What's new at Basel Zoo

15 baby black-tailed antenna rays are currently being reared behind the scenes at Basel Zoo. Basel Zoo is the only zoo in the world that is home to this species, and in 2016 successfully bred the first baby black-tailed antenna rays ever to be born in captivity.

Nine of the 15 baby rays were born on 27 June, and the other six were born on 7 October. The mother of those born in October is only two years old and is a first-time parent. As is common among young rays with children, her litter is smaller than the other mother’s because she is significantly smaller herself. The pups are doing well and are already eating all of the mosquito larvae, chopped mussels and prawns offered to them.

Pups hatch in their mothers' bellies

The pups in the second litter are noticeably darker in colour. This may be because the litters have different fathers: the father of the younger litter is also somewhat darker than that of the older, lighter-coloured pups. Among the four litters born at Basel Zoo and the few litters born to private breeders, the record number of pups in a single litter is 16 pups. The pups develop in eggs within their mother’s body. The transparent egg shell breaks during birth and the mother gives birth to live young. This type of reproduction is called ovoviviparous reproduction.

The sensitive young animals are still being kept behind the scenes at Basel Zoo and will be moved into other aquariums when they are about six months old. Visitors can see the (darker-coloured) father of the new litter in aquarium number 26. Basel Zoo is the only zoo worldwide to have black-tailed antenna rays.

Scientifically described for the first time eight years ago

Black-tailed antenna rays were scientifically described for the first time in 2011, and very little is known about their biology. Just like the other around 40 species of freshwater stingrays, this species has a venomous sting on the top of its tail. They live in the upper Amazon river in Peru and in its tributaries, from the Pachitea River to the Itaya River, which runs alongside the city of Iquitos. Unlike most freshwater stingrays, black-tailed antenna stingrays do not bury themselves in the sand at the bottom of the riverbed. They have very small eyes that do not protrude very far.

More than 600 species of ray live in the Earth’s oceans and they are the closest relatives to sharks. Their body is plate or disc shaped, very different to the normal shape of a fish.