so they can see , spastic.
The eyespot allows algae to move to areas where the light is brighter
It has light and it also produces its own light and thus when it is very dark it could lit up its own light and see clearly.
behavioral
john( the fish produces light ), Mary ( the fish produces light ), ,Toby ( the fish produces light ), may ( the fish produces light ),
Light , which is useful Heat , which is NOT useful.
Fish live in it
it's useful for light and safety.
Both are acceptable, depending on context. For example:Fishing bait is useful to fisherman.Fishing bait is useful for catching fish.
The light bulb is useful because it lights up places!
both
Of course it is in its name.
light fish live in the artic ocean