The rearward section includes an interior chamber and {TAIL ~ an opening} or channel that extends from the chamber to provide a water flow path between the chamber and {HEAD ~ the surrounding body} of water 
The rearward section includes an interior chamber and { TAIL ~ an opening } or channel that extends from the chamber to provide a water flow path between the chamber and { HEAD ~ the surrounding body } of water
OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH