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Marine Animal Encyclopedia

Longsnout Seahorse Hippocampus reidi


Species ID: S.HR

Description: The seahorse’s elongated body is covered in bony armour and is characterized by a curving neck and horse-like head, as well as a curled prehensile tail. Body colour is variable, and can be yellow, white, brown, black or even two-toned. The body is peppered with small dark spots, distinguishing it from other seahorses. Males have a smooth pouch on their belly, while females do not. Juveniles resemble adults

Maximum Size: 18 cm (7 in) with the tail outstretched

Longevity: Unknown, but likely to be at least 4-5 years based on the longevity of relatives

Status: Insufficient information is currently available to assess the conservation status of this species according to IUCN standards, however, all seahorses are considered threatened and their trade is therefore controlled by CITES.

Long-Snout Seahorse & People: This seahorse is very popular in the aquarium trade, and collection of wild specimens still occurs. They are also dried for sale as tourist souvenirs or for export to Asia where they are used in traditional medicine


Geographical Range: The range of this species is still under review, but is believed to occur throughout the Caribbean and Gulf of Mexico, north to Florida and south to Brazil

Coral Reef Zone: These seahorses are found in the shore, back reef, and fore reef and drop-off zones

Favourite Habitat: Seahorses prefer shallow areas where they can camouflage themselves among seagrasses, algae, gorgonians, or sponges

Depth Range : 0 –55 m (0–180 ft)

A Day in the Life:

Dawn: Mated pairs perform greeting dances, and feeding activity begins

Day: Seahorses are most active during the day, when they feed and mate

Dusk: Some feeding activity occurs, but declines as the sun sets

Night: These seahorses rest at night while clinging to plants, sponges or gorgonians

Who Eats Who

The long-snout seahorse is a carnivore that eats tiny zooplankton, mysid shrimp and small crustaceans. They have few predators due to their armour and excellent camouflage, but are still eaten by rays, turtles, and especially crabs when young and vulnerable.

Scuba Diver & Snorkeler Best Practices

Remove only recent garbage from the sea Garbage that has been in the sea for a long time might have been adopted as a new home by some marine organisms; encrusting organisms may also call it home. Remove only recent garbage from the sea.


The hardest part about observing seahorses is finding one in the first place – they are masters of camouflage and so are very difficult to spot! Once located however, seahorses are easy to approach and observe because as they are slow swimmers and seldom flee from threats.

Feeding Behaviour

Long-snout seahorses feed passively on tiny planktonic creatures during the day, with some feeding during dawn and dusk. Their preferred feeding strategy is to remain camouflaged and ambush their prey while they hold on to a plant or coral with their flexible tails. Seahorses have eyes that can look in different directions at the same time, helping them locate their tiny prey, drifting in the ocean’s currents. Seahorses have no teeth so they swallow their food whole. They flick their head forward as they suck up prey through their tube-like mouth. A distinct clicking sound made by the jaws may also be heard as they feed. Although seahorses feed mainly by ambushing their prey, they sometimes leave their hiding spot to search for and chase prey – a behaviour common in areas where there is little vegetation.

Observe, record & share:

O S.HR-101 – Ambushing prey: Long-snout seahorses sway back and forth, moving each eye independently, as they search for suitable food in the plankton

O S.HR-102 – Sucking up prey: Seahorses raise and lower their head as they suck up prey

O S.HR-103 – Feeding clicks: The movement of a long-snout seahorse’s jaws produces a distinctive clicking sound audible to divers and snorkelers

O S.HR-104 – Hunting prey: Long-snout seahorses have been seen actively chasing planktonic prey

Attack & Defence Behaviour

Long-snout seahorses rely on their specially shaped bony armour and excellent camouflage abilities as their primary defence against predators. A seahorse’s ability to change colour, and the algae that often grows on its body, make it very difficult for predators to find. If threatened, a seahorse’s most common reaction is to lower its head and turn away from the threat. Although seahorses are not territorial, males will aggressively defend their mates against bachelors. A defending male will wrap his tail around his opponent’s tail and attempt to overpower him. If neither backs down, they may come to blows, consisting of an aggressive head-butt! The weaker seahorse usually swims away, especially after being struck, but if the attacker does not release him he will often darken and attempt to lie flat against the sand to signal submission, which ends the battle immediately.

Observe, record & share:

O S.HR-201 – Camouflage: Seahorses cling to a surface and often change colour to blend in

O S.HR-202 – Defensive posture: A threatened long-snout seahorse may lower its head and turn its back on a potential threat

O S.HR-203 – Tail-wrestling: During an encounter, seahorses grasp each other’s tails

O S.HR-204 – Head-butting: A fighting male may snap his head forward, striking an opponent with his snout

O S.HR-205 – Submissive pose: A seahorse defeated by a stronger opponent will darken and lie flat against the sand to indicate submission

Reproductive Behaviour

Seahorses have one of the most fascinating reproductive strategies on the planet. Amazingly, it is the male of the species, rather than the female, that becomes pregnant. Seahorses are monogamous and stay with their partner for many seasons, perhaps even for life. Pairs use their tails to cling to each other, and sometimes swim together in circles in a behaviour known as carouseling that is believed to reenforce the pair bond and accelerate mating. When the couple is ready to breed, the male courts the female for several days by changing colour, circling her, and flexing his body and pouch to show her that he is a strong mate with an empty egg pouch. In the final minutes of courtship, the two seahorses rise together, with the female pressing her belly against that of the male to deposit her eggs. The male fertilizes these eggs immediately and nurtures the developing embryos for roughly 14 days. When they are ready to hatch, the male goes into labour and jackknifes his body during violent contractions that push as many as 1500 young into the world, only a few of which survive to become adults. The seahorse breeding season lasts about 8 months – generally from February to October. The seahorse pairs breed repeatedly during this time; just as soon as the male has given birth he will begin courtship again.

Observe, record & share:

O S.HR-301 – Tail-holding: Seahorse pairs hold each other’s tails

O S.HR-302 – Carouseling: Seahorses pairs circle around each other, often in the early morning

OS.HR-303 – Male colour change: Males impress females with a series of colour changes

O S.HR-304 – Pouch pumping: Males rapidly bend and unbend their body, flexing the brood pouch, to impress females

O S.HR-305 – Egg transfer: The female presses up against the male’s pouch and transfers her eggs into it

O S.HR-306 – Labour and birth: Male seahorses push out their young in contractions

Highlight Behaviors

Courtship and mating: Seahorse reproduction is a fascinating and unusual behaviour. There are several distinct phases that divers and snorkelers can observe. In stage one, the male changes colour, and displays his brood pouch by bending and pumping water in and out of the pouch opening. In stage two, both partners dance together, intertwining their tails and quivering. In stage three, the female points her snout towards the surface, while the male continues his pouch pumping display. Both partners rise together through the water column and the female presses her belly against that of the male to deposit her eggs into his brood pouch.

Did You Know?

• The skin of many seahorses contains certain carbohydrates, or sugars, that encourage the growth of algae on their bodies, thus improving their camouflage abilities.

• Nearly 25 million seahorses are traded worldwide each year. Because of its large size and bright colours, the long-snout seahorse is one of the most heavily traded seahorse species in the world. The huge volume of trade in seahorses has conservationists worried that they may soon become endangered.

What to do?

Share your observations today!: Discover your species of interest, observe its behaviour, and share your pictures and videos with friends and coral reef enthusiasts around the world! Upload media to the web, tagged with species common name (ex.: trumpetfish) and species ID code (ex.: A.AM) or species behaviour code (ex.: A.AM-101)

Longsnout Seahorsezoom image
  • Order Syngnathidae
  • Length 18 cm (7 in)
  • Weight Not recorded
  • Depth 0 –55 m (0–180 ft)
  • Habitat Shore zone, back reef, fore reef and drop off zones
  • Distribution Found throughout the Caribbean and Gulf of Mexico, north to Florida and south to Brazil
Longsnout Seahorse habitat mapzoom image