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30 March 2020
By Danel Wentzel
Meet Hippocampus nalu, the Indian ocean's first pygmy seahorse. Discovered in 2017 by Savannah Nalu Olivier, a local dive instructor, this rare seahorse has now officially been recognised as a new species after being included in Zookeys (an international scientific journal) this month by Short et al., 2020.
The species of pygmy seahorse was described from two collected specimens off a known flat, sandy reef at around a depth of 14-17m in Sodwana bay, South Africa. Their discovery has been described as "finding a kangaroo in Norway" by Richard Smith, a marine biologist and pygmy seahorse expert.
In the South African languages, Xhosa and Zulu, the word "nalu" means 'here it is' which was a fitting name for the little seahorse considering it was there all along, waiting, until its discovery. "Nalu" is also the Hawaiian word which refers to the waves or surf of the moana (ocean), making the name even more fitting since H. nalu was first observed moving about in strong surge along it's sandy habitat.
Spending some time in Sodwana Bay I would lie if I said I haven't spent endless hours searching for these elusive seahorses that, before its official discovery, were mere rumours among the local dive instructors. I am pretty sure we have narrowed down their location to a small patch on 2 mile reef, where Open Water and Advanced students visit on a daily basis to perform skills such as navigation and search and recovery. But for now we can leave them unbothered in their hideaway.
You can read up more about H. nalu and their discovery on Business Insider South Africa.
More about Seahorses
Seahorses are part of the family Syngnathidae which contains 300 species within 57 genera (Hamilton et al., 2017). Members of this family include the seahorses, pipefishes, pipehorses and seadragons. They are all uniquely characterised by their fused jaw which makes feeding possible, male brooding as well as their cryptic shapes and behaviours.
All seahorses fall under the genus Hippocampus which comprises of 46 known species. Hippocampus is derived from the Ancient Greek word hippokampos - hippos meaning "horse" and kampos meaning "sea monster" (Foster and Vincent, 2004).
They can be find in a wide range of habitats in temperate and tropical regions, which include sediment habitats, seagrass beds, estuaries, rocky reefs, coral reefs and mangrove forests. Generally pygmy seahorses are found in calm, sheltered waters (like the Southeast Asian pygmy seahorse which is found in sheltered coral reefs). This makes the discovery of H. nalu even more astonishing as it was found on a reef exposed to powerful swells.
Male seahorses have a "pouch" where females deposit up to 1500 eggs. The male then carries these eggs for 9-45 days until they hatch, giving "birth" to tiny little seahorses which get released into the water.
References
Hamilton H., Saarman N., Short G., Sellas A.B., Moore B., Hoang T., Grace C.L., Gomon M., Crow K., Simison W.B. (2017) Molecular phylogeny and patterns of diversification in Syngnathid fishes. Molecular phylogenetics and Evolution 107: 388–403.
Foster S.J., Vincent C.J. (2004). "Life history and ecology of seahorses: implications for conservation and management". Journal of Fish Biology. 65: 1–61.
Short G., Claassens L., Smith R., De Brauwer M., Hamilton H., Stat M., Harasti D. (2020) Hippocampus nalu, a new species of pygmy seahorse from South Africa, and the first record of a pygmy seahorse from the Indian Ocean (Teleostei, Syngnathidae). ZooKeys 934: 141-156.
Lockhart, H., 2016. Everything You Ever Wanted To Know About Seahorse. [online] Two Oceans Aquarium. Available at: <https://www.aquarium.co.za/blog/entry/everything-you-ever-wanted-to-know-about-seahorses> [Accessed 30 March 2020].
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