of a mile (200 m) per hour.
Weedy seadragon (Phyllopteryx taeniolatus)
The weedy seadragon is equally as spectacular as its close relative, the leafy seadragon. Measuring between 12 and 15 inches (30 to 38 cm) long, they are camouflaged to blend into their surroundings as well, resembling weeds or seagrass. They are usually green or tan with many ridges and stripes and spots on their bodies. They have no prehensile tail.
You’ll find weedies only along the same southern Australian coastline as leafy seadragons, as well as some areas in Tasmania.
Big-belly seahorse (Hippocampus abdominalis)
The big-belly seahorse, also called the pot-bellied seahorse, averages about 12 inches (30 cm) long, but can grow up to almost 14 inches (35 cm) long. Their snouts tip forward more than other seahorses and they have a coiled, prehensile tail. Their most distinctive feature is the wide, round stomach for which they’re named. The females’ abdomens are smaller with a keel down the middle where the males’ abdomens are larger and smoother. The males also have longer tails and wider snouts than the females.
You’ll find the big-belly seahorse in the coastal areas around New Zealand and Australia. They live in water from 70 to 80 Fahrenheit (21-26 C) or warmer.
Pacific seahorse (Hippocampus ingens)
Pacific seahorses are about 12 inches (30 cm) long, depending on the environment, with the males being slightly larger than the females. Their colors change to blend into their surroundings, ranging from gold to maroon, brown, white or a combination. There is often a dark-colored line down the females’ bodies. During the gestation period the males’ bodies grow much larger than their average size to stay safe from predators.
You’ll find Pacific seahorses in the coastal areas of Colombia, Costa Rica, El Salvador, Mexico, Panama, Peru and the United States. They are the only species of seahorse living in the eastern Pacific Ocean. Pacific seahorses can live in water depths up to 200 feet (61 m). They often float around and blend into areas with brown algae.
Seahorses are fascinating creatures and quite popular among aquarists, which leads to overharvesting from the wild. Their bodies are also commonly dried for use in traditional Chinese medicine, and seahorses also fall prey in vast numbers to shrimp-trawling nets. Unfortunately, these pressures combine to make seahorses endangered in our oceans. Do your part and leave shrimp off your plate and watch seahorses in the wild rather than keeping one in captivity.
