On the seat was a cockatiel in a cage, and safely confined in the car being towed behind the truck was a cat. The cat, the cockatiel, and nearly all the baby zebrafish survived the trip. Zebrafish crossing the Mississippi. My particular point of attack is to study how a muscle cell decides to become slow muscle fiber or fast muscle fiber. Muscle cells are extremely abundant and accessible.
Slow muscle is for locomotion, steady, constant movement.
In fish, there's the same dichotomy. Swimming through the aquarium or the ocean, steady cruising, requires slow muscle fibers. Trying to get away from the fish net or the shark requires fast muscle fibers. The familiar salmon steak is composed mostly of fast muscle fibers, pinkish orange in most salmon. At each outer edge, just under the skin, is a crescent of slow muscle which is darker.