Seahorse

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This article is about the animal. For other uses, see Seahorse (disambiguation).

Hippocampus

Seahorse, Hippocampus sp.

Scientific classification

Kingdom:	Animalia
Phylum:	Chordata
Class:	Actinopterygii
Order:	Syngnathiformes
Family:	Syngnathidae
Genus:	Hippocampus Cuvier (1816)^[1]

Species

See text for species.

Seahorses are marine fish belonging to the genus Hippocampus and of the family Syngnathidae, which also includes pipefish. They are found in temperate and tropical waters all over the world.

Seahorses range in size from 16 mm (the recently discovered Hippocampus denise^[2]) to 35 cm. Seahorses and pipefishes are notable for being the only species in which males become "pregnant".^[3]

It has a dorsal fin located on the lower body and pectoral fins located on the head near their gills. Some species of seahorse are partly transparent and are rarely seen in pictures.

Seahorse populations have been endangered in recent years by overfishing. The seahorse is used in traditional Chinese herbology, and as many as 20 million seahorses may be caught each year and sold for this purpose.^[4]

Import and export of seahorses has been controlled under CITES since May 15, 2004.

Sea dragons are close relatives of seahorses but have bigger bodies and leaf-like appendages which enable them to hide among floating seaweed or kelp beds. Seahorses and sea dragons feed on larval fishes and amphipods, such as small shrimp-like crustaceans called mysids ("sea lice"), sucking up their prey with their small mouths. Many of these amphipods feed on red algae that thrives in the shade of the kelp forests where the sea dragons live.

Seahorses reproduce in an unusual way: the male becomes pregnant. As stated on The Seahorse Project, "The female inserts her ovipositor into the male’s brood pouch, where she deposits her eggs, which the male fertilizes. The fertilized eggs then embed in the pouch wall and become enveloped with tissues." New research indicates the male releases sperm into the surrounding sea water during fertilization, and not directly into the pouch as was previously thought.^[5] Most seahorse species' pregnancies lasts approximately two to three weeks.

Hatched offspring are independent of their parents. Some spend time developing among the ocean plankton. At times, the male seahorse may try to consume some of the previously released offspring. Other species (H. zosterae) immediately begin life as sea-floor inhabitants (benthos).

Seahorses are generally monogamous, though several species (H. abdominalis among them) are highly gregarious. In monogamous pairs, the male and female will greet one another with courtship displays in the morning and sometimes in the evening to reinforce their pair bond. They spend the rest of the day separate from each other hunting for food.

1 As pets
2 Other adaptations
3 Species
4 See also
5 Notes
6 Gallery
7 Books
8 Seahorses in popular culture
9 Articles
10 External links
11 References

[edit] As pets

Seahorses (Hippocampus erectus) at the New England Aquarium.

While many aquarium hobbyists keep seahorses as pets, seahorses collected from the wild tend to fare poorly in a home aquarium. They will eat only live foods such as brine shrimp and are prone to stress in an aquarium, which lowers the efficiency of their immune systems and makes them susceptible to disease.

In recent years, however, captive breeding of seahorses has become increasingly widespread. These seahorses survive better in captivity, and they are less likely to carry diseases. These seahorses will eat mysid shrimp, and they do not experience the shock and stress of being taken out of the wild and placed in a small aquarium. Although captive-bred seahorses are more expensive, they survive better than wild seahorses, and take no toll on wild populations.

Seahorses should be kept in an aquarium to themselves, or with compatible tank-mates. Seahorses are slow feeders, and in an aquarium with fast, aggressive feeders, the seahorses will be edged out in the competition for food. Special care should be given to ensure that all individuals obtain enough food at feeding times.

Seahorses can co-exist with many species of shrimp and other bottom-feeding creatures. Fish from the goby family also make good tank-mates. Some species are especially dangerous to the slow-moving seahorses and should be avoided completely: eels, tangs, triggerfish, squid, octopus, and sea anemones.

Animals sold as "freshwater seahorses" are usually the closely related pipefish, of which a few species live in the lower reaches of rivers. The supposed true "freshwater seahorse" called Hippocampus aimei was not a real species, but a name sometimes used for individuals of Barbour's seahorse and Hedgehog seahorse. The latter is a species commonly found in brackish waters, but not actually a freshwater fish.

[edit] Other adaptations

A seahorse has highly mobile eyes to watch for predators and prey without moving its body. Like the leafy sea dragon, it also has a long snout with which it sucks up its prey. Its fins are small because it must move through thick water vegetation. The seahorse has a long, prehensile tail which it will curl around any support such as seaweed to prevent being swept away by currents.

[edit] Species

Genus Hippocampus
- Big-belly seahorse, Hippocampus abdominalis Lesson, 1827 (New Zealand and south and east Australia)
- Winged seahorse, Hippocampus alatus Kuiter, 2001
- West African seahorse, Hippocampus algiricus Kaup, 1856
- Narrow-bellied seahorse, Hippocampus angustus Günther, 1870
- Barbour's seahorse, Hippocampus barbouri Jordan & Richardson, 1908
- Pygmy seahorse, Hippocampus bargibanti Whitley, 1970 (West Pacific area (Indonesia, Philippines, Papua New Guinea, Solomon Islands, etc)
- False-eyed seahorse, Hippocampus biocellatus Kuiter, 2001
- Réunion seahorse, Hippocampus borboniensis Duméril, 1870
- Short-head seahorse, Hippocampus breviceps Peters, 1869 (south and east Australia)
- Giraffe seahorse, Hippocampus camelopardalis Bianconi, 1854
- Knysna seahorse, Hippocampus capensis Boulenger, 1900
- Hippocampus colemani Kuiter, 2003
- Tiger tail seahorse, Hippocampus comes Cantor, 1850
- Hippocampus coronatus Temminck & Schlegel, 1850
- Denise's pygmy seahorse, Hippocampus denise Lourie & Randall, 2003
- Lined seahorse, Hippocampus erectus Perry, 1810 (east coast of the Americas, between Nova Scotia and Uruguay)
- Fisher's seahorse, Hippocampus fisheri Jordan & Evermann, 1903
- Sea pony, Hippocampus fuscus Rüppell, 1838 (Indian Ocean)
- Big-head seahorse, Hippocampus grandiceps Kuiter, 2001
- Long-snouted seahorse, Hippocampus guttulatus Cuvier, 1829
- Eastern spiny seahorse, Hippocampus hendriki Kuiter, 2001
- Short-snouted seahorse, Hippocampus hippocampus (Linnaeus, 1758) ( Mediterranean Sea and Atlantic Ocean)
- Thorny seahorse, Hippocampus histrix Kaup, 1856 (Indian Ocean, Persian Gulf, Red Sea, and the Far East)
- Pacific seahorse, Hippocampus ingens Girard, 1858 (Pacific coast of North, Central and South America
- Jayakar's seahorse, Hippocampus jayakari Boulenger, 1900
- Collared seahorse, Hippocampus jugumus Kuiter, 2001
- Great seahorse, Hippocampus kelloggi Jordan & Snyder, 1901
- Spotted seahorse, Hippocampus kuda Bleeker, 1852
- Lichtenstein's Seahorse, Hippocampus lichtensteinii Kaup, 1856
- Bullneck seahorse, Hippocampus minotaur Gomon, 1997
- Japanese seahorse, Hippocampus mohnikei Bleeker, 1854
- Monte Bello seahorse, Hippocampus montebelloensis Kuiter, 2001
- Northern spiny seahorse, Hippocampus multispinus Kuiter, 2001
- High-crown seahorse, Hippocampus procerus Kuiter, 2001
- Queensland seahorse, Hippocampus queenslandicus Horne, 2001
- Longsnout seahorse, Hippocampus reidi Ginsburg, 1933 (Caribbean coral reefs)
- Half-spined seahorse, Hippocampus semispinosus Kuiter, 2001
- Dhiho's seahorse, Hippocampus sindonis Jordan & Snyder, 1901
- Hedgehog seahorse, Hippocampus spinosissimus Weber, 1913
- West Australian seahorse, Hippocampus subelongatus Castelnau, 1873
- Longnose seahorse, Hippocampus trimaculatus Leach, 1814
- White's seahorse, Hippocampus whitei Bleeker, 1855 (east Australia)
- Zebra seahorse, Hippocampus zebra Whitley, 1964
- Dwarf seahorse, Hippocampus zosterae Jordan & Gilbert, 1882 (Gulf of Mexico and the Caribbean)

[edit] See also

A sculpture of a heraldic seahorse that adorned an 18th or 19th century French naval vessel

In heraldry, a seahorse is depicted as a creature with the foreparts of a horse and the hindparts of a fish. See, for example, the right supporter of the Isle of Wight Arms, the supporters on either side of the crest of the city of Newcastle upon Tyne, or the coincidental arms of the University of Newcastle, Australia.

The seahorse is prominent in the logo of Waterford Crystal and the logotype of illustrator W. W. Denslow.

In China, seahorses were once thought to be baby dragons.

In the Seri culture of northwestern Mexico, the legend is that the seahorse is a person who, to escape his pursuers, fled into the sea, placing his sandals in his waistbelt at his back.^[6]

[edit] Notes

^ "Hippocampus". FishBase. Ed. Ranier Froese and Daniel Pauly. May 2006 version. N.p.: FishBase, 2006.
^ Pictures of smallest seahorse Hippocampus denise on Project Seahorse web site
^ Jones, Adam G.; Avise, John C. (2003-10-14). "Male Pregnancy" (HTML). Current Biology 13 (20): R791.
^ "Seahorse Crusader Amanda Vincent" on Nova television show
^ http://news.independent.co.uk/world/science_technology/article2165477.ece
^ http://lengamer.org/admin/language_folders/seri/user_uploaded_files/links/File/Textos/Hipocampo/Hipocampo_Metadata.htm

[edit] Gallery

Seahorse, Turneffe Island, Belize

Seahorse, St. Croix, Virgin Islands

Potbelly seahorse pair link tails at the Tennessee Aquarium.

[edit] Books

Sara A. Lourie, Amanda C.J. Vincent and Heather J. Hall: Seahorses: An Identification Guide to the World's Species and their Conversation. London: Project Seahorse, 1999

John Sparks: Battle of the Sexes: The Natural History of Sex. London: BBC Books, 1999

[edit] Seahorses in popular culture

In SpongeBob SquarePants, seahorses (and also "sea ponies") are a common sight. However, their name is taken literally as they have horse-like heads and behave like horses, yet in the movie, they resemble real seahorses.

The National Society for Epilepsy chose a seahorse for its mascot named Cesar (after the Roman emperor, Julius Caesar, who was believed to have had epilepsy). The seahorse mascot was chosen because the hippocampus, a part of the brain that is resistant to damage from epileptic seizures, resembles a seahorse in shape.

The Pokémon Horsea and its evolved forms, Seadra and Kingdra, are loosely based on the seahorse, despite being classed as "dragon" Pokémon.

[edit] Articles

Amanda C.J. Vincent and Laila M. Sadler. "Faithful pair bonds in wild seahorse, Hippocampus whitei." Animal Behaviour 50(1995): 1557-1569.

Amanda C.J. Vincent. "A role for daily greetings in maintaining seahorse pair bonds." Animal Behaviour 49 (1995): 258-260.

Amanda C.J. Vincent. "A seahorse father makes a good mother." Natural History, 12 (1990): 34-43.

Ananda C.J. Vincent and Rosie Woodroffe. "Mothers little helpers: patterns of male care in mammals." Trends in Ecology and Evolution, 9 (1994): 294-297.