Lined seahorse

Lined seahorse
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Conservation status
Vulnerable  (IUCN 3.1)
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Actinopterygii
Order:	Syngnathiformes
Family:	Syngnathidae
Genus:	Hippocampus
Species:	H. erectus
Binomial name
Hippocampus erectus Perry, 1810

The lined seahorse(Hippocampus erectus), northern seahorse or spotted seahorse is a species of fish that belongs to the Syngnathidae family.

Description

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 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.

This image shows the bony structure of the lined seahorse.

Habitat and distribution

The lined seahorse 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, Louisiana, 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.

Diet

The lined seahorse utilizes its elongated snout in order to consume its prey, consisting primarily of minute crustaceans. The seahorse sucks its prey through its tubular snouts. The lined seahorse is highly accurate if its prey is within one inch from its snout. A growing hippocampus erectus may feed continuously for up to ten hours a day, engulfing approximately 3,600 baby brine shrimp. In order to capture its prey, the seahorse employs color changes to camouflage itself with its surrounding environment.

Reproduction

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 develop 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.

Behavior

A unique characteristic of the lined seahorse (and other species of seahorse) is their practice of 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.

Lined seahorses are weak swimmers; hence why they use their snouts to suck in their prey since they are not speedy enough to hunt or chase. The lined seahorse propels its body forward with dorsal and pectoral fins, which they move rapidly back and forth.

In addition to monogamy, the lined seahorse also cues into sound-making in the mating process. 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 rather loosely. As the 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 is produced. Mating seahorses swim slowly together, alternating their clicking sounds, until they embrace one another. Once the male and female seahorse embrace, the sounds from both the male and female unify, becoming indistinguishable from one another. This action creates a louder, consecutive sound, further establishing their bond.

Aquarium life

The lined seahorse in an aquarium. Here, the natural habitat and vegetation of the H. erectus is mimicked.

The minimum habitat requirements for captive lined seahorses consist of a tank 18 inches vertical in height and 20 to 25 gallons for a pair, 30 to 40 gallons for two pairs. The tank should be kept at a constant temperature between 22 and 25 degrees Celsius (72 and 77 degrees Fahrenheit).