Striking image lets you see inside a deep-sea anglerfish's killer jaws

With its gaping jaws and pointy teeth, this humpback anglerfish (Melanocetus johnsonii) seems even more terrifying when its inner intricacies are revealed. The deep-sea monster, also known as Johnson’s abyssal seadevil, was photographed by Solvin Zankl.

The image shows the fish after a long process of cleaning and staining to reveal its internal structures. Scientists used a digestive enzyme to remove the soft tissue, exposing bones and collagen, which were then stained. Blue shows cartilage, while the red is bone. Sometimes not all tissues become transparent during the chemical processes: for example, the dark mass (left) is the fish’s stomach.

This technique offers a rare glimpse inside the anglerfish, from its gills to its two sets of impressively scary jaws – just one of the remarkable adaptations that have evolved in deep-sea species, says Zankl. But don’t worry: females, like the one shown here, grow to about 153 millimetres long, while males are a mere 28 millimetres.

The fish live at a depth of about 900 metres in tropical oceans. This specimen was collected from the Benguela Upwelling System, very fertile deep waters in the South Atlantic Ocean, off the coast of South Africa and Namibia, during a research expedition to document the region’s wildlife.

Since deep-sea photography is a big challenge, Zankl says that working with scientists lets him visit otherwise inaccessible places. Documenting such creatures sheds light on their biology and on the broader ecological processes in fragile ecosystems, he says.