The Lined seahorse typically reaches a length of five to seven inches, although they have been reported to reach a length of eight inches. In almost all cases, the males outgrow the females. In the wild, the Lined seahorse typically has a lifespan of approximately one to four years; however, in captivity their lifespan usually is four years.  They have a broad color spectrum, ranging from black, grey, brown, and green, to orange, red, and yellow. However, their colors may change due to an altercation in their environment, diet, anxiety or stress level, and/or mood.  The Lined seahorse is brawny and upright in appearance, and their armor-like body is followed by a prehensile tail. The Lined seahorse uses its infamous tail to grasp onto its environment composed of seaweed and coral. When a Lined seahorse is very young (two weeks to four weeks), the tail is extremely limber. Typically, the tail is curled forward; the tail is seldom found aligned. The seahorse's body is enclosed into a skeleton-like outer layer that is composed of approximately fifty bony plates that are rectangular in shape. The eyes of the Lined seahorse can concentrate together, or they can operate independently of one another. Unlike the female Lined seahorses, the males have a pouch on their abdominal side that is utilized in reproduction.  The Lined seahorse may be considered sexually mature as early as four months; however, it is typically about eight months. 
Habitat and Distribution
Hippocampus erectus is found in the Atlantic Ocean, spotted as far north as Nova Scotia, Canada, and as far south as Venezuela in South America. They can be found on the east coast of America in Connecticut, Delaware, Florida, Georgia, Lousiana, Maryland, New Jersey, New York, and North Carolina, as well as in the waters surrounding Mexico and the Caribbean. Species found in Brazil seem to be of a different species, however, more research is needed to determine. The Lined seahorse is native to the following locations (alphabetical order): "Belize; Bermuda; Canada (Nova Scotia); Costa Rica; Cuba; Guatemala; Haiti; Honduras; Mexico (Veracruz, Yucatán); Nicaragua; Panama; Saint Kitts and Nevis; the United States; and Venezuela." The species is common in depths of water up to seventy-three meters. The habitat of the Lined seahorse consists of marine vegetation, such as "mangroves, seagrass, sponges, and floating Sargassum." Depending on the season, the species can be found in shallow waters or deep waters in "channels of bays, along beaches, or in or near salt marshes, and over oyster beds and weed-covered banks." In the winter, the seahorses are more prominent in deeper waters, versus warmer months, where they can be found in shallow waters in the various types of aquatic vegetation mentioned above. 
The Lined seahorse utilize their elongated snouts in order to consume their prey, consisting primarily of minute crustaceans. The seahorse sucks its prey through their tubular snouts, with great accuracy if its prey is within one inch from their snout. A growing hippocampus erectus may feed continuously for up to ten hours a day, engulfing approximately 3,600 baby shrimp high in salt content. In order to capture their prey, the seahorse employs color changes to camouflage oneself with his/her surrounding environment.  
Like all species of seahorses, the Lined seahorse reproduces sexually, laying eggs every season. In addition, as with all other seahorses, the male is the parent that looks after the newborn seahorses. The male seahorses have a pouch (called a brood pouch ) used for incubation of the 250 to 650 eggs the female "sprays" into the male's "pocket." The number of eggs the female produces varies, depending on the size of the seahorse. The eggs laid by the female are incubated in the male's marsupial-like pouch for approximately 20 to 21 days until hatching; once hatched, the seahorses are considered embryos until they are capable of swimming on their own. When this time finally approaches, the male latches his prehensile tail onto a supportive object while he braces back and forth, until the developed seahorses escape from the pouch. The bracing continues until all seahorses have successfully escaped the pouch. H. erectus newborns are approximately 5/8 of an inch and do not reach maximum size until they are 8-10 months of age. The juvenile seahorses quickly adapt the characteristic of the adult Lined seahorse.  However, unhatched seahorses that have died will create a gas within the male's pouch. Soon after, the male seahorse inevitably floats to the surface, only to become easy prey in the marine food chain. 
A unique characteristic of the H. erectusis that the species practices monogamy: the male and female seahorses choose partners that they will continue to mate with for their lifetime.  The monogamous characteristics of the Lined seahorse include ritual dances with their partner that they perform every morning. These dances establish their permanent relationship as mates. If a male or female Lined seahorse should lose their partner for any reason, it takes time before they replace their mate. 
The Lined seahorses are weak swimmers; hence why they use their snouts to suck in their prey--they are not quick enough to hunt or chase after their prey. The Lined seahorses propel their bodies forward through their dorsal and pectoral fins, which they move rapidly back and forth. 
In addition to monogamy, the Lined seahorse also cues into sound-making. The seahorses have a crown-like bony crest called a coronet located on the backside of their head, at the edge of the skull. The coronet resembles a star pattern and is attached loosely. As a seahorse lifts its head, the edge of the skull slides beneath the coronet and out when the seahorse bows its head. As the skull's edge slides beneath and out from the coronet, a clicking sound occurs. Mating seahorses swim slowly together, alternating their clicking sounds, until they embrace one another; when this point is reached, the sounds from both the male and female unify, creating a louder, consecutive sound. 
The minimum tank requirements suggested for the Lined seahorse consist of a tank eighteen inches vertical in height and twenty to twenty five gallons for a pair, thirty to forty gallons for two pairs. The water temperature of the tank should be kept at a constant temperature somewhere between 72 and 77 degrees Fahrenheit (22 to 25 degrees Celsius).
- ^ Froese, R.; Pauly, D.. [www.fishbase.org/summary/speciessummary.php?id=3283 "Hippocampus erectus Perry, 1810 Lined Seahorse"]. FishBase. www.fishbase.org/summary/speciessummary.php?id=3283.
- ^ Rosamond Gifford Zoo Volunteers (July 23 2005). "Lined Seahorse". http://www.rosamondgiffordzoo.org/assets/uploads/animals/pdf/LinedSeahorse.pdf.
- ^ a b c [www.seahorsesource.com/erectus.html "H. erectus"]. Seahorse Source, Inc. 2005. www.seahorsesource.com/erectus.html.
- ^ a b c d e f Gardiner, Nick, University of Michigan. "Hippocampus erectus". Animal Diversity Web. http://animaldiversity.ummz.umich.edu/site/accounts/information/Hippocampus_erectus.html.
- ^ "Hippocampus erectus". IUCN Red List of Threatened Species Version 2011 Project Seahorse 2003. http://www.iucnredlist.org/apps/redlist/details/10066/0.
- ^ a b c d "Lined Seahorse". Chesapeake Bay Program (Bay Field Guide). http://www.chesapeakbay.net/bfg_lined_seahorse.aspx?menuitem=14400.
- ^ Project Seahorse Team". "Introduction to seahorses". Project Seahorse. http://seahorse.fisheries.ubc.ca/node/354.