Supporting Seahorse Relatives

Seahorses, pipefishes, pipehorses and seadragons – about 300 fish species in the family Syngnathidae – are all subject to a similar array of pressures and conservation challenges.

As host of the IUCN’s global expert group on syngnathid fishes, the IUCN SSC Seahorse, Pipefish and Seadragon Specialist Group, Project Seahorse has a deep commitment to conservation initiatives for all species in the family. Our SPS SG also has responsibility to support conservation efforts for other near relatives: trumpetfishes (Aulostomidae), shrimpfishes (Centriscidae), cornetfishes (Fistulariidae) and ghost pipefishes (Solenostomidae).

Little known but very interesting

Our focus in this section is on the members of the family Syngnathidae, other than seahorses – the pipefishes, pipehorses, and seadragons. We know little to nothing about a great many of these species. Indeed, 76 (32%) of these species are so little understood that we can’t even assess their conservation status. Many species are, however, of public interest. Some pipefish species are sought as aquarium fishes for ornamental display. And all three seadragon species are fantastical species that astonish everybody who encounters them.

Fantastic forms

Pipefishes, pipehorses and seadragons all have very distinctive body shapes. Pipefishes are slender, elongated and linear fishes with adults that range from about 2 cm to 65 cm in length. Some have somewhat prehensile tails that wrap around holdfasts. Pipehorses have a body form that seems half way between that of pipefishes and that of seahorses; they are a less linear, with heads that bend about 45° to the body. The smaller pygmy pipehorses in the genus Acentronura have adults that measure 5 to 8 cm long whereas the larger pipehorses in the genus Solegnathus are between 30 to 50 cm long. Seadragons – which measure 25 to 45 cm as adults – are very particular in their shape and have spectacular long skin filaments and appendages trailing from their bodies.¹

A glimpse at ghosts

Ghost pipefishes are not syngnathids and are found in their own family, Solenostomidae, all in one genus Solenostomus with four species. They grow to about 15 cm and spend much of their time floating motionless with their heads down. Amazingly, these nearest relatives to the syngnathids provide parental care very differently; the female’s pelvic fins are fused to form a pouch external to her body, where she broods the embryos. They spend a long time floating as plankton before settling as adults on the reef.² Among the four ghost pipefish species, the IUCN Red List evaluates one as Data Deficient and three others as Least Concern.

[Updated 10 June 2021]