Aliens from outer space?

Yesterday we designed different aliens on our data sheet and found out they don't have a spine, some don't have heads, some don't have legs but they all live around the water and some in the water.

Radiation (the sun) replaces water twice a day (the tides). Some aliens go under ground and others have body amour so the can stay up above the mud.  Some aliens stay in one spot and hunt but others move around so they can't get hunted as much.

They really aren't aliens,... the really are creatures of the estuary.  

Angel,Olivia,Jacob,Jake,Macgregor and Tuscan