2 Read the text and circle the correct linking word. Do fish sleep? If you really want to know the answer to the question, the answer is: sort off Fish do sleep, (1) because/but they don't sleep as we know it. They don't have eyelids (2) that is why/when they can't close their eyes like people or animals do. Some fish just lie on the bottom of the sea at night, and not all of them swim around all the time; they just rest. (3) Firstly/That is why, in the dark, many fish have a lower rate of metabolism, (4) but/so their body slows down and that is much like sleep. This has the same effect as a night's sleep has on humans. (5) Although/ e) So, the answer is (6) that/what fish enter a sleep like state.