The lined seahorse typically reaches a length of five to seven inches, although they have been reported to be eight inches. In almost all cases, the males outgrow the females. The maximum reported age of the lined seahorse is one year.  They have a broad color spectrum, ranging from black, grey, brown, and green, to orange, red, and yellow. However, their colors may be altered 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, but only forwards in direction. Typically, the tail is curled forward; it is very seldom to find the tail 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 is considered "sexually mature" around eight months, although it has occurred as early as four 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 themselves with their surrounding environment.  
- ^ a b Froese, R.; Pauly, D.. [www.fishbase.org/summary/speciessummary.php?id=3283 "Hippocampus erectus Perry, 1810 Lined Seahorse"]. www.fishbase.org/summary/speciessummary.php?id=3283.
- ^ a b [www.seahorsesource.com/erectus.html "H. erectus"]. Seahorse Source, Inc. 2005. www.seahorsesource.com/erectus.html.
- ^ a b Gardiner, Nick, University of Michigan. "Hippocampus erectus". http://animaldiversity.ummz.umich.edu/site/accounts/information/Hippocampus_erectus.html.
- ^ "Hippocampus erectus". http://www.iucnredlist.org/apps/redlist/details/10066/0.
- ^ a b "Lined Seahorse". Chesapeake Bay Program (Bay Field Guide). http://www.chesapeakbay.net/bfg_lined_seahorse.aspx?menuitem=14400.