Fascinating fish: Sturgeon in Hellabrunn Zoo
The newly created pond situated between the Jungle House and the aquarium is now home to several species of sturgeon. Known as a source of caviar, the impressive prehistoric fish have existed for over 200 million years.
"Mum, look, sharks!" is a cry often heard from children. However, often the fish the little fingers point at are not actually fearsome creatures, but harmless sturgeon. Sturgeons do share some similarities with sharks: they are both cartilaginous fish, i.e. they have no bones, only cartilage; sturgeons can glide through water just as majestically as many shark species and both have asymmetric tail fins. There are currently 16 sturgeons living in the 375,000 litre pond at Hellabrunn Zoo: White, Russian and Siberian sturgeon as well as stellate sturgeon.
"Sturgeons are sometimes called ‘living fossils’ as they have existed for more than 200 million years," says zoo director Rasem Baban. "Their complex biology also makes them particularly interesting fish. Sturgeons have 120 to 240 chromosomes, depending on the species. Humans, on the other hand, only have 46. At Hellabrunn, we have four endangered sturgeon species living at the zoo."
The 16 sturgeons living at Hellabrunn are between eight to ten years old. Of the 74 existing sturgeon species, the most famous is the Beluga known for its caviar. Beluga sturgeon can live up to 100 years and weigh up to a tonne. Most sturgeons live in estuarine or marine waters and only migrate to freshwater to spawn. However, the sturgeons at Hellabrunn are still too young to reproduce.
Sturgeons - apart from the Beluga sturgeon - have their mouth located on the underside of their lower jaw. They have no teeth. Instead they have four whisker-like barbels in front of the mouth which house taste buds that allow them to smell, locate and taste the food on the seabed or riverbed. Their diet consists primarily of worms, molluscs, crustaceans, insect larvae, mussels and small fish, which are sucked into their wedge-shaped snout and crushed into smaller pieces. Sturgeons do not have scales. Instead they have rows of bony, shell-shaped plates called scutes to protect the skin.
Almost all sturgeon species are classified as either endangered or critically endangered. Their highly prized meat and eggs (more commonly known as caviar) have led to massive overfishing and a decline in sturgeon populations. River development and pollution have also contributed to the decline in stocks. The European sea sturgeon, once endemic in Germany, became extinct about 100 years ago. The species is now expected to make a return to German rivers with the help of reintroduction projects.