Knysna seahorse facts for kids
The Knysna seahorse or Cape seahorse (Hippocampus capensis) is a special type of fish in the Syngnathidae family, which includes other seahorses. It is found only in a few places along the south coast of South Africa. These places are brackish water areas, meaning the water is a mix of fresh and salty water. You can find them in the Keurbooms River estuary near Plettenberg Bay, the Knysna Lagoon, and the Swartvlei system near Sedgefield. Because they live in such a small area, these seahorses are in danger of disappearing.
Quick facts for kids Knysna seahorse |
|
|---|---|
 |
|
| Conservation status | |
| Scientific classification |
Contents
What Does the Knysna Seahorse Look Like?
The Knysna seahorse is a small and delicate animal. It can grow up to about 12 centimetres long, which is roughly the length of a pen. Its colour can change a lot depending on where it is and how it feels. It might be pale green, brown with dark spots, or even purplish-black.
Its body is covered in a series of bony rings, like armour. It has a short snout and a smooth, curved neck without a crown-like bump on its head. The tail is strong and can be used to hold onto things, like plants, or to grasp another seahorse during mating.
Where Do Knysna Seahorses Live?
Knysna seahorses mostly live in areas with lots of plants underwater. They like places where at least 75% of the area is covered in plants. They are often found near five main types of aquatic plants: Zostera capensis, Caulerpa filiformis, Codium extricatum, Halophila ovalis, and Ruppia cirrhosa.
The Keurbooms and Swartvlei estuaries have many dense plant beds. However, in the much larger Knysna Lagoon, only about 11% of the area has enough plants for the seahorses. This means large parts of the Knysna Lagoon might not be suitable homes for them.
These seahorses are very good at living in estuaries. They can handle a wide range of water conditions, including different salt levels. They can live in water that is almost fresh or very salty.
Reproduction and Life Cycle
Knysna seahorses usually breed during the South African summer. This is when the water temperature gets close to 20 degrees Celsius. They become old enough to have babies when they are about one year old and around 6.5 centimetres long.
Like all seahorses, the male carries the eggs in a special pouch until they hatch.
How Many Knysna Seahorses Are There?
Scientists have counted the Knysna seahorse populations. In 2002 and 2003, they found that the numbers in the Keurbooms and Swartvlei estuaries could sometimes be much higher than in the larger Knysna Lagoon. However, these numbers can change a lot.
For example, a period of strong river flow in the Keurbooms estuary might have caused the seahorses to disappear there for a while. This suggests that the Keurbooms estuary might not always have seahorses, but only when conditions are good. More recent surveys found the seahorses again, but floods in 2007 and 2011 caused their numbers to drop.
Scientists have studied the seahorses' DNA. They found that even though the seahorses in each of the three estuaries have slightly different DNA patterns, they are all the same species. This means that if needed, seahorses could be moved from one estuary to another to help their populations.
Evolution of the Knysna Seahorse
The Knysna seahorse is closely related to a widespread seahorse called H. kuda, which lives in the Indian Ocean. The Knysna seahorse is smaller, has a shorter snout, and a smaller "coronet" (the crown-like part on its head). These differences likely help it move better through the thick seagrass beds found in South African estuaries.
Protecting the Knysna Seahorse
Because the Knysna seahorse is endangered, efforts are being made to protect it. Some Knysna seahorses are kept and bred in aquariums. For example, the Two Oceans Aquarium in Cape Town and the Antwerp Zoo have populations of these seahorses. They are also sometimes bred and sold for people to keep as pets in aquariums, which is part of the ornamental fish industry.
