Marine life  /  Seahorses & pipefish  /  Hedgehog seahorse
Reviewed 2026-09-06
Species entry

Hedgehog seahorse

Hippocampus spinosissimus

A stout seahorse with short sharp spines, on rubble and sponge rather than on soft coral.

Size
To 17 cm
Depth
10–40 m
Habitat
Rubble and sponge on sand
Active
Daylight
Range
Indo-Pacific
Rarity
Dauin & Dumaguete
5 stars of 5, a handful of records
SP-01
hedgehog seahorse · full body · habitat
4:3 · min 2400px

A seahorse to about 17 cm, heavier in the body than the common seahorse and armed with short sharp spines along the back and on the head, the coronet spines the longest of them. Colour runs from cream and pale yellow through mid-brown, usually with fine darker mottling and sometimes with pale saddles across the back. The snout is of medium length, shorter than the thorny seahorse’s and blunter, and the spines are shorter and stouter than that species’. Worn and older animals lose spine length, which makes the two harder to separate than the descriptions suggest.

It is a soft-bottom animal. Most records come from rubble, sponge and sand below about 10 m rather than from the shallow weed and coral where common and tigertail seahorses are found, and much of what is known about it comes from trawl bycatch rather than from divers. That also means it is met deeper than most seahorses on a muck slope, and usually as a single animal holding onto sponge or a lump of rubble rather than onto a holdfast a guide can return to.

The species is recorded across the Indo-West Pacific, with the Philippines and Indonesia well within its range. Like all seahorses it is listed on CITES Appendix II, and like the rest of the soft-bottom species it is taken in quantity as trawl bycatch, which is the main pressure on it.

Where to find:

LocationRarity Best monthsDepthHabitat
Dauin & Dumaguete Philippines editorial estimate
5 stars of 5, a handful of records
Year-round
10–40 m
Rubble and sponge on sand
Lembeh Strait Indonesia editorial estimate
5 stars of 5, a handful of records
Year-round
10–40 m
Rubble and sponge on silt
Anilao Philippines editorial estimate
5 stars of 5, a handful of records
Year-round
10–40 m
Sand, rubble and sponge
Ambon Indonesia editorial estimate
5 stars of 5, a handful of records
Year-round
10–40 m
Harbour rubble and sponge

Ratings are per location: 1 means found on most dives that look for it, 5 means a handful of records. Where enough dives have been logged the figure is calculated from them; otherwise it is an editorial estimate, and says so. We publish habitat and destination, not the dive site.

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