Because of their body shape, seahorses are rather inept swimmers and can easily die of exhaustion when caught in storm-roiled seas. They anchor themselves with their prehensile tails to sea grasses and corals, using their elongated snouts to suck in plankton and small crustaceans that drift by.
However, worldwide coastal habitat depletion, pollution, and rampant harvesting, mainly for use in Asian traditional medicine, have made several species vulnerable to extinction. Seahorse (also written sea-horse and seahorse) is the name given to 46 species of small marine fish in the genus Hippocampus.
“Hippocampus” comes from the Ancient Greek hippocampus ( hippocampus), itself from hippos ( hippos) meaning “horse” and Campos ( Campos) meaning “sea monster”. Having a head and neck suggestive of a horse, seahorses also feature segmented bony armor, an upright posture and a curled prehensile tail.
Along with the pipe fishes and sea dragons (Phycodurus and Phyllopteryx) they form the family Syngnathidae. These species form territories; males stay within 1 m 2 (10 sq ft) of habitat, while females range over about one hundred times that.
They are named for their equine appearance, with bent necks and long shouted heads and a distinctive trunk and tail. The armor of bony plates also protects them against predators, and because of this outer skeleton, they no longer have ribs.
The pectoral fins, located on either side of the head behind their eyes, are used for steering. Their prehensile tail is composed of square-like rings that can be unlocked only in the most extreme conditions.
They are adept at camouflage, and can grow and reabsorb spiny appendages depending on their habitat. It also sports a crown-like spine or horn on its head, termed a “coronet”, which is distinct for each species.
The slowest-moving fish in the world is H. zoster (the dwarf seahorse), with a top speed of about 1.5 m (5 ft) per hour. Since they are poor swimmers, they are most likely to be found resting with their prehensile tail wound around a stationary object.
They have long snouts, which they used to suck up food, and their eyes can move independently of each other like those of a chameleon. The best known and best studied fossils are specimens of Hippocampus gutturals (though literature more commonly refers to them under the synonym of H. fabulous), from the Marcia River formation of Bimini Province, Italy, dating back to the Lower Pliocene, about 3 million years ago.
The earliest known seahorse fossils are of two pipefish-like species, H. dramatics and H. Slovenians, from the prolific horizon of Tunic Hills, a middle Miocenelagerstätte in Slovenia dating back about 13 million years. Molecular dating finds that pipe fish and seahorses diverged during the Late Oligocene.
This has led to speculation that seahorses evolved in response to large areas of shallow water, newly created as the result of tectonic events. The shallow water would have allowed the expansion of seagrass habitats that selected for the camouflage offered by the seahorses upright posture.
These tectonic changes occurred in the western Pacific Ocean, pointing to an origin there, with molecular data suggesting two later, separate invasions of the Atlantic Ocean. The male seahorse is equipped with a pouch on the ventral, or front-facing, side of the tail.
When mating, the female seahorse deposits up to 1,500 eggs in the male's pouch. The male carries the eggs for 9 to 45 days until the seahorses emerge fully developed, but very small.
The young are then released into the water, and the male often mates again within hours or days during the breeding season. Scientists believe the courtship behavior synchronizes the animals' movements and reproductive states, so that the male can receive the eggs when the female is ready to deposit them.
During this time, they may change color, swim side by side holding tails or grip the same strand of seagrass with their tails, and wheel around in unison in what is known as a “predawn dance”. They eventually engage in a “true courtship dance” lasting about 8 hours, during which the male pumps water through the egg pouch on his trunk which expands and opens to display its emptiness.
When the female's eggs reach maturity, she and her mate let go of any anchors and drift upward snout-to-snout, out of the seagrass, often spiraling as they rise. The female then swims away until the next morning, and the male returns to sucking up food through his snout.
The female inserts her visitor into the male's brood pouch and deposits dozens to thousands of eggs. As the female releases her eggs, her body slims while his swells.
Both animals then sink back into the sea grass, and she swims away. During this phase the potential mates brighten in color, quiver, and display rapid side-to-side body vibrations.
These displays are performed alternately by both the male and the female seahorse. The following phases, 2 through 4, happen sequentially on the day of copulation.
In phase 3 males will also begin the same pointing behavior in response to the female. Finally, the male and female will repeatedly rise upward together in a water column and end in mid-water copulation, in which the female will transfer her eggs directly into the male's brood pouch.
During this phase the males and females will remain apart during the night, but after dawn they will come together in a side-by-side position, brighten, and engage in courtship behavior for about 2 to 38 minutes. This starts when the male approaches the female, brightens and begins to quiver.
The female will follow the male with her own display, in which she will also brighten and quiver about 5 seconds later. During phase 1 the tails of both seahorses are positioned within 1 cm of each other on the same hold-fast and both of their bodies are angled slightly outward from the point of attachment.
However, the female will shift her tail attachment site, causing the pair to circle their common hold-fast. Phase 2: Pointing and pumping This phase begins with the female beginning her pointing posture, by leaning her body towards the male, who will simultaneously lean away and quiver.
Following phase 2 is a latency period (typically between 30 minutes and four hours), during which the seahorses display no courtship behavior and females are not bright; males will usually display a pumping motion with their body. Each bout of courtship begins with both the male and female anchored to the same plant about 3 cm apart; usually they are facing each other and are still bright from the previous phase.
During the first bout, following the facing behavior, the seahorses will rise upward together anywhere from 2 to 13 cm in a water column. During the final rise the female will insert her visitor and transfer her eggs though an opening into the male's brood pouch.
During fertilization in Hippocampus Cuba the brood pouch was found to be open for only six seconds while egg deposition occurred. This hyper osmotic environment facilitates sperm activation and motility.
The fertilization is therefore regarded as being physiologically ‘external’ within a physically ‘internal’ environment after the closure of the pouch. It is believed that this protected form of fertilization reduces sperm competition among males.
Within the Syngnathidae (pipe fishes and seahorses) protected fertilization has not been documented in the pipe fishes but the lack of any distinct differences in the relation of testes size to body size suggests that pipe fishes may also have evolved mechanisms for more efficient fertilization with reduced sperm competition. Seahorses in Phase 4 of courtship fertilized eggs are then embedded in the pouch wall and become surrounded by a spongy tissue.
The male supplies the eggs with prolactin, the same hormone responsible for milk production in pregnant mammals. Though the egg yolk contributes nourishment to the developing embryo, the male seahorses contribute additional nutrients such as energy-rich lipids and also calcium to allow them to build their skeletal system, by secreting them into the brood pouch that are absorbed by the embryos.
Further they also offer immunological protection, autoregulation, gas exchange and waste transport The eggs then hatch in the pouch, where the salinity of the water is regulated; this prepares the newborns for life in the sea.
Throughout gestation, which in most species requires two to four weeks, his mate visits him daily for “morning greetings”. When the fry are ready to be born, the male expels them with muscular contractions.
He typically gives birth at night and is ready for the next batch of eggs by morning when his mate returns. Like almost all other fish species, seahorses do not nurture their young after birth.
Infants are susceptible to predators or ocean currents which wash them away from feeding grounds or into temperatures too extreme for their delicate bodies. Less than 0.5% of infants survive to adulthood, explaining why litters are so large.
These survival rates are actually fairly high compared to other fish, because of their protected gestation, making the process worth the great cost to the father. This brings into question why the sexual role reversal even takes place.
In an environment where one partner incurs more energy costs than the other, Batsman's principle suggests that the lesser contributor takes the role of the aggressor. Male seahorses are more aggressive and sometimes “fight” for female attention.
According to Amanda Vincent of Project Seahorse, only males tail-wrestle and snap their heads at each other. To estimate the female's direct contribution, researchers chemically analyzed the energy stored in each egg.
By the end of incubation, the male consumed almost 33% more oxygen than before mating. The study concluded that the female's energy expenditure while generating eggs is twice that of males during incubation, confirming the standard hypothesis.
Why the male seahorse (and other members of the Syngnathidae) carries the offspring through gestation is unknown, though some researchers believe it allows for shorter birthing intervals, in turn resulting in more offspring. Given an unlimited number of ready and willing partners, males have the potential to produce 17% more offspring than females in a breeding season.
Also, females have “time-outs” from the reproductive cycle 1.2 times longer than those of males. When the female's eggs are ready, she must lay them in a few hours or eject them into the water column.
Making eggs is a huge cost to her physically, since they amount to about a third of her body weight. To protect against losing a clutch, the female demands a long courtship.
Though seahorses are not known to mate for life, many species form pair bonds that last through at least the breeding season. Some species show a higher level of mate fidelity than others.
However, many species readily switch mates when the opportunity arises. H. Abdominalis and H. crevices have been shown to breed in groups, showing no continuous mate preference.
This hypothesis states, “males remain with a single female because of ecological factors that make male parental care and protection of offspring especially advantageous.” Because the rates of survival for newborn seahorses are so low, incubation is essential. Though not proven, males could have taken on this role because of the lengthy period the females require to produce their eggs.
Seahorses rely on stealth to ambush small prey such as cope pods. Seahorses use their long snouts to eat their food with ease.
However, they are slow to consume their food and have extremely simple digestive systems that lack a stomach, so they must eat constantly to stay alive. Seahorses feed on small crustaceans floating in the water or crawling on the bottom.
With excellent camouflage seahorses ambush prey that floats within striking range, sitting and waiting until an optimal moment. Mys id shrimp and other small crustaceans are favorites, but some seahorses have been observed eating other kinds of invertebrates and even larval fish.
In a study of seahorses, the distinctive head morphology was found to give them a hydrodynamic advantage that creates minimal interference while approaching an evasive prey. After successfully closing in on the prey without alerting it, the seahorse gives an upward thrust and rapidly rotates the head aided by large tendons that store and release elastic energy, to bring its long snout close to the prey.
This step is crucial for prey capture, as oral suction only works at a close range. Seahorses have three distinctive feeding phases: preparatory, expansive, and recovery.
During the recovery phase, the jaws, head, and hold apparatus of the seahorse return to their original positions. The amount of available cover influences the seahorses feeding behavior.
For example, in wild areas with small amounts of vegetation, seahorses will sit and wait, but an environment with extensive vegetation will prompt the seahorse to inspect its environment, feeding while swimming rather than sitting and waiting. Conversely, in an aquarium setting with little vegetation, the seahorse will fully inspect its environment and makes no attempt to sit and wait.
Coral reefs and seagrass beds are deteriorating, reducing viable habitats for seahorses. Additionally, by catch in many areas causes high cumulative effects on seahorses, with an estimated 37 million individuals being removed annually over 21 countries.
They eat frozen MySpace (crustaceans) that are readily available from aquarium stores, and do not experience the stress of moving out of the wild. Although captive-bred seahorses are more expensive, they take no toll on wild populations.
Seahorses should be kept in an aquarium with low flow and placid tank mates. Keepers are generally advised to avoid eels, tangs, trigger fish, squid, octopus, and sea anemones.
Water quality is very important for the survival of seahorses in an aquarium. A water-quality problem will affect fish behavior and can be shown by clamped fins, reduced feeding, erratic swimming, and gasping at the surface.
Therefore, the tanks should ideally be twice as deep as the length of the adult seahorse. Animals sold as freshwater seahorses are usually the closely related pipe fish, of which a few species live in the lower reaches of rivers.
The latter, which is often confused with the former, can be found in estuaries environments, but is not actually a freshwater fish. Seahorse populations are thought to be endangered as a result of overfishing and habitat destruction.
Despite a lack of scientific studies or clinical trials, the consumption of seahorses is widespread in traditional Chinese medicine, primarily in connection with impotence, wheezing, nocturnal enuresis, and pain, as well as labor induction. Preferred species of seahorses include H. Kellogg, H. historic, H. Cuba, H. trimaculatus, and H. moniker.
Seahorses are also consumed by Indonesians, central Filipinos, and many other ethnic groups . However, Indonesia, Japan, Norway, and South Korea have chosen to opt out of the trade rules set by CITES.
The problem may be exacerbated by the growth of pills and capsules as the preferred method of ingesting seahorses. Pills are cheaper and more available than traditional, individually tailored prescriptions of whole seahorses, but the contents are harder to track.
Seahorses once had to be of a certain size and quality before they were accepted by TCM practitioners and consumers. Declining availability of the preferred large, pale, and smooth seahorses has been offset by the shift towards prepackaged preparations, which makes it possible for TCM merchants to sell previously unused, or otherwise undesirable juvenile, spiny, and dark-colored animals.
Today, almost a third of the seahorses sold in China are packaged, adding to the pressure on the species. Dried seahorse retails from US$600 to $3000 per kilogram, with larger, paler, and smoother animals commanding the highest prices.
The species H. Minotaur, H. Denise, H. Coleman, H. pontoon, H. Severn, H. atomize, H. waleananus, and H. Japanize have been described. Other species that are believed to be unclassified have also been reported in books, dive magazines and on the Internet.
They can be distinguished from other species of seahorse by their 12 trunk rings, low number of tail rings (26–29), the location in which young are brooded in the trunk region of males and their tiny size. Character DI Alcuin Nova genera e love specie DI animal e picante Della Sicilian: con varied observation copra i redesign.
^ Hippocampus Romanesque, 1810, Worms ^ Shorter Oxford English Dictionary. Lid dell, Henry George ; Scott, Robert ; A Greek–English Lexicon at the Perseus Project.
^ “Observatory Océanologique de Banyuls SUR MER”. ^ Porter, Michael M; Novitskaya, Ekaterina; Castro-Ceseña, Ana Bertha; Meyers, Marc A; McKittrick, Joanna (2013).
^ Guinness Book of World Records (2009) ^ Laurie, Sara (2016). “Two new species of seahorses (Syngnathidae, Hippocampus) from the Middle Miocene (Dalmatian) Prolific Horizon in Tunic Hills, Slovenia: The oldest fossil record of seahorses “.
“Evolution of seahorses upright posture was linked to Oligocene expansion of seagrass habitats”. ^ These PR; Cherry MI; Matthew CA (2004).
“The evolutionary history of seahorses (Syngnathidae: Hippocampus): molecular data suggest a West Pacific origin and two invasions of the Atlantic Ocean”. ^ Lin, Jiang; Fan, Sheila; Zhang, Yanking; EU, Men; Zhang, Haitian; Yang, Yuan; Lee, Alison P; Weltering, Jews M; Ravi, Vydianathan; Hunter, Helen M; Duo, Wei; GAO, Dexia; LIM, Hi Wei; Qin, Gang; Schneider, Ralf F; Wang, In; XING, Pawn; Li, Gang; Wang, Kai; Min, Jimena; Zhang, Chi; AIU, King; Bad, Die; He, Naming; Ban, Chao; Zhang, Xingu; Shan, Die; EU, Tongue; Sun, King; et al. (14 December 2016).
“Life history and ecology of seahorses : implications for conservation and management”. “Courtship Behavior in the Dwarf Seahorse, Hippocampus zoster “.
^ Look, Katrin J. W. Van; Doubt, Boys; Cliff, Alex; Dewey, Heather J.; Holt, William V. (1 February 2007). “Biomorphic sperm and the unlikely route to fertilization in the yellow seahorse”.
“Testes investment and spawning mode in pipe fishes and seahorses (Syngnathidae)”. ^ Whittington, Camilla M.; Griffith, Oliver W.; QI, Wagon; Thompson, Michael B.; Wilson, Anthony B.
“Seahorse Brood Pouch Transcriptome Reveals Common Genes Associated with Vertebrate Pregnancy”. “Differences in potential reproductive rates of male and female seahorses related to courtship roles”.
^ Lin, Q., Fan, S., Zhang, Y., EU, M., Zhang, H., Yang, Y., Lee, A.P., Weltering, J.M., Ravi, V., Hunter, H.M. and Duo, W. (2016) “The seahorse genome and the evolution of its specialized morphology”. “Monogamous pair bonds and mate switching in the Western Australian seahorse Hippocampus subelongatus “.
“Faithful pair bonds in wild seahorses, Hippocampus white (PDF). “Effect of habitat complexity and predatory style on the capture success of fish feeding on aggregated prey”.
Journal of the Marine Biological Association of the United Kingdom. “Morphology of seahorse head hydro dynamically aids in capture of evasive prey”.
^ Wattenberg, Sam Van; Brother, James A.; Flambeing, Brooke E.; Ferry-Graham, Lara A.; Arts, Peter (6 March 2008). “Extremely fast prey capture in pipe fish is powered by elastic recoil”.
“Morphology and kinematics of prey capture in the syngnathid fishes Hippocampus erects and Syngnathus Florida “. ^ Rosa, Fierce L.; Dias, Thelma L.; Baum, Julia K. (2002).
“Threatened Fishes of the World: Hippocampus radio Ginsburg, 1933 (Syngnathidae)”. Project Seahorse Advancing Marine Conservation, ISBN 0-89164-169-6.
Low by catch rates add up to big numbers for a genus of small fishes American Fisheries Society.10.1080/03632415.2017.1259944 ^ “Seahorse and Pipe fish Foods | Tami Weiss”. “Use of animal products in traditional Chinese medicine: Environmental impact and health hazards”.
^ a b Ben sky, D., Clara, S., Stoner, E. (2004) Chinese Herbal Medicine: Material Media. ^ Laurie, SARA A.; POLL OM, RILEY A.; FOSTER, SARAH J.
Hippocampus Japanize, a new species of pygmy seahorse from Japan, with a redescription of H. pontoon (Teleostean, Syngnathidae)”. ^ a b Zhang, Anthony; Qin, Gang; Wang, In; Lin, Jiang (23 September 2016).
^ a b Short, Graham; Classes, Low; Smith, Richard; DE Brouwer, Marten; Hamilton, Heavy; Stat, Michael; Harass, David (19 May 2021). “ “Three new pygmy seahorse species from Indonesia (Teleostean: Syngnathidae: Hippocampus)” (PDF).
^ These, Peter; Michael Cherry; Conrad Matthew (February 2004). “The evolutionary history of seahorses (Syngnathidae: Hippocampus): molecular data suggest a West Pacific origin and two invasions of the Atlantic Ocean”.