The enormous stomach of this anglerfish shows it ate well before it died. And now, after 13 years, scientists have identified its last meal, using micro-CT scanning.
The rare Hairy anglerfish (Caulophryne pelagicahas) been part of a collection at the Natural History Museum since it was captured on a research cruise near the Cape Verde Islands in the East Atlantic in 1999. The fish is now preserved in a jar of alcohol, and is one of only 17 examples discovered so far.
Its hugely distended stomach has perplexed researchers — they wanted to know what was inside it, but the rarity of the specimen meant they were reluctant to cut it open in order to find out.
Anglerfish live at depths of 2,500m, where they lie in wait for prey. At these sorts of depths food can be scarce, so they are capable of swallowing huge prey.
Museum fish expert James Maclaine said he could tell the anglerfish’s meal was a large bony fish by feeling the stomach, but without looking inside he couldn’t tell exactly what kind.
A CT scanner uses thousands of X-rays to create a detailed 3D image. Using this process the skeleton of the prey fish was revealed, sitting inside the anglerfish's stomach. Its backbone, eye socket and otoliths were clearly visible.
Because otoliths are distinct to different fish species, Maclaine could then identify the anglerfish's last meal as a long, slender deep-sea fish called Rouleina atria, around twice its own length.
There's a particularly good video on the Natural History Museum's website, where you can see the process, along with the 3D X-rays showing the prey inside the anglerfish.
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