Sentence:  The tenacity with which <WSD>remoras</WSD> attach to their hosts is best illustrated by the practice of sea turtle fishing by fishermen in the Caribbean and off China and northern Australia [...], and in Yemen and Kenya, where it continues to this day. A fisherman ties a line around the tail of a <WSD>remora</WSD> and throws the fish into the water. The <WSD>remora</WSD> tightly attaches itself to a turtle, and the <WSD>remora</WSD> and its "catch" are then hauled ashore. 
Meaning of the word marked with <WSD> tags:  Any of various elongate fish from the family Echeneidae, the dorsal fin of which is in the form of a suction disc that can take a firm hold against the skin of larger marine animals. (from mid 16th c.)