Seahorses

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Many people are surprised and excited to find that the northern lined seahorse, Hippocampus erectus, is native to the waters of Long Island. Though dubbed by the Greek as “horse” (hippo) and “sea monster” (campus), the seahorse is a docile, slow-moving, non-aggressive and genuinely unique creature. It is unfortunate that because of these traits the seahorse is more susceptible to changes (human made or natural) in their environment. It is because of their sedimentary “home-body” and monogamous lifestyle, a structured habitat suites the seahorse best. Past research has deemed the complex habitat structure of seagrass to be the favorite home to the seahorse and serves their complex feeding and social structure well (James and Heck 1994). The depletion of eelgrass, Zostera marina, has not helped the seahorse plight. In fact, the species is listed as “vulnerable” on the World Conservation Union’s red list of endangered species. Our hope is that with the restoration of eelgrass, seahorses will once again populate the Peconic Estuary.

This spring, with the help of expert Todd Gardner from Riverhead’s Atlantis Marine World Aquarium we will be releasing the Hippocampus erectus species into one of our restored eelgrass sites. We hope to find that H. erectus will adapt to its old home in Peconic estuary. We’ll keep you updated on their success.    

Seahorses are actually true fish, though they have characteristics that make them different than most fish. Hippocampus species have a horse-like curved down head, skin (no scales), a snout that sucks in food, and eyes that can move independent of each other (Foster and Vincent 2004). Hippocampus erectus, in particular, can be identified by white lines down the neck and white dots on the tail. They show considerable site fidelity in that they do not travel far off their home range of approximately 1-2 m².

By far, one of the most interesting facts about the seahorse is that male seahorses become pregnant! In Hippocampus species, the male becomes impregnated by the female (he carries the fertilized eggs), goes into labor and expels live baby seahorses (Lourie and Foster 2004). Once a male finds a female to breed with, both the male and his female mate stay faithful to each other during breeding season and, in many instances, throughout their life. The male and the female do a “dance” once a day. The monogamous seahorse pair meets up, exchange colors and “promenade” and/or interlock their tails and “dance” together for a few minutes before going their separate ways; the next day they will repeat this ritual. Once the pair mate, they will continue to mate together for the season and, in many cases, for years to come. If a mate finds itself to be widowed, only then will he/she search for a new mate in the following season. While mating, the male receives the female’s eggs and caries them until birth. Gestation lasts approximately 21 days (Foster andVincent 2004). At this point the male goes into “labor”. The male pushes and thrusts for a couple of hours and expels developed juvenile seahorses.

Another intriguing fact about the seahorse is its ability to camouflage. They are capable of changing colors ranging from ash grey, orange, brown, yellow, red, and black to blend into their environment (Lourie & Foster, 2004). It is an important adaptation because it allows seahorses to hide easily from predators as well as aids in predation success on prey organisms like amphipods, copepods, and other small crustaceans. Complex habitat structures, like eelgrass beds, are advantageous to a predator like H. erectus, permitting it to hone in on its natural ability of careful movement and visual orientation.

Seagrasses, though not essential, are important to seahorses. A seahorse will use a blade of seagrass as a “holdfast”. The seahorse will wrap its tail around the blade to stay in place without expending much energy when rough waters might otherwise whisk the seahorse away.  It is also interesting to note that density and height of seagrasses is not important (James & Heck, 1994). What is important, however, is the presence of seagrass.  

Our interest in the seahorse lies in its relationship with eelgrass. One of the many goals of eelgrass restoration efforts is reflected in the theory that once restored, eelgrass- a keystone species and habitat engineer- will support other species of both monetary and ecological importance.

Links:

Atlantis Marine World: 431East Main Street, Riverhead, NY 11901

http://www.projectseahorse.org

http://www.seahorse.com/

References:

Foster, S.J. and A.C.J. Vincent, 2004. Life history and ecology of seahorses: implications for conservation and management. Journal of Fish Biology. 65: 1-61.

James, P.L. and K.L. Heck, Jr., 1994. The effects of habitat complexity and light intensity on ambush predation within a simulated seagrass habitat. Journal of Experimental Marine Biology And Ecology. 176: 187-200.

Lourie, S. A., Sarah J. Foster, Ernest W. T. Cooper, and Amanda C. J. Vincent, 2004. A Guide to the Identification of Seahorses. Project Seahorse and TRAFFIC North America. Washington D.C.: University of British Columbia and World Wildlife Fund. 1-120.