The Japanese Pygmy Seahorse – Hippocampus sp.

The Japanese Pygmy Seahorse – Hippocampus sp.

The Japanese pygmy seahorse, Hippocampus sp, (known locally as 日本のピグミータツノオトシゴ or Japapigu) is an, as yet, undescribed species of true pygmy seahorse found, as the name suggests, in Japan.  They appear to be closely related to Coleman’s, Pontoh’s and Severn’s species, and like these other species, are not found living in close association with a specific host such as a gorgonian or soft coral.

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.  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 saw many in the 8-15 metre range in protected areas, where they were living amongst the algal turf and small hydroids.

Given that they are yet to receive a scientific name, it is unsurprising that very little is 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 work on the gorgonian-associated pygmy seahorses is the only research on these species’ biology yet to be carried out.

You can see some of my Japanese pygmy seahorses by following this link.

 

 

Japan Diving Trip Report

Japan Diving Trip Report

I have recently returned from an exceedingly fruitful trip to Japan, where I attended the 9th Indo-Pacific Fish Conference in Okinawa and dived both Izu Peninsula and Hachijo-jima.

Having initially spent a week in Okinawa, attending the conference I spent a week exploring Izu Peninsula organised by Kiki Diving Club, which are based in Nakano, Tokyo.  I visited a few different areas, the first being Arari Dive Centre on the west coast of Izu.  This was a great spot for muck diving.  I saw many Japanese pygmy pipehorses, tube blennies and nine different frogfish!

After Arari we headed to Osezaki, also on the west coast, and dived with Hamayuu Dive Centre for a couple of days.  I particularly liked the outside of the bay, where deepwater currents make for interesting diving beyond the 30m mark.  Here we saw small schools of Cherry (Sacura margaritacea) and striped anthias (Pseudanthias fasciatus), both found only in deep water.  Inside Osezaki bay is a proper muck dive, and very protected from currents and big seas.  It is also a very popular site for learner divers and there can apparently be 100’s of divers at the weekend, which I avoided like the plague!

Finally, Shingo (owner of Kiki Diving Club) and I visited Izu Oceanic Park on the east coast of the Izu peninsula.  This is also a popular site and the critters’ locations are well known to the management.  They passed on the info and we succeeded in finding a few frogfish and some Japanese endemics.  Unfortunately the swell picked up making entry/exit a bit of a nightmare, especially with a massive camera, so we just did two dives.

After Izu I headed, with a friend, to Hachijo-jima, an island nearly 300 kilometres south of Tokyo.  The diving was outstanding and thanks to Tanaka-san and Ogino-san of Concolor Diving I saw everything I had on my wish list.  The very top of the list was the undescribed Japanese pygmy seahorse, of which I ended up seeing thirteen!

We experienced some unseasonably cold water, at around 19˚C, which made some of the dives a little chilly!  By the end of the week though the water was back to normal and I’m informed a few days after it was back to the expected 28˚C, after the Kuroshio current shifted back to its rightful place.

All in all, my first experience of Japanese diving was exceptional, and I’m keen to get back there and explore a little more of what the country has to offer.

If you would like to see my images from this trip, follow these links to: Izu or Hachijo

 

Pygmy Seahorse Facts & Images

On the 1st April 2011 my PhD was officially awarded.  I am the first person to have completed a PhD on the biology of pygmy seahorses and I’m excited to share some of my findings.  My thesis is entitled ‘The Biology and Conservation of Gorgonian-Associated Pygmy Seahorses’.  I will be publishing the findings from my thesis in the scientific literature in the coming months so keep checking back or sign up to my blog updates for details.  Until then I wanted to share some information and facts about pygmy seahorses:

• What is a pygmy seahorse?

Pygmy seahorses are a group of seven species of miniature syngnathids (technical name for seahorses and pipefish) fish that live in the Coral Triangle region of southeast Asia. They range in length from 1.4 – 2.7 cm between the tip of the tail to the end of the snout.

• How many species of pygmy seahorse are there?

Within the first decade of the 21st century six of the present total of seven species of pygmy seahorse were officially named.  Before that only Bargibant’s pygmy seahorse was known to science, having been described in 1970.

Follow the links below to the image galleries for each of the pygmy seahorse species where there is more information about them individually:

Bargibant's Pygmy Seahorse (Hippocampus bargibanti)Bargibant’s pygmy seahorse (Hippocampus bargibanti)

 

 

 

 

Denise's pygmy Seahorse (Hippocampus denise)Denise’s pygmy seahorse (Hippocampus denise)

 

 

 

 

Pontoh's Pygmy Seahorse (Hippocampus pontohi)Pontoh’s pygmy seahorse (Hippocampus pontohi)

 

 

 

 

Satomi's Pygmy Seahorse (Hippocampus satomiae)Satomi’s pygmy seahorse (Hippocampus satomiae)

 

 

 

 

Severn's Pygmy Seahorse (Hippocampus severnsi)Severn’s pygmy seahorse (Hippocampus severnsi)

 

 

 

 

Walea Soft Coral Pygmy Seahorse (Hippocampus waleananus)Walea soft coral pygmy seahorse (Hippocampus waleananus)

 

 

 

The final described species of pygmy seahorse, Coleman’s pygmy seahorse (Hippocampus colemani), is thought to be restricted to Lord Howe Island off the east coast of Australia although there are unconfirmed reports from eastern Papua New Guinea and Taiwan.  I am yet to observe this species in the wild but hopefully one day I will have the opportunity!

There are likely to be new and undescribed species of pygmy seahorse yet to be discovered.  One such species that awaits a name is the Japanese pygmy seahorse.

Japanese pygmy seahorse (Hippocampus sp.)Japanese pygmy seahorse (Hippocampus sp.)

 

 

 

• How do pygmy seahorses differ from the larger seahorses?

Pygmy seahorses are morphologically distinct from all other seahorses.  Apart from their extremely small size, they have a single gill opening on the back of the head (all other seahorses have a pair of gill openings either side of the head) and the young are brooded within the male’s trunk rather than a pouch on the tail.

Several other small seahorses are sometimes referred to as pygmy seahorses, but lack the true pygmy’s single gill opening and trunk brooding.  These include some recently discovered species such as the endemic Red Sea soft coral pygmy seahorse (Hippocampus debelius) and a pair of deepwater, apparently closely related, southern Australian seahorses: the southeast Australian Bullneck seahorse (Hippocampus minotaur) and the southwestern Paradoxical seahorse (Hippocampus paradoxus).

• Where do pygmy seahorses live?

Pygmy seahorses live in different habitats from their larger cousins.  Larger seahorses are rarely found on tropical corals reefs, particularly current prone walls.  Pygmy seahorses have evolved several adaptations to fill this niche perfectly.

Three species of pygmy seahorse have evolved a special association with sessile coral reef invertebrates.  Two, Bargibant’s and Denise’s pygmy seahorses, are only found living on gorgonian corals.  Bargibant’s lives only on one genus of gorgonian coral, Muricella spp, whilst Denise’s pygmy seahorse is known from at least nine genera of gorgonians.  The third species, the Walea pygmy seahorse, is found living in association with soft corals.

• What do pygmy seahorses eat?

The diet of pygmy seahorses consists of small crustaceans.

• Can you distinguish between male and female pygmy seahorses?

Male pygmy seahorses have a tiny slit at the base of the abdomen and females have a tiny round, raised pore.

Distinguishing between male and female pygmy seahorses

Female pygmy seahorse on the left hand image (a) with a raised circular urinogenital pore and a male right (b) with a slit-like opening to the brood pouch.  Scale bars are 5 mm.

• How do pygmy seahorses reproduce?

Like all seahorses the male is responsible for all post-fertilisation care of the developing young.  Eggs are transferred, unfertilised, to him from his mate into his brood pouch.  They remain within the pouch, which is full of blood vessels, until they are born 11-14 days later.  The blood vessels bring nourishment and oxygen to the developing offspring.  Between 6 and 34 young have been recorded from a single clutch of eggs.

• What happens to the baby pygmy seahorses after they’re born?

The young are released with some force from the male’s brood pouch and are swept away by the current into the ocean.  They then have a planktonic phase where they feed and grow in the water column until settling onto the reef.  They are dark in colour until settling onto the reef, where they change to suit their immediate surroundings.

Satomi’s pygmy seahorse on the other hand, is reported to give birth to young that settle immediately to the reef around their parents.  This observation does however seem at odds with the relatively large geographic distribution of the species.  Without a pelagic phase for young pygmies to drift with ocean currents and reach new reefs they would be unlikely to have a distribution stretching from east to west Indonesia.

For more information on the birth of pygmy seahorses in the wild follow this link to my paper from the journal Coral Reefs.

• Are pygmy seahorses endangered?

Mine has been the first study on the population sizes of pygmy seahorses.  Currently all seven species of pygmy seahorse are classified as ‘Data Deficient’ by the IUCN World Conservation Union.  This classification means that not enough is known about their population sizes to make an informed assessment of their conservation requirements.

I studied the populations of Bargibant’s and Denise’s pygmy seahorses around Wakatobi Dive Resort, southeast Sulawesi, Indonesia.  The resort has gone to great lengths to protect their reefs for the last fifteen years, which provided a rare opportunity to estimate pygmy seahorse populations in a near pristine environment.  I found that the population sizes of these two pygmy seahorse species are naturally low.  They were in fact among the lowest for any unexploited seahorse population yet studied.  Their habitat specificity and small population sizes mean that conservation measures may need to be taken to protect them in some areas.

For more information on my pygmy seahorse population paper published in the scientific journal Marine Ecology Progress Series, please follow this link.

• Do pygmy seahorses have any predators?

The small size and amazing camouflage of pygmy seahorses mean they do not suffer heavy rates of predation.  Occasionally however, they may be opportunistically be taken by one of the reef’s general predators.  There are also reports of long-nose hawkfish eating pygmy seahorses but there is no truth to the myth that the presence of a hawkfish on a gorgonian means there will be no pygmies present.

• Can you keep pygmy seahorses as pets in an aquarium?

The habitat specialisation of pygmy seahorses, their extremely delicate nature and small size all prevent the true pygmy seahorses from being kept as pets in aquaria.  Unsuccessful attempts have been made by national aquaria in the past and resulted in the death of the animals and their gorgonian coral host. Confusion can arise as the Dwarf seahorse, Hippocampus zosterae, is also known as a pygmy seahorse.  Unlike the true pygmies, this species is slightly larger, has paired gill openings and males have a brood pouch located on the tail.  The care of these dwarf seahorses can be quite challenging and it is recommended only for experienced aquarists.

Sport Diving feature article – Togian Treasures

Sport Diving feature article – Togian Treasures

As part of my PhD research I visited a small resort in central Sulawesi.  It is scarcely known to non-Italians, but an absolute gem.  I was in search of the amazing Walea soft coral pygmy seahorse (Hippocampus waleananus), which is known only from the reefs of the Togian Islands.

The diving is outstanding, with some of the best hard coral I have seen and many interesting critters, including bumblebee shrimp, boxer crab, tiger shrimp, four species of pygmy seahorse and the rare Kyonemichthys rumengani found in abundance.

My article about the area is featured in the new issue (159) of Sport Diving magazine, available now throughout Australasia.


Attachment: TogianTreasures.pdf

Sport Diver Feature Article ‘Where Whale Sharks Roam’

Sport Diver Feature Article ‘Where Whale Sharks Roam’

Sport Diver UK have just published the July issue of their monthly magazine, which contains my article ‘Cenderawasih Bay; Where Whale Sharks Roam’.  This feature is about the month I spent aboard Dewi Nusantara in the mysterious and newly visited part of Indonesia on Papua’s north coast.

The absolute biggest, excuse the pun, draw here are the whale sharks that come to feed on donations given to them by local fishermen.  I, however, was equally excited by the plethora of endemic creatures that make Cenderawasih their home.  The article also delves into these other, lesser known, residents so check out the magazine in your local newsagent or the apple newsstand.

 

 

UltraMarine Magazine issue 40 – The Coral Triangle

UltraMarine Magazine issue 40 – The Coral Triangle

UltraMarine have just published their 40th issue, where I am please to have an article about the reefs of the Coral Triangle.  The countries of Indonesia, Philippines, Malaysia, Papua New Guinea, Solomon Islands and East Timor collectively make up the Coral Triangle, which is known as the centre of the world’s coral reef biodiversity.  It is a fascinating area to dive and I hope this article impassions people to experience it for themselves and the will to protect it.