Different Types Of Seahorse Species: The 8 Most Extreme

Currently, there exist 47 different types of seahorses in the world. We reveal 8 unique seahorse species with various characteristics that contribute to their enchanting and captivating nature.

The rarest.
Knysna seahorse

A rare photo of the Knysna seahorse
A species only found in South Africa | Photo: Bevis Chin

The Knysna seahorse is the worlds most elusive and endangered seahorse. This species is only found across three fragmented, local estuaries on the south coast of South Africa.

Threatened with extinction and is now totally protected by law. The Knysna seahorse is the best known of the five species that are believed to inhabit South African waters. Recorded only in The Knysna Keurboom and Swartvlei estuaries on the south coast, where it inhabits shallow eelgrass beds.

The threat of pollution, disturbance and poaching combined with their limited range puts this species at an even greater risk of extinction.

Scientific Name Hippocampus capensis
Common Names Knysna or Cape seahorse
Size 4.7 inches (12 cm)
Habitat South Africa
Status Endangered

The smallest.
Satomi's pygmy seahorse

Floating macro photo of the Satomis pygmy seahorse
Satomi’s pygmy seahorse is one of the hardest species to find, let alone photograph.

The record for the world's smallest species of seahorse goes to the Satomi's pygmy seahorse, which as an adult has an average length of only 13.8 millimetres (little bigger than a grain of rice), and an approximate height of 11.5 millimetres.

Formally described as a new species in 2008, and was named in honour of Miss Satomi Onishi, the dive guide who collected the type specimens.

Satomi's pygmy seahorses are known only from a few localities in Indonesia including, Derawan Island, off Kalimantan (Indonesian Borneo) and Raja Ampat (West Papua).

It’s understandable how they went undetected for so long. Not only are they known to be incredibly elusive during the day, but being the smallest seahorse (like other pygmy seahorses) its size and camouflage also make it extremely tough to spot.

This species can be identified by their small size, a small black dot between the eye and the snout as well as orange filaments and markings on the back, tail and chin.

Pygmy seahorses have among the smallest home range of any fish, venturing not further than 6-7 inches each day.

Scientific Name Hippocampus satomiae
Common Names Satomi's pygmy seahorse
Size 0.54 inches (13.8 mm)
Habitat Indonesia
Status Unknown

The biggest.
Big-belly seahorse

Mating male and female Big Belly Seahorse's
Big-belly seahorses mate as they float together in harmony

Big-belly seahorses, which can grow to a maximum length of 35 cm are the largest seahorse species in the world.

They are found in the temperate marine waters around southeastern Australia and around New Zealand where they inhabit harbours and sheltered coastal bays. Considered rare at most locations, but they are easily recognised by their large stomachs.

Big-belly seahorses come in wide range of colors, ranging from brown, greyish-yellow, orange to white, or mottled with dark spots on their entire body, except for the belly. Their coloring allows them to blend into seagrasses and weeds.

Their diet consists of Marine plankton, especially small crustaceans such as Copepods and Amphipods. As adults, due to their size, they become easier prey to larger animals like crabs, octopus, and larger fish like stingrays and manta rays.

Scientific Name Hippocampus abdominalis
Common Names Big-belly or pot-bellied seahorse
Size 13.8 inches (35 cm)
Habitat Australia, New Zealand, South Pacific, West Pacific
Status Least concern

The most common.
Yellow seahorse

Photo of the common yellow seahorse
A male yellow seahorse (Hippocampus kuda)

The yellow seahorse inhabits a widespread area with approximately 23 countries confirming the native presence of this species.

They are very commonly encountered in Indonesia and New Guinea but can also been found in waters from the Persian Gulf to Southeast Asia, Australia, Pakistan, India to southern Japan, and some of the Pacific islands, including Hawaii. Variations of this species also reside in other areas outside of the Indo-Pacific region.

Yellow seahorses come in a variety of colors, the females often have some yellow and dark spots on their bodies, but the males are usually a bit grayer with dark spots. Their bodies are quite smooth compared to other species of seahorses, with no spines and a thick snout.

Although this species is still commonly found, their captive distribution has become global as they are very popular as ornamental aquarium fish. However, incidental capture in shrimp trawl fisheries and habitat degradation and exploitation are the main threats to this species.

Scientific Name Hippocampus kuda
Common Names Common, spotted, yellow, estuary or Vietnamese seahorse
Size 11.8 inches (30 cm)
Habitat Indo-Pacific
Status Vulnerable

The strangest.
Leafy seadragon

Night photo of the leafy seadragon
Their plant-like appearance allows them to perfectly blend in with algae

The leafy seadragon has to be one of the the most ornately decorated marine animals on our planet.

As their name implies, leafy seadragons look like they have leaves attached to their bodies. But the leaf-like structures are not used for swimming, instead these leaf-shaped appendages which cover their entire bodies, give themselves almost flawless camouflage in seaweed and the kelp formations they live amongst.

To move, this strange species uses two fins, one pectoral and one dorsal, which are so thin they are almost transparent.

Leafies are endemic to the ocean around Southern Australia, found only from Wilson’s Promontory in Victoria in the east, west to Jurien Bay, 140 miles (220 km) north of Perth in Western Australia.

They inhabit temperate waters, usually between 13 to 50 feet deep (4 to 15 m). Once you’ve spotted one, don’t worry about losing it — they move only about 1/8 of a mile (200 m) per hour.

Scientific Name Phycodurus eques
Common Names Leafy or Glauert's seadragon
Size 13.8 inches (35 cm)
Habitat South & East Australia
Status Least concern

The most beautiful.
Zebra seahorse

It's subjective but the zebra seahorse is known for its uniquely appealing appearance | Photo: Denise Nielsen Tackett

The zebra seahorse is a rare but beautiful sight. As its name suggest, this tropical seahorse has alternating pale and dark zebra-like bands and stripes on the head and body, and often yellow tips on the spines.

The species was first described in 1964 and relatively little is known about the species.

It is endemic to northern Australia but can also be found in Papua New Guinea and Indonesia. They often reside inshore in and around coral reefs and can also be found in areas with sand and muddy bottoms.

Scientific Name Hippocampus zebra
Common Names Zebra seahorse
Size 3.1 inches (8 cm)
Habitat Northern Australia, Papua New Guinea, Indonesia
Status Unknown

The most camouflaged.
Bargibanti pygmy seahorse

Bargibanti pygmy seahorse camouflaged on gorgonian coral
Likely one of the most commonly photographed seahorse species

The Bargibanti’s pygmy seahorse was the first species of pygmy seahorse to be discovered and is arguably one of the cutest animals in the oceans.

Discovered in 1969 near New Caledonia by Georges Bargibant, a marine biologist who noticed a pair of tiny seahorses on his dissection table whilst examining a collection of gorgonian sea fan corals.

The Bargibant’s pygmy seahorse is is a master of camouflage and extremely difficult to spot amongst the gorgonian coral it inhabits for their entire lives.

Adults are usually found in pairs or clusters of pairs, with up to 28 pygmy seahorses recorded on a single gorgonian. They reside at depths of 52.5 to 131 feet (16-40 m) and live exclusively on gorgonian corals of the genus Muricella.

These pygmies have be found all the way from Japan, Indonesia and the Philippines to northern Australia, Papua New Guinea, Solomon Islands and Fiji.

They are one of the most commonly observed, and photographed species by scuba divers – a great macro camera is certainly needed. However great care must taken as these fragile creatures have no eyelids, therefore extremely sensitive to bright lights, such as torches and camera strobes.

Scientific Name Hippocampus bargibanti
Common Names Pygmy, Bargibanti or gorgonian seahorse
Size 0.79 inches (2 cm)
Habitat Central Indo-Pacific
Status Vulnerbable

The most prickly.
Spiny seahorse

Night photo of the spiny seahorse species
The spiny seahorse is also referred to as the thorny or spiny seahorse | Photo: Claudio Ceresi

The spiny seahorse, known for its distinctive dark tipped spines and long, tapered snout, made its first recorded appearance in Maui in the 1920s.

This sometimes pelagic species usually favors relatively deep waters and is commonly found below 15 m depths. Residing mainly on seagrass beds but also sponges and soft corals.

Spiny seahorses have be reported in Australia, Indonesia, Papua New Guinea, New Caledonia and Japan.

Scientific Name Hippocampus histrix
Common Names Spiny, longspine or thorny seahorse
Size 6.7 inches (17 cm)
Habitat Indo-Pacific
Status Vulnerable

How to tell them apart

Seahorse species share common characteristics such as their upright body posture, horselike head, independently moving eyes, prehensile tail, and unique reproductive behavior where males carry the fertilized eggs in a brood pouch. Here's some of the ways you can tell them apart:

different types of seahorse infographic
Seahorses belong to the genus Hippocampus and are divided into several main types or species. This infographic shows some of the notable types of seahorses and their easily recognizable features.

How to determine the sex of a seahorse

Determining the sex of a seahorse can be challenging. One method is to observe the size and shape of the abdominal region. Males typically have a more pronounced and often pouch-like structure, while females have a smoother, flatter abdomen.

You heard it right, its the males who actually get pregnant and give birth.

The difference between pipefishes and seahorses

Pipefishes and seahorses are fascinating creatures that share certain similarities but also have distinct differences. Both belong to the same family, Syngnathidae, known for their unique appearance and reproductive behavior. However, there are notable contrasts between these two groups.

pipefish and seahorse together on black background
Gulf pipefish (left) and Tiger-tail seahorse (right)

Both the pipe fish and the seahorse have small, bonnie, narrow noses and a small fin on their back to help them swim. Although these interesting creatures are relatives, that share many similarities in appearance, behavior and habitat, there are some obvious differences.

Pipefishes, like seahorses, have elongated bodies and belong to the same taxonomic family. However, they lack the distinct horselike head and curled tail that seahorses are known for. Instead, pipefishes have a more elongated and tubular body shape, resembling a thin pipe or reed. They often have a straight or slightly curved snout, which distinguishes them from the snout of seahorses.

Another key difference between pipefishes and seahorses is the way they carry their eggs. While seahorses have a unique brood pouch on the male's belly, where the female deposits her eggs, pipefishes do not possess such a specialized pouch. Instead, pipefishes usually have a small adhesive pad or hooks on the belly where the female attaches her eggs externally.

Help save seahorses

Approximately twenty-one million seahorses are caught each year for private aquaria, curios and traditional Chinese medicines. Unfortunately their biology and natural habitat associations make them susceptible to decline.

The extinction of seahorses is predicted to occur over the next 20 years if no action is taken. To find out how you can help conservation efforts, visit Project Seahorse, an ocean conservation organization who are global leaders in saving seahorses.

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