a relax or happy shark:
-body held straight, loose
-pectoral fins out to the sides
-lazy, slow body movements & very limited sweep of tail
-chills out at a higher elevation
a nervous or agitated shark:
-pectoral fins dropped low, pointing down for fast movement
-arched back (DANGER! Like mammals baring their teeth)
-wide sweeps of the tail, rapid zig-zagging body movement
-diving LOW, especially pressing the body against the sea floor