As divers, we are often looking for large species, like sharks, manta rays, and ancient sea turtles. Still, many smaller creatures add their own special touch of magic to a dive; one favorite is the seahorse. Found in a variety of places all over the world, these intriguing little creatures are a favorite subject for photographers; and as marine life goes, they are simply fascinating. Let’s take a look.
Seahorses: Basic Information
Part of the Syngnathidae family, which includes pipefish, the nearly fifty seahorse species compose the genus Hippocampus, which originates from the Greek Hippos and Kampos, meaning “horse” and “sea monster”, respectively. Mostly found in shallow tropical and temperate waters throughout the world, they require sheltered habitats, such as coral reefs, mangroves, and beds of seagrass.
Named for their head shape, which is much like that of a horse, sea horses are scaleless fish with thin skin stretched across bony plates that are arranged in a circular pattern around their bodies. Every seahorse has a coronet on its head, which is distinct only to it, allowing for easy identification.
Seahorses eat small brine shrimp and other crustaceans, tiny fish, and lots of plankton. In all, they suck up about 3,000 little organisms each day with their long, curious snouts.
Diving With Seahorses
These territorial fish occupy relatively small areas, with the females sticking to about a 100 square meter area and the males remaining within a tiny area of about a meter square.
There are three species of seahorses living in the Mediterranean Sea, and from North America to South America, there are four very common species, ranging from Dwarf seahorses less than an inch long, to Lined Seahorses, which are much larger with the largest recorded specimen having been 8 inches in length. Seahorses have also been found in European waters, including the Thames Estuary. Some additional places which are renowned for their seahorse populations are the Galapagos Islands, Australia’s Osprey and Ribbon Reefs, and a variety of Indo-Pacific locations like Thailand, Indonesia, and Malaysia.
Most sea horses camouflage themselves by taking on a murky grey or brown pattern to blend in with their surroundings, although they do turn bright colors like red or yellow during social interactions and when placed in unusual surroundings. Unlike most fish, they swim with an upright profile, bobbing as they go. They have no caudal fins, and to propel themselves throughout the water, they flutter their dorsal fins rapidly. They use their pectoral fins, which are located behind their eyes, to steer with.
As swimming takes quite a bit of energy, seahorses are usually found resting, with their tails anchoring them to stationary objects. Like chameleons, they have eyes that can move independently of one another, and their tails are prehensile.
If you are lucky, you may get to witness seahorse courting or egg rearing behavior. Unlike most other species, sea horses have a tendency to be monogamous. They choose a mate for life, rearing one clutch of eggs after another. In another odd twist of events, it is the male seahorse which carries the developing seahorses inside his body.
Before breeding, seahorses court for several days, often swimming side by side with their tails held together. Sometimes they change colors as they move. Often, they will grasp the same piece of sea grass, spinning around it in a display of affection known as the predawn dance. During the last 8 or so hours of courtship, the male seahorse pumps water through his brood pouch, which is located on his front side. Once it is open, and the female is ready to deposit as many as 1,500 eggs in to the pouch, they drift upward, face to face, usually spiraling as they go. As the female releases her eggs, she becomes slimmer, while the male’s body swells. When finished, the female swims away while the male returns to his nest.
Amazingly, male seahorses produce prolactin, which is the same hormone mammals use for milk production, to nourish the eggs as they are developing inside his body. The eggs then hatch inside the pouch, and after a period of 9 to 45 days, fully formed miniature seahorses are released into the water, usually at night. They are capable of functioning on their own, and do not require further care from either the male or female. Less than half of one percent of the offspring survive into adulthood; still, this is a higher percentage than that of most other fish.
The female does not leave her mate alone during his pregnancy; instead, she returns each morning for a courtship-like interaction that lasts just over five minutes per day in most cases. After visiting, she departs until the following day. Once the baby seahorses have been released, the process of courting normally resumes again right away – a male seahorse is thought to be pregnant approximately 70 percent of his life.
Sea horses are sensitive creatures; they tend to dislike bright lights. If you place a red filter or a red plastic bag secured in place with a rubber band over your dive light, you can usually get good photos; they will normally turn their heads away in cases where they are feeling stressed about bright lights.
Unfortunately, sea horses are becoming more vulnerable to human threats all the time. In China, there is a demand for dried seahorse for applications in traditional Chinese medicine, and all told, Asian nations consume approximately 45 tones, or 16 million sea horses annually. In most other places, they are at risk of being collected for the aquarium trade. While not yet considered an endangered species, they are red-flagged on conservation lists, and many nations have taken up measures to protect them from further predation. Besides the direct threats from human consumers, seahorses are vulnerable due to quickly declining habitat. Coral reefs, mangroves, and sea grass beds are all threatened in various places throughout the world; particularly in developing nations. By practicing good conservation methods and helping to educate others, we can help save sea horses and many other sea creatures from facing further decline.