ALT An Argyropelecus olfersii on a black background. Credit: Emma Curtis.
ALT Counter-illumination from an Argyropelecus olfersii hatchetfish, photographed in darkness. The pic is quite blurry but the light is bright sky blue. There are parallel rows of round light organs, and an arc of light organs on the underside of the chin. Credit: own photo.
ALT A bunch of mesopelagic fish in an orange plastic basket. There's quite a diversity but the most common and obvious component of the catch are the bright silver hatchetfishes. Credit: own photo.
ALT Smal (max length of 7,5cm), short lived (2 ), small fecundity and planktonivorous fish.
ALT An assortment of mesopelagic fishes, photographed on a white plastic conveyor belt. On the left there are some squids and a large red jellyfish. In the centre top there are several A. olfersii, with lots of smaller A. hemigymnus below. Some lanternfish, pearlsides, and barracudinas are also below the hatchetfish, alongside a large Cubiceps. On the right there are a bunch of viperfish and two small sabertooths, then above that some pencil smelts. Credit: own photo.
ALT An Argyropelecus (actually A. aculeatus) specimen laying flat in a hand, illuminated by angled sunlight. The photophores cover the entire lower surface of the fish, and are a pale amethyst colour. They are roughly oval in shape. Credit: own photo.
ALT An Argyropelecus olfersii hatchetfish held between fingers, photographed from above. The skin on the dorsal surface is very dark, and the mouth is agape, slightly shocked. The eyes are large and slightly bulging, with beautiful metallic blue irises. Credit: own photo.
ALT An Argyropelecus olfersii hatchetfish photographed against a white plastic measuring board. The fish is about 10cm in length, including the translucent tail fin. The fish has a very deep body, covered in silver skin, which ends in a nearly triangular trunk section. The mouth is huge and angled nearly vertically. The top of the fish is dark, the underside is covered in oval-shaped light organs. The eyes are blue and point vertically. Credit: own photo.
ALT Two quite damaged specimens of Opisthoproctus soleatus in a small jar. The left specimen has damaged skin on the underside, showing a pearlescent/silvery layer of tissue that is highly reflective. Credit: own photo.
ALT A figure showing two illustrations of Opisthoproctus' anatomy. The upper illustration is of the underside, or "sole" - the whole fish is covered in a layer of large, grey scales. The second illustration shows the internal anatomy of the anus region of the fish - there is a large black organ with white reticulations which hosts the bacteria. Credit:Poulsen, J.Y., Sado, T., Hahn, C., Byrkjedal, I., Moku, M. and Miya, M., 2016. Preservation obscures pelagic deep-sea fish diversity: Doubling the number of sole-bearing opisthoproctids and resurrection of the genus Monacoa (Opisthoproctidae, Argentiniformes). PLoS One, 11(8), p.e0159762.
ALT A front-facing view of Opisthoproctus in its jar. The eyes are huge and cylindrical, and the mouth is small, making a sort of :^o face. Credit: own photo.
ALT Dorsal view of a preserved Opisthoproctus specimen. The eyes are HUGE, and pointing directly towards the camera. The head fits about three times into the length of the body, and about half of that head is filled with the eyes. The mouth is a pronounced, rather smug little snoot, with large nostrils. The caudal fin is bent a little. There is still some dark skin on the back. Credit: Own photo/NHM Specimen.
ALT A fresh barreleye specimen phtoographed on a scratched metal specimen. The fish has a very odd shape, with a flat underside and a very stocky body, with a wide tail fin. The skin is damaged, with almost all the scales gone, with only black scale pockets remaining. The head is very tall and large, and is bizarre, with two huge upwards-facing barrel-shaped eyes and a tiny mouth near the end of the chin. The skin on the head is bizarrely beautiful, with iridescent blue-green colours, like the rock Labradorite. Credit: Jessica Chen/NOAA.
