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www.thevillagenews.co.za
10 June 2020
MY ENVIRONMENT
Sensational new SA seahorse discovered By Anina Lee
R
ecently I have written about amazing tiny animals that delight us when we see them close up through macro-photography. There were brilliantly patterned nudibranchs (sea slugs) and the tiny dancing peacock spiders. Now we have another – this time a tiny fish. Just recently a brand-new species of pygmy seahorse was discovered in Sodwana Bay on the north-eastern coast of South Africa. What was so remarkable about this discovery is that pygmy seahorses were thought to be confined to Indonesian waters, living on coral reefs. They had never before been found in the Indian Ocean, and certainly not 3 000 km away in South Africa. But before I describe this remarkable little critter, let’s look at seahorses in general. Seahorses (Hippocampus species) are fish that can be recognised by their horse-like head that is right angled to the body and a muscular tail that they use as an anchor. Sea horses are well camouflaged and
are generally found holding onto sea grass stems, coral heads or artificial reefs where they sit and ambush their prey. An unusual feature of the seahorse is that it has a very rudimentary stomach and therefore has to graze constantly because food moves through their digestive system quickly. They need to eat up to 3 000 small copepods (tiny crustaceans) a day to satisfy their energy requirements. Like most fish they have gills, a swim bladder and fins. Their eyes can move independently of each other, and they can change colour, rather like a chameleon. Knysna Seahorse (Hippocampus capensis) The Knysna seahorse is endemic to South Africa and is the only seahorse species known to exclusively inhabit estuaries. It is perhaps well known for the wrong reason – it is highly endangered. Knysna seahorses have the dubious distinction of being the first seahorse species to be classified as endangered by the International Union for the Conservation of Nature (IUCN). The Knysna seahorse is a medium-sized seahorse (8 – 12cm) with a characteristic short snout and the males have a slight keel above their brood pouch. They are typically mottled brown, but can range in colour from white, yellow, orange, green and beige to brown and black.
A unique and unusual characteristic of seahorses is that the males carry the babies in a true pregnancy, with up to 200 babies hatching after a gestation period of 14 – 45 days. PHOTO: Reddit
Knysna seahorses have the smallest geographical range of any seahorse and can be found in only three estuaries – Knysna, Swartvlei and Keurbooms. Before 2002 they could also be found in the Klein Brak Estuary. Like most seahorses they are monogamous. A unique and unusual characteristic of seahorses is that the males carry the babies in a true pregnancy, with both internal fertilisation and the pouch tissues having capillaries that supply the embryos with oxygen and nutrients. The female lays her eggs straight into the brood pouch of the male, where he fertilises them. Up to 200 babies can hatch after a gestation period of 14 – 45 days (depending on the water temperature). The babies are tiny, measuring only 0.8 – 1.6cm in length, but they have to fend for themselves in the big world. All over the world seahorse populations are threatened by degradation of their habitat. They are also accidently captured in fishing gear, and overexploited for use in traditional medicines and the aquarium trade. Pygmy seahorses Pygmy seahorses are a group of miniature syngnathids (technical name for seahorses and pipefish) – fish that live mainly in the Coral Triangle region of south-east Asia. They range in length from 1.4 – 2.7 cm between the tip of the tail to the end of the snout – that’s about the size of your thumb nail.
that a pygmy had never been recorded from the Indian Ocean before. He described it as the equivalent of finding a kangaroo in Norway! He immediately began planning a trip and a few months later, he and Louw were in Sodwana Bay and ready to go hunting. They joined up with Savannah, who had been watching these tiny fish for some time and was vital in the process. They managed to find several of the
small fishes, hidden amongst tiny algal fronds. They found a breeding pair of adults and even managed to find a tiny baby, just one centimetre long! Dr Smith and colleagues from around the world named this new species as the Sodwana Pygmy Seahorse or South African Pygmy Seahorse – Hippocampus nalu. The name is in recognition of Savannah Olivier, who first brought this amazing fish to the world’s attention.
RIGHT: Bargibant’s pygmy seahorse (Hippocampus bargibanti) blends in with the coral on which it lives. BELOW: The highly-endangered Knysna seahorse (Hippocampus capensis) is endemic to South Africa and is the only seahorse species known to exclusively inhabit estuaries. BOTTOM: The new species of pygmy seahorse (Hippocampus nalu) that was recently discovered in Sodwana Bay.
PHOTO: Richard Smith, Ocean Realm Images
PHOTO: Wikipedia
South African pygmy seahorse (Hippocampus nalu) In April 2020 Dr Richard Smith described the events that led to the discovery of the South African pygmy seahorse. In 2018 he and a South African seahorse specialist, Dr Louw Claassens, from the IUCN Seahorse, Pipefish and Seadragon Specialist Group, visited Sodwana Bay in search of a possible new species. A local diver, Savannah Nalu Olivier, had found the tiny creature which she did not recognise, but took a photograph and showed it to Dr Claassens, who in turn contacted Dr Smith. He immediately recognised the image as a pygmy seahorse, but knew
PHOTO: Richard Smith, Ocean Realm Images
