Compared to shallow-water snailfish, "Pseudoliparis swirei" has several unusual adaptions for its dark and high pressure habitat, including transparent skin that lacks pigment, certain organs and eggs that are enlarged, the muscles are thinner, the ossification of its bones (notably the skull) is incomplete, it appears to have little or no ability to see, there are mechanisms that allow proteins in its body to still function, and differences in the cell membranes for maintaining their flexibility. "Pseudoliparis swirei" is named for Herbert Swire, the First Navigating Sub-Lieutenant of and author of 'The Voyage of the "Challenger", a personal narrative of the historic circumnavigation of the globe in the years 1872-1876'. In 1876 the expedition found the Challenger Deep, habitat of the Mariana snailfish. A study of mature females showed that mature eggs of this fish species are unusually large, up to in diameter. In total, there were up to 23 mature eggs for each female (each larger than in diameter), which were alternated with immature, small eggs, the number of which was about 850. Eggs of intermediate size were rarely seen. Even in the largest eggs, no structures were found that indicate the development of the embryo within the eggs. There are indications that the larvae of "P. swirei" and at least some other hadal fish spend time in the open water at relatively shallow depths, less than .