Japanese Pygmy Seahorse Hippocampus japapigu

Japanese pygmy seahorse (Hippocampus japapigu)

The Japanese pygmy seahorse, Hippocampus japapigu, (known locally as 日本のピグミータツノオトシゴ or Japapigu) is a newly described species of pygmy seahorse found, as the name suggests, in Japan.  They are not found living in close association with a specific host such as a gorgonian or soft coral, rather they cling to algal turfs in the subtropical reefs on which they live.

I’m so pleased that this project naming the Japanese pygmy has finally come to fruition. It all began over a decade ago when I first saw a picture of an unusual pygmy seahorse from Japan. In 2013, after completing my PhD on the biology of their cousins the Bargibant’s and Denise’s pygmies, I went to a fish biology conference in Okinawa, Japan primarily with the goal of adding on a trip afterwards to hunt for the elusive fish. I found a dozen of them, when I took many of these images and made early field observations. Jumping forward to a seahorse biology conference in Tampa, Florida, for my involvement with the IUCN Seahorse, Pipefish and Stickleback Specialist Group, I met Graham Short and told him about the seahorse.  Along with some colleagues, our official description was released in August 2018 (link below).

The species is characterised, and distinguished from the other free-living pygmies, by a reticulate pattern of white lattice over the body, which often has a black spot within it.  There are also several morphological and genetic differences between this and other pygmy seahorses.  The body colouration is brown, beige, to pink and whitish.

They inhabit subtropical and temperate reefs from southern to the central west of Japan.  The Izu islands of Miyake and Hachijo are good locations to find these elusive seahorses, as well as Kushimoto and Sagami Bay.  I have seen many in the 8-15 metre range in protected areas, where they were living amongst the algal turf and small hydroids.

Beyond our work naming this species in 2018, there is very little known about their biology or conservation.  This is true of all the free-living pygmy seahorses, which are yet to receive a research focus.  My PhD work on the gorgonian-associated pygmy seahorses is the only research on these species’ biology yet to be carried out.

– Along with some colleagues, I published the scientific description (formal naming) of this species in August 2018:

Short G, Smith R, Motomura H, Harasti D, Hamilton H (2018) Hippocampus japapigu, a new species of pygmy seahorse from Japan, with a redescription of H. pontohi (Teleostei, Syngnathidae). ZooKeys 779: 27-49. https://doi.org/10.3897/zookeys.779.24799

My new book ‘The World Beneath‘ includes a chapter about my pygmy seahorse research and much more about the Japanese pygmy seahorse. MORE HERE

WoRMS’ Top 10 Marine Species (2018)
Hippocampus japapigu listed among the Top 10 new species of 2018 by World Register of Marine Species WoRMS

National Geographic article on H. japapigu discovery: ‘This colourful new seahorse is the size of a grain of rice