Turtle eat jellyfish because they are omnivore, which means they eat both plants and animals. In the wild it easy for turtles to catch jellyfish because they move very slowly in the water. That is why, if a hungry turtle comes across a jellyfish, it won’t hesistate to swim up to it and eat it.
sea turtles can see in the dark. They don't have night vision to see clearly in the dark, but once their eyes adjust in the dark, they see things more in red coloured shadows because they have Tapetum lucidum in their eyes which is known as the redness gene.