No pectoral or pelvic fins, only one dorsal, caudal and anal fin.
No scales, the body is covered with a protective mucus.
This moray eel is solitary, but it often stays with cleaning shrimp with which it shares its meals and offers protection in exchange for deworming.
Some sharks can stay motionless on the sand (white tips reef sharks, nurse sharks, etc.).
These sharks don't have to swim to bring oxygen to their gills like other sharks (grey, hammerheads tc.)
Mammals have a horizontal tail.
Fishes have a vertical fin.
The tiger shark has slender marks similars to the lines of tigers, hence its name.
When it is juvenile, these marks are round and not vertical. They change when it grows.