The first of the species to be named was Bargibant's seahorse (Hippocampus bargibanti), otherwise known as the Pygmy seahorse and the main focus of this feature. It is rare to find an example more than two centimeters in length, so they are difficult to spot. Add the fact that they have adapted to resemble the sea fans (closely related to coral) upon which they live in the western central Pacific Ocean (known as the Coral Triangle region of southeast Asia) and it seems hardly a surprise that they were overlooked for so long.
The sea fan that the pygmy seahorse calls home is otherwise known as a gorgonian. It is a testament to the ability of the pygmy seahorse to conceal itself that it was not spotted in the wild. In the early 1970s scientists studying gorgonians collected specimens to examine. Imagine their surprise when back in the lab something stared right back at them.
The pygmy comes in two known color variations. The first is a grey color with red tubercles – the nodules that you can see on this extraordinary fish. The second type is yellow with orange tubercles. Although it is not known exactly why these color variations occur the best guess (and one would imagine the correct one) so far is that they are specifically linked to the host gorgonian upon which the seahorses settle as adults.
Although some species other than the seven are referred to as pygmy, the true pygmy seahorses are distinctly different from others in terms of their morphology (the form and structure of organisms). Other seahorse species have two gills, one on each side of their heads. The pygmy has just a single gill opening, situated at the back of its head.
It does not end there. Whereas in other seahorse species the male broods the young in the pouch of its tail, with the pygmy they are reared within its trunk. The female transfers the eggs to the male before they are fertilised. Once this happens it takes about two weeks for the young to be born – and there are often upwards of thirty of them. They are independent from the moment of birth onwards – there is no further parental care. They live away from the reef until they have achieved a certain size and then they head for the hiding place of the gorgonians.
Here you can see a pair of Bargabanti pygmy seahorsess. It is most likely a male and female (they mate for life) with the male "pregnant" and carrying the eggs inside a pouch on its trunk. It was taken under the Lembeh Straits in Indonesia.
Denise's pygmy seahorse (Hippocampus denise) is one of the seven species of true pygmy seahorse. Apart from less distinct tubercles it resembles Bargibant's (the orange variety at least) but it is even smaller. The largest recorded has come in at 1.5 centimeters.
If you want the size contextualised with the presence of a human finger, here you go. Tiny isn’t the word for it, really.
One thing which begs a question is what does a true seahorse eat, whether Denise's, Bargibant or one of the other five? The pygmy seahorse lives off crustaceans even tinier than itself.
Little is known about the conservation status of the seven species – they are all listed as data insufficient by IUCN World Conservation Union which effectively means that not enough is known about their numbers to say what, if any, protection they need. If enough is gleaned about the species then the conservation will have to be done in the wild.
As they are so delicate and small with such a specialized habitat there have been no known successful attempts to keep or breed the species in aquaria. When it has been tried in the past both the seahorses and the gorgonians have perished in captivity. As such, all the photographs in this feature show the pygmy seahorse in its native environment.
In their natural habitats, as you can see, they persist albeit it is thought their population sizes are naturally quite low. One can only hope that their habitats, now fully known at least, can be preserved in pristine condition to ensure the future survival of this remarkable, tiny, species.