A captive deep-sea creature refused to eat for over five years and survived

A giant isopod known as 'No. 1' at Japan's Toba Aquarium ate its last meal in January 2009, then stopped eating entirely despite staff offering food regularly. It lived for more than five years afterward, going through the motions of poking at food without ever swallowing, before finally dying in 2014 with no clear medical cause found. Giant isopods are scavengers with an extremely slow metabolism, built to survive long stretches of scarcity on the deep seafloor.

— Wikipedia contributors, Giant isopod — Toba Aquarium case, 2009-2014