Great seahorse (Hippocampus kelloggi)

Classification (WoRMS)

Full classification as recorded by WoRMS: Kingdom: Animalia · Phylum: Chordata · Class: Teleostei · Order: Syngnathiformes · Family: Syngnathidae · Genus: Hippocampus.

Accepted name: Hippocampus kelloggi · Authority: Jordan & Snyder, 1901 · Taxonomic status: accepted · AphiaID: 212236.

Synonyms and superseded combinations recorded for this taxon: Hippocampus suezensis Duncker, 1940.

Source: World Register of Marine Species (WoRMS) — https://www.marinespecies.org/aphia.php?p=taxdetails&id=212236 (CC BY 4.0). Accessed 2026-09-23.

Biology and life history (FishBase)

Measured values published by FishBase for Hippocampus kelloggi. Only fields the database actually holds for this species are shown; these are database values, not aquarium guidance.

Maximum length: 28 cm · Depth range: 1–150 m · Habitat zone: bathydemersal · Body shape: other · Vulnerability index: 10 of 100 · Aquarium trade: never/rarely.

FishBase notes: Deep water species, associated with corals (Ref. 52034). Ovoviviparous (Ref. 205). The male carries the eggs in a brood pouch which is found under the tail (Ref. 205).

Source: FishBase species summary (SpecCode 53815) — https://www.fishbase.se/summary/Hippocampus-kelloggi.html (CC BY-NC 3.0 — non-commercial use only). Accessed 2026-09-23.

Distribution and occurrence records (GBIF)

210 georeferenced occurrence records for Hippocampus kelloggi are published through GBIF from 18 countries or marine areas. The map above plots 46 distinct locations from a sample of 210 records, omitting 22 inland records that carry an institution's coordinates rather than a collection site; it shows where the species has been observed and reported, not a modelled range.

Most records by country or area: China (88); Australia (33); New Caledonia (20); Japan (15); Philippines (13); Indonesia (12); Chinese Taipei (8); Malaysia (3); Oman (3); Thailand (3); Vanuatu (3); United Arab Emirates (2); Papua New Guinea (2); India (1); Jordan (1).

Marine regions with a valid WoRMS distribution record: Tanzanian Exclusive Economic Zone.

Source: GBIF Occurrence Search (taxonKey 5201145) — https://www.gbif.org/occurrence/search?taxon_key=5201145&has_coordinate=true (records CC0 / CC BY); WoRMS distribution records (MarineRegions) — https://www.marinespecies.org/aphia.php?p=taxdetails&id=212236 (CC BY 4.0); Natural Earth 110m basemap — https://www.naturalearthdata.com/ (public domain). Accessed 2026-09-23.

Conservation status (IUCN Red List)

The IUCN Red List assesses Hippocampus kelloggi Jordan & Snyder, 1901 as Vulnerable (code VU). No trend, population estimate or threat analysis is given here, because none is available from this source without the Red List API; follow the source link for the full assessment, including its date.

Source: IUCN Red List of Threatened Species (taxon 41010) — https://www.iucnredlist.org/species/41010/0; GBIF IUCN Red List category endpoint (taxonKey 5201145) — https://api.gbif.org/v1/species/5201145/iucnRedListCategory. Accessed 2026-09-23.

Description and natural history (Wikipedia)

It is found in the Indo-pacific region, specifically documented from the coast of East Africa to Japan. It was also recently identified around both northern and southern Australia. They frequent areas with an abundance of coral so they can latch on to something. Though often found in shallow waters, they have been recorded in depths of over 100 meters, with the deepest recorded seahorse at 152 meters below the surface.

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The head of the seahorse resembles a crown. Its spine is very prevalent, but has a rounded shape, especially above its eye. It is often confused for other species, and some great seahorses have even been thought to be an entirely new species, but gene sequencing has disproved this. They can be identified through their abnormally high tail rings on their comparatively slightly longer tails, which account for about 57% of their bodies. It is pale in color and smooth to the touch. They live for two to four years in the wild.

Males breed the eggs in sacks. Gestation lasts a few weeks, then males will release the eggs without caring for them. Generally, males are ready to breed again almost immediately after giving birth. Though little is known about the great seahorse's specific breeding habits, many related seahorses have been studied and were found to occasionally be monogamous. Their mating ritual involves twisting their tails and head nods, until they find a partner. Though the males carry the unborn young, they are also the main competitors for mates, which may have to do with an uneven ratio of males to females in a population.

Because the occurrence of the seahorse spans such a wide area, there is little data available regarding the size of the population, but it has been observed less in recent years, leading scientists to believe that the population is declining. There was a 50-60% decline in population size around Asia. It is generally found alone or in very sparse groups. It is considered vulnerable, which is one classification away from endangerment.

Like many other species of seahorse, the great seahorse is used both medicinally and for aquariums. It's one of the harder types to purchase and care for, as it is large and does not compete well with others for food, often resulting in early death. One of the major reasons the great seahorse is removed from captivity is due to its medicinal effects in China and other east Asian countries. It is said to help with problems such as impotence, and its prevalence on the market has increased in recent years. Aside from personal aquariums and medicine, the great seahorse is also used as a souvenir, often available dried for people to take home. The combination of these three has led the great seahorse to be labeled as vulnerable.

The specific name honours the American entomologist and evolutionary biologist Vernon Lyman Kellogg 1867-1937.

Source: Wikipedia: Great seahorse — https://en.wikipedia.org/wiki/Great_seahorse (CC BY-SA 4.0). Accessed 2026-09-23.