Seahorses are predatory fishes, preying on a variety of small crustaceans, mollusks and various zooplankton. Prey items are captured via a unique suction feeding behavior. Once food is located, a sudden upswing of the head draws it into the mouth, followed by pipette-like suction transport into the buccal cavity (Bergert & Wainwright 1997). The entire prey capture process for each strike is quite rapid, with the total feeding and recovery time lasting less than one second (Bergert & Wainwright 1997). The origin of the clicking sounds produced during the feeding process in seahorses is controversial. Some studies suggest that cavitation occurs during prey capture, producing sound from the collapse of vapor bubbles in the water, which is caused by rapid pressure changes in the buccal cavity (James & Heck 1994). Other experiments support the hypothesis that the sound actually originates from the articulation or contact of two bones in the head, the supraoccipital and the coronet (Colson et al. 1998; Fish et al. 1952; Fish 1953, 1954; Fish & Mowbray 1970).Gut content analysis for individuals in Chesapeake Bay shows a varied diet for H. erectus (Teixeira & Musik 2001). The most common prey items appear to be amphipods, especially Ampithoe longimana, Gammarus mucronatus, Stenothoe minuta and Caprella penantis. Other foods included: copepods; polychaetes; gastropods; and grass shrimp in the family Palaemonidae. In captivity, juveniles and adults have been reared on a variety of foods, including: live and frozen nauplius and adult stages of the brine shrimp, Artemia spp.; live and frozen Mysis shrimp; grass shrimp; copepods; gammarid and caprellid amphipods; fry of the killifish, Poecilia sp.; and frozen krill, Euphausia pacifica (Lin et al. 2008, Martinez et al. 2005). Predators: Information on specific predators of the lined seahorse is scarce, but the camouflage behavior of this species among seagrass blades, algae and mangrove roots reduces predation risk. However, mobility in H. erectus is limited and larger fishes likely prey on adults and juveniles. In addition, captive parental males have been documented to cannibalize small numbers of their own fry following release into the water column (Lin et al. 2008). Parasites: The lined seahorse is vulnerable to several parasitic infections, especially in captive adults and aquacultured juveniles. Documented parasites include: microsporidians, including Glugea heraldi (Blasiola 1979, Vincent & Clifton-Hadley 1989); a myxosporidian of the genus Sphaeromyxa (Vincent & Clifton-Hadley 1989); fungi (Blazer & Wolke 1979); ciliates, including Uronema marinum (Cheung et al. 1980); and nematodes (Vincent & Clifton-Hadley 1989). Activity Time: Like most other syngnathids, H. erectus is diurnal, actively feeding and engaging in other behaviors during the day.
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