What is a pygmy seahorse? Pygmy seahorses are part of the genus Hippocampus which all seahorses belong. They are minute seahorse species found through the world, most less than one inch in size. While they have been known about to science since the discovery of H. bargibanti in 1969, most species have been discovered within the past 10 years. Since then, they have become one of the most popular creatures for recreational divers to seek out.
Pygmy seahorses make up an informal group of nine species, which are:
- Hippocampus bargibanti
- Hippocampus colemani
- Hippocampus debelius
- Hippocampus denise
- Hippocampus minotaur
- Hippocampus pontohi
- Hippocampus satomiae
- Hippocampus severnsi
- Hippocampus waleananus
Pygmy seahorses are unique from other seahorse species in that they are much smaller, less than an inch tall. In fact, they are the smallest seahorses in the world, and the record holder H. satomiae is only 13mm tall when fully grown. That’s just barely over a half an inch! They are also closely associated with their host as they possess the amazing ability to mimic it which protects them from predators. Because of this, new species of pygmy seahorses are still being discovered! Unlike many other seahorses, the pygmy seahorse does not have recognizable body rings. Other things that make them different from other species of seahorse not having a fully formed pouch and some types having a single gill slit such as H. colemani, H. pontohi, and H. severnsi.
To complicate matters, there is great variation with in the appearance of a single species. So far, two color types of H. bargibanti have been identified. They can be grey or purple with pink or red tubercles (small wart-like or angular swellings), or yellow with orange tubercles. These color morphs are essential to match their environment. It is unknown if they can change colors according to different backgrounds. They live in gorgonian corals that highly resemble them. H. denise only grow up to 1.5cm and is usually yellowish brown but can be found in other colors to match its host gorgonian. H. satomiae is the smallest at only 13 millimeters, the fry are black, but they change to match their host corals as adults.
All Pygmy seahorses are distinguished as having a plump head and body, a short truncated snout, and a long tail capable of clinging to coral. Species can be differentiated by colors, size, and other characteristic appearances. H. severnsi, for example, lacks tubercles on its head. All seahorses swim upright with their head up and tail down, and are propelled forward with their dorsal fin. These seahorses normally stay still and will let go of its host to relocate a few centimeters at a time when disturbed. They can swim for about a minute and can also float. Different species of pygmy seahorses vary in color and distinctness of tubercles.
Why are they only being discovered now? Since no one knew they existed, they were not being looked for. Because of their astonishing camouflage, they were easily overlooked until 1969 in New Indonesia when H. bargibanti was discovered. It was found on accident when a biologist was observing Muricella sp. gorgonians which were retrieved by divers. The biologist found the tiny seahorse was using the gorgonian as its host. This species was so well hidden that they were not even noticed until the coral was examined in a lab! Many species of pygmy seahorses were discovered just recently, including Hippocampus debelius, or the soft-coral seahorse, which was revealed in 1993 by an underwater photographer. Severn’s pygmy seahorse, Pontoh’s pygmy seahorse, and Satomi’s pygmy seahorse were just named at the end of 2008! The majority of pygmy seahorses have been found by divers instead of scientists. Scientists then later verified the divers findings.
All seahorses are carnivores. Pygmy seahorses feed on zooplankton, primarily copepods. H. bargibanti has been observed eating zooplankton captured in the polyps of its host coral. They do not have tongues or teeth. Prey is sucked into the seahorse’s mouth once it is within range. They have very small mouths so they require areas that flourish with its natural food. This species also does not have a stomach for digestion, making their digestive systems inefficient. Therefore, food must constantly be ingested to survive since they do not have a place to store its food.
Much of their life cycle is a mystery, but we know a little about the longest discovered species, H. bargibanti, from observations in the wild. Males begin courting by approaching females while changing into a lighter color. The male shakes its head energetically until the female’s attention is gained and she consents to mate. Males would cling to a hitching post near the female and flap its dorsal fin rapidly to gain her attention. In this case the female would accept by grabbing onto his tail and delivering her eggs into his pouch while spinning towards the water surface. The time in mating ranges from a few hours to several days. A female prepares the eggs and deposits them into the pouch of the male. Unlike larger species, pygmy seahorses do not have a brood pouch at the based of the tail. Eggs are includes within the trunk region.
They carry about 10-20 eggs per breeding. The eggs are fertilized and incubated until hatching time. Offspring are born live about two weeks later and are then independent from parents. Fry, or baby seahorses, usually cling to coral reefs and feed immediately after birth. They look just like miniature versions of the parents. Little is known about the pygmy seahorse’s life cycle, although other small seahorses species are known to live for around a year.
Pygmy seahorses are found in the costal regions of the Indo-Pacific Ocean, including Indonesia, New Guinea, Great Barrier Reef, New Caledonia, Japan, and the Philippines. They range from 3 °N – 23 °S and do not migrate. The water depth of the H. bargibanti coral reef habitat ranges from 10m to 40m. H. colemani resides in depths of 5m while H. minotaur prefers depths of 64-110m. The majority tends to prefer shallow waters. They live within a temperature range of 72 – 82 °F (22 – 28 °C).
Pygmy seahorses are marine fish and live in coastal reefs on gorgonians. Different species live on different kinds of gorgonian corals ranging from Anella to Muricella. H. colemani is found among Zostera and Halophila plants. The coral provides a safe hiding place for them. They blend in perfectly with their colors matching that of the coral as well as similar texture, since they have tubercles that go with the polyps of coral. H. waleananus are often found on soft corals and have exceptionally long tails. Up to 28 pairs of adult pygmy seahorses can be found on a single gorgonian, as adults are usually paired together and are often monogamous. They are mostly found in tropical waters.
Threats and Conservation
Since pygmy seahorses are camouflaged so well, specific information of the population trends, distribution, and amount of pygmy seahorses is unknown. Because little is known, they are classified as “Data Deficient.” It is probable that they will be collected for trade for their remarkable beauty. Research must be administered to this species in order to find out its status so that policies can be implemented to keep them safe and protected. However, this will prove to be challenging because of its ability to hide so well. It is important that they are secure from exploitation of their stunning appearance. There are already projects and teams committed to conserving seahorses and their habitats.
Pygmy seahorses are only found living in coral reefs, sea grass beds, and algae, which makes them vulnerable to habitat destruction of that species of coral is destroyed. Most of the host corals have been found to be nearly impossible to maintain in captivity. Because these corals can only thrive in the wild, it is possible that divers may disrupt the environment of the pygmy seahorses. Gorgonian corals are susceptible to destruction by divers and that is not good for the pygmy seahorses, since their survival largely depends on the corals. It is important that divers follow recommended guidelines to viewing these animals.
Diving with Pygmy Seahorses
Pygmy seahorses can be found coastal areas ranging from southern Japan and Indonesia to northern Australia and New Caledonia. They normally reside in depths of 10-40m on reefs. These distinctive pygmy seahorse species have attracted the attention of divers worldwide, making it extremely valuable to the diving industry. In Sabah, a colony of pygmy seahorses is visited by about 100 divers per day. Unfortunately, these visits can be dangerous to the seahorses. With photographers constantly taking pictures, the flashes from cameras could possibly influence them in negative ways. At this time, there are no policies to protect them from harm.
If you happen to come across a pygmy seahorse, please remember to follow these tips. You may look at them but always be careful around pygmy seahorses. Do not touch or attempt to move them. Obviously, do not try to collect them for pet-owning or trade purposes. Keep flashlights and flash photography away from them. Avoid touching or destroying the seafan and take note of the coral around you. They are sensitive to stress and dislike flashes and harassment from divers. Pygmy seahorses are safe as long as they are not disturbed in any way. We want these beautiful and colorful creatures to stay.
Pygmy seahorses are not suitable for home aquariums because their survival likely depends on host corals. Waikiki Aquarium has attempted to keep the host gorgonian for H. bargibanti, and was unable to keep it alive more than a few months. These species of seahorses have very small mouths, making them difficult to feed in a closed system. Not only is the environment for pygmy seahorses hard to maintain, it is probably impossible to obtain the seahorses themselves anyway since they are so rare. They are extremely delicate and are better off living in the wild.
If one wants to keep a miniature species of seahorse in an aquarium, consider looking into the Hippocampus zosterae, also known as the dwarf seahorse, instead. Dwarf seahorses are much less sensitive to captive conditions and are easier to take care of. Pygmy seahorses are often confused with dwarf seahorses in literature. Although both are similarly tiny, they are not the same. Dwarf Seahorses do have the similar appeal of being tiny but make better pets.