In 1833, an almost perfectly spherical fish washed ashore in Greenland and was taken to zoologist Johannes Christopher Hagemann Reinhardt in Copenhagen, Denmark. This fish — later known as the footballfish, Himantolophus groenlandicus, or the man-gobbler — was the first anglerfish known to science, wrote Ted Pietsch, a systematist and evolutionary biologist, in his book “ Oceanic Anglerfishes” (University of California Press, 2009). Today, there are about 170 known species in 12 families of deep-sea anglerfish, and a “huge diversity” within those families, Mackenzie Gerringer, ...