The fish that lives in a jellyfish

The underwater photographer Tim Samuel – last December – during a dive in the waters of Byron Bay (Australia) came across a jellyfish with a fish still alive and healthy inside. “The fish was trapped, but controlled the movement of the jellyfish,” explains the photographer. In practice, the guest swam, but the jellyfish also moved: the result is that, sometimes, the duo found themselves circling.

But who are the protagonists of this bizarre situation? According to Ian Tibbetts, marine biologist from the Center of Marine Science of the University of Queensland, the jelly creature could be a cubomedusa (lethal to humans), and the fish a young giant indopacific carango (Caranx ignobilis), known to seek shelter from predators under the tentacles of jellyfish. The baby, in fact, may have come too close to seek protection, ending up incorporated in the other animal.

Stefano Piraino, marine biologist at the University of Salento, has a different opinion, according to whom it is less and less unusual to see fish that eat jellyfish. “In this case – he explains – the little fish entered the jellyfish to try to eat the handlebars or the radial channels, that is the points where the gonads can form, which are the most caloric parts. Although without a handlebar, the medusina is certainly capable of long life, and of regenerating the handlebar. The fish was greedy: it stuck with its head and remained inside the jellyfish, after tasting what would have seemed to him the most succulent bite ยป.