Of all the sharks that biologists don’t know a lot about, Greenland sharks (Somniosus microcephalus) stand out as particularly mysterious. Sleeper sharks, a family that includes Greenland sharks and 19 other species, are slow-moving scavengers that inhabit arctic and subarctic waters. So it came as a great surprise to Devanshi Kasana, a graduate student at Florida International University, to reel one in as she was tagging tiger sharks off the coast of Belize in May of this year. A report of the encounter, the first time that a sleeper shark has ever been found in the western Caribbean, was published this month in Marine Biology.
Kasana and her coauthors write that the shark was either S. microcephalus or a hybrid between that species and the related Pacific sleeper shark (S. pacificus). While it certainly wasn’t the type of shark expected to be caught in the Caribbean, scientists know so little about sleeper sharks that they can’t say for certain that these fish don’t frequent those waters, perhaps staying close to the seafloor where temperatures are chillier.