Sense Organs

Although they have been considered primitive vertebrates, their olfactory and visual senses have been well developed.

http://www.arkive.org/sea-lamprey/petromyzon-marinus/image-A20966.html

 

Sea lamprey’s also have a lateral line that allows them to sense movements in the water.

http://crescentok.com/staff/jaskew/isr/botzo/zclass8.htm