What do you think is the most exciting aspect of scuba diving? For me, it is passively observing all the amazing marine life that you find underwater. I have a particular soft spot for macro life as I love to see the strange ways these animals have evolved to survive. As a keen underwater photographer, macro subjects tend to be the easiest critters to consistently get great photos of. When it comes to macro life, you will struggle to find anything more macro than pygmy seahorses.
What is a Pygmy Seahorse?
The name says it all really: Pygmy seahorses are a group of very small seahorses. They are members of the syngnathid family, which includes larger seahorses and pipefish.
Pygmy Seahorse Size:
As the name “pygmy” implies, pygmy seahorses are tiny. Even the largest – the Hippocamus bargibanti- reaches a maximum size of 2.7 centimetres from tail to snout, while the smallest – the Hippocampus satomiae- has an average length of just under 1.4 centimetres.
How Many Species of Pygmy Seahorses are there?
Due to the tiny size and superb camouflage of pygmy seahorses, they are notoriously difficult to spot. At the beginning of the millennium, only the Hippocampus bargibanti has been discovered. By the year 2010 a further six species had been described, however recently one of those lost their status as a unique species and has been merged with another species.
The currently described species are as follows:
- Hippocampus bargibanti – Bargibant’s pygmy seahorse – named in 1970
- Hippocampus denise – Denise’s pygmy seahorse – described in 2003
- Hippocampus pontohi – Pontoh’s pygmy seahorse – named in 2008
- Hippocampus satomiae – Satomi’s pygmy seahorse – named in 2008
- Hippocampus waleananus – Walea soft coral pygmy seahorse – named in 2008
- Hippocampus colemani – Colmans’s pygmy seahorse – described in 2003
The species previously known as Severn’s pygmy seahorse has recently been merged into Pontoh’s pygmy seahorse, as tests proved it was the same species with a different colouration – although many fish identification books still have it as a separate species. In 2016, the two species Hippocampus waleananus and Hippocampus satomiae were also merged into one species, however the leading authority on pygmy seahorses, Dr Richard Smith, of Ocean Realm Images believes this to be a mistake due to poor testing.
There is also a further species of pygmy seahorse that is yet to be officially described. The species can be found living in the south of Japan, and is currently known as the Japanese pygmy seahorse.
Pygmy Seahorse Habitat
Unlike larger seahorses, which prefer to live in shallow, sheltered sandy bays where currents are weak, pygmy seahorses have adapted to live on coral reefs, especially those prone to strong currents.
Two species – Bargibant’s and Denise’s pygmy seahorse – have evolved to only live on gorgonian corals, and one species – the Walea pygmy seahorse – lives in association with soft corals. These host species require water movement to be able to feed, so only successfully live in areas prone to current. These pygmy seahorses will spend their entire life on their host, and will usually live in an area less than the size of a dinner plate.
The other species are free living, which means they do not require a host coral to live on. This makes them even harder to spot, as they could be anywhere! Although they can roam around the reef, they tend to stay roughly in the same area for an extended period of time.
What does a Pygmy Seahorse eat?
Like their larger cousins, pygmy seahorses are carnivorous and feed on a diet that consists of small crustaceans, such as young brine shrimp. They need to feed almost constantly as pygmy seahorse do not have a stomach, which means food passes through their digestive system very quickly. Pygmy seahorses spend most of their life either resting, feeding or breeding.
Pygmy Seahorse Reproduction
Like all other species of seahorse and true pipefish, it is the male who is responsible for the care and development of the young. The female will deposit unfertilised eggs into his brood pouch where the eggs will be fertilised. The males brood pouch is packed full of blood vessels which bring oxygen and food to the young, and roughly two weeks after him receiving the eggs, he will give birth.
The male gives birth with some force, expelling the young pygmy seahorses into open waters where they will be swept away with the currents. They will spend the first part of their lives in a planktonic phases, where they will feed and grow until they are large and strong enough to settle on a reef.
Although it may seem strange to us, there are numerous benefits to male pregnancy. One of which is that while the male is developing the young, the female can focus on developing more eggs, so once the male has given birth, the female is already ready to deposit her eggs.
Where can I Dive with Pygmy Seahorses
Pygmy seahorses can be found living throughout most of the coral triangle – a roughly triangular area that covers parts of Indonesia, Malaysia, The Philippines, Papua New-Guinea, Timor-Leste, and the Salomon Islands. There is also one species living in southern Japan, and you can find some living in the north of Australia.
While pygmy seahorses have quite a wide range, their miniature size makes them especially difficult to spot. An excellent dive guide is required, and you need to have a keen eye to know what you are looking at. A diving magnifying glass can help for those who have a tough time seeing macro life.
The best places to easily see pygmy seahorses is parts of Indonesia such as Bali, North Sulawesi, Wakatobi (South Sulawesi) and Raja Ampat (Western Papua). In these areas you will have the best local dive guides who could easily find a needle in ten haystacks.
How to Behave around Pygmy Seahorses
Their miniature size and impressive camouflage makes pygmy seahorse a hit amongst all divers, and especially photographers.
Great care must be taken to no touch or disturb either the pygmy seahorse or its host coral. They can die if they get too stressed, and their small size means even the lightest touch could kill them.
Pygmy seahorses have no eyelids, and the reefs they live on are much darker than the world we live in. You should never use a bright torch or camera focus light on them, as this will disorientate and stress them. If you are a photographer using an external strobe or camera flash, you should limit yourself to no more than five photos per pygmy seahorse or sea fan.
As they tend to be found in areas prone to current or water movement, extra care must be taken when watching them, especially those living on host corals, as the water movement could accidently push you into the host.
Are Pygmy Seahorses Endangered?
Currently all species of pygmy seahorses are classed as ‘Data Deficient’ by the World Conservation Union, which means not enough is known about the population size to properly classify them. Their tiny size and host requirements mean they could be at risk if measures are not taken to protect them or the sea fans some of them live on.
Luckily, because of their amazing camouflage, pygmy seahorses are rarely preyed upon, although if an opportunistic fish spots one it might take advantage of the situation.
Pygmy seahorses do not bode well in captivity as they are extremely difficult to keep alive. There have been cases where aquarium keepers have tried to keep Bargibant’s pygmy seahorse in a tank, however both the seahorse and the host gorgonian died. Although very difficult to find, it is possible to find pygmy seahorse for sale online, however do to the difficulty of keeping them alive, you should never purchase one.
3 Cool Pygmy Seahorse Facts:
1. Pygmy seahorses differ from their larger cousins as they only have one gill opening instead of two, and the brood pouch is found within a body cavity on their trunk rather than on the tail.
2. The Denise pygmy seahorse has the smallest range of any fish, spending all of its adult life in an area the size of a CD.
3. The first discovered pygmy seahorse – the Hippocamus bargibanti – was found by accident when a gorgonian coral was taken from the reef for testing. When examined closely, scientists discovered the tiny seahorses attached to it.
If you want to dive with these beautiful critters, then you are in luck! If you have dived with pygmy seahorses before, we would love to hear about it.. Let us know where your dive was and what species you saw in the comments section below!
Photo Credit: http://oceanrealmimages.com/pygmy-seahorses/species
‘The Life of a Pygmy Seahorse’ was written by Mike