Hippocampus ingens

Geographic Range

Giant seahorses are found along the coast of the Eastern Pacific Ocean, from San Diego, California to Peru, including the Cocos, Malpelo, and Galapagos Islands.

• Biogeographic Regions
• nearctic nearctic
  • native native
• neotropical neotropical
  • native native
• oceanic islands oceanic islands
  • native native
• pacific ocean pacific ocean
  • native native

Habitat

Giant seahorses are found over reefs, and in protected bay and subtidal seagrass habitats, from 1-20 m in depth (most commonly from 3-18 m). They are often seen with their tails wrapped around black coral trees, strands of sea grasses and sea whips, and the branches of gorgonian corals, in order to camouflage themselves from predators.

• Habitat Regions
• tropical tropical
• saltwater or marine saltwater or marine

• Aquatic Biomes
• benthic benthic
• reef reef
• coastal coastal

Physical Description

Adult giant seahorses may reach 30 cm in length. Populations display a wide array of body colors, as these animals can change their body color, depending on their environment. Body colors include maroon, yellow, and muddled brownish-green. The darkish body may have small dark and white spots and longitudinal streaks along the length of the body. The neck is curved at a right angle to the rest of the body. Atop the head is a bony structure called a coronet, which has five points, and an elongate snout extends from the front of the face. The backbone structure is unlike that of other vertebrates, with knobby, bony plated rings extending along the tail to the trunk. This makes the tail prehensile and flexible, able to coil around seagrass and other objects. This species displays sexual dimorphism: females typically have a dark patch located ventrally on the anal fin, while males have a slight keel on the chest and a brooding pouch, located under the tail.

• Other Physical Features
• ectothermic ectothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• sexes colored or patterned differently
• sexes shaped differently

Development

Smooth, pear-shaped, yellowish eggs are deposited by a female into a male's breeding pouch, where they are fertilized. The eggs embed in the lining of the brooding pouch and are supplied with oxygen by surrounding capillaries. They develop for 14-15 days, depending on water temperature. After release, typically during full moon high tides, pelagic young are independent. Juveniles are approximately 9 mm in length during the first two months of their lives. As growth proceeds, individuals become mature at approximately 5.4 cm in length.

Reproduction

Although these seahorses are not known to form lifelong pair bonds with mates as some species do, they still exhibit elaborate mating rituals. Males may be aggressive toward each other in competition for females, head butting and tail wrestling each other. Mating pairs will meet and rub their heads together, then intertwine their tails together and around a blade of sea grass or similar structure, performing a mating "dance" by bobbing up and down together. This behavior lasts for three days. Finally, a male will display his empty breeding pouch, which the female will fill with eggs using her ovipositor. After mating and transfer of her eggs to a male, a female typically will not mate again until he has given birth.

• Mating System
• polygynandrous (promiscuous) polygynandrous (promiscuous)

Reproductive activity has been observed in giant seahorses as early as 3 months of age in captivity; at this age, clutch sizes tend to be quite small and males are often unsuccessful at courtship displays. Successful reproductive attempts seem to begin around 6 months of age. Gestation lasts for 14-15 days and brood sizes of up to 2000 have been reported. A particular breeding season has not been identified for these seahorses, though it is thought that they may breed year round. Young are typically released during full moon high tides, providing optimum levels of resources to juveniles.

• Key Reproductive Features
• iteroparous iteroparous
• year-round breeding year-round breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• fertilization fertilization
  • internal internal
• ovoviviparous ovoviviparous

Males retain eggs in their brood pouches until they hatch. After young are released, they are independent and there is no further investment from either parent.

• Parental Investment
• male parental care male parental care
• pre-hatching/birth
  • protecting
    • male

Lifespan/Longevity

The lifespan of giant seahorses varies depending on environmental conditions; the estimated range is 3-5 years.

Behavior

Little is known regarding specific behaviors of this species. In the wild, they are usually observed as solitary creatures, anchored around eelgrass by their prehensile tails. They are nocturnal and non-migratory.

• Key Behaviors
• natatorial natatorial
• nocturnal nocturnal
• motile motile
• sedentary sedentary
• solitary solitary

Home Range

There is no information available to suggest that these animals maintain a particular home range or territory.

Communication and Perception

Specific information regarding the way this species communicates and perceives the environment is scarce. As bony fish, their lateral line system determines pressure and water movements around them. They rely on vision to accurately locate prey when it comes within sight and during courtship, and they possess olfactory nares, which can detect dissolved chemicals. They are also capable of hearing; a clicking sound is produced when mating pairs touch heads as part of courtship behavior.

• Communication Channels
• visual visual
• tactile tactile
• acoustic acoustic

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• vibrations vibrations
• chemical chemical

Food Habits

Diet consists mainly of small crustaceans and zooplankton. Giant seahorses eat brine shrimp ( Artemia sp.) and mysids ( Mysidae sp.), small, shrimp-like crustaceans that are high in protein and lipids. Juveniles may consume phytoplankton. Seahorses lack teeth, instead sucking prey in through their tube-like snouts.

• Primary Diet
• carnivore carnivore
  • eats non-insect arthropods
• planktivore planktivore

• Animal Foods
• aquatic crustaceans
• zooplankton zooplankton

• Plant Foods
• phytoplankton phytoplankton

Predation

However, Giant seahorses have been found in the stomachs of some large fishes. Juveniles face higher risks of predation than adults because of their small size. The camouflage abilities of this species are a great asset in avoiding predation.

• Anti-predator Adaptations
• cryptic cryptic

Ecosystem Roles

Giant seahorses are predators of small crustaceans and zooplankton, while also being a food source to other animals. They may be hosts to parasites or fall victim to bacterial and fungal infections, particularly in captivity.

Economic Importance for Humans: Positive

Giant seahorses are important to the international aquarium trade. They are popular attractions in public aquaria, such as the Birch Aquarium in San Diego, CA and the Aquarium of the Pacific in Long Beach, CA. This species, like all other species of seahorse, is exploited for use in traditional Chinese medicine. These uses have led to population declines and heightened concerns regarding conservation.

• Positive Impacts
• ecotourism ecotourism
• source of medicine or drug source of medicine or drug

Economic Importance for Humans: Negative

There are no known adverse effects of giant seahorses on humans.

Conservation Status

Habitat destruction and overfishing are the biggest threats to the giant seahorse; their populations have declined by 50% from 2007-2012. Each year, it has been reported that thousands of giant seahorses are accidentally caught by shrimp fisheries. While no species of seahorse has been listed as endangered in the U.S. Federal List, the IUCN Red List of Threatened Species cites them as vulnerable. In order to protect these animals, conservation actions have been implemented in some countries. Mexico, for example, has listed giant seahorses as a species subject to special protection, and fishermen are not allowed to intentionally catch these animals. In Panama, the species is listed as protected in a mandate managing coral reefs.

Additional Links

Encyclopedia of Life

Contributors

Bryan Kelley (author), San Diego Mesa College, Sharmaine Mojica (author), San Diego Mesa College, Paul Detwiler (editor), San Diego Mesa College, Jeremy Wright (editor), University of Michigan-Ann Arbor.

References

Beller, P. 2000. " Hippocampus ingens " (On-line). Accessed February 05, 2013 at http://www.oceanoasis.org/fieldguide/hipp-ing.html .

Costeau, J. 1985. The Ocean World . New York: Harry N. Abrams, Inc..

Czembor, C., A. Rojas, A. Acero. 2012. "Hippocampus ingens" (On-line). The IUCN Red List of Threatened Species. Accessed February 19, 2013 at http://www.iucnredlist.org/details/10072/0 .

Dames, N. 2000. "Biogeography of the Pacific Seahorse ( Hippocampus ingens )" (On-line). San Francisco State University. Accessed June 21, 2013 at http://online.sfsu.edu/bholzman/courses/Fall00Projects/seahorse.html .

Foster, S., A. Vincent. 2004. "Life history and ecology of seahorses: Implications for conservation and management" (On-line). Accessed March 14, 2013 at http://www.equilibrioazul.org/documentos/life%20history%20of%20the%20sea%20horse%20management.pdf .

Froese, R., K. Kesner-Reyes. 2012. " Hippocampus ingens (Girard 1858): Pacific Seahorse" (On-line). Fishbase. Accessed June 21, 2013 at http://www.fishbase.org/summary/Hippocampus-ingens.html .

George, T. 2003. Seahorses . Brookfield, Connecticut: The Millbrook Press, Inc..

Gomezjurado, J. 2005. "International Aquarium Forum" (On-line). Syngnathid Husbandry in Public Aquariums. Accessed February 19, 2013 at http://www.intaquaforum.org/hg_FAI_Syngnathid05.pdf .

Koldewey, H. 2005. "Syngnathid Husbandry in Public Aquariums" (On-line). Accessed February 19, 2013 at http://www.intaquaforum.org/hg_FAI_Syngnathid05.pdf#page=72 .

Lourie, S., S. Foster, E. Cooper, A. Vincent. 2004. A Guide to the Identification of Seahorses . Washington, DC: University of British Columbia and World Wildlife Fund.

M. Walker, S. 1999. Sea Horses . A division of Lerner Publishing Group: Carolrhoda Books.

Miller, S. 2002. Seahorses, Pipefishes, and Their Kin . Canada: Scholastic Inc..

Sammon, R. 1995. Secrets of the Coral Reefs: Exploring the Underwater Wonders . Stillwater, MN: Voyageur Press, Inc..

Swartz, S. 2001. Sea Horses and Pipefish . Carlsbad, California: Dominie Press, Inc..

Monterey Bay Aquarium Foundation. 2013. "Pacific Seahorse- On Exhibit: The Secret Lives Of Seahorses" (On-line). Monterey Bay Aquarium. Accessed February 05, 2013 at http://www.montereybayaquarium.org/animals/AnimalDetails.aspx?enc=n3f4wmcSJaPCN6qSlyAupQ== .

2013. "Pacific Seahorses, Hippocampus ingens " (On-line). Accessed February 05, 2013 at http://marinebio.org/species.asp?id=109 .

2013. "Species information: Hippocampus ingens " (On-line). Smithsonian Tropical Research Institute: Shorefishes of the Tropical Eastern Pacific. Accessed June 21, 2013 at http://biogeodb.stri.si.edu/sftep/taxon_option_main.php?lvl=S&id=197 .