Consider
- Dupligroups
The thorn has its parent as indicated by outliner windows and properties window. The duplication mesh has duplication indicated by Duplication Panel. Faces and Scale. Your mesh is the Shark. The mesh in picture happens to be a stem or tentacle. The Scale selection uniformly scales the thorn to the size of the face which may be of interest to you.
- Particle Systems
Displacement Modifier
You may also see Tapering a tentacle mesh with uniformly scaled suction discs