People throw litter on the beach and even into the sea.The litter has become the "home" of hermit crabs（寄居蟹）.Believe it or not，it is happening all over the world.Scientists have seen hermit crabs using bottles，bulbs（灯泡）and even broken glass.
Unlike other crabs，hermit crabs are born with soft bodies，so they need to look for shells（先）.They first look at the shells' type，size，and color.Then，they use their legs to check the inside of the shells to make sure they are the right size.As they grow，they give up their old shells and find bigger ones to live in.
However，"litter shells"can bring danger to hermit crabs.Different from natural shells，plastic waste（塑料垃圾） is often brighter in color.Other sea animals can find hermit crabs more easily.The crabs could also get hurt or die when they go into plastic bottles.Why do they choose a"litter shell"？Hermit crabs find shells by a smell.Sea plastic smell is similar to the smell of natural shells.
Now，man﹣made"shells""might be interesting to hermit crabs.Plastic waste is lighter than natural shells.The hermit crabs can go around easily in them.
