Molluscs sleep

like fishes, and crustaceans also. It is plain also
that insects sleep; for there can be no mistaking their condition of
motionless repose. In the bee the fact of its being asleep is very
obvious; for at night-time bees are at rest and cease to hum. But
the fact that insects sleep may be very well seen in the case of
common every-day creatures; for not only do they rest at night-time
from dimness of vision (and, by the way, all hard-eyed creatures see
but indistinctly), but even if a lighted candle be presented they
continue sleeping quite as soundly.