Dorsal fin: Keeping fish upright plays a key role in fish balance. If you lose it, you will lose your balance and turn over.
Pectoral fin and ventral fin: Balance. If you lose balance, the fish will swing from side to side.
Tail fin: determines the direction of movement. If you lose it, the fish won't turn.
Gluteal fin: coordinate other fins and play a balance role. If you lose it, your body will shake slightly.
pectoral fin
Pectoral fin: when the caudal fin is not moving, the pectoral fin opens to both sides of the fish, and when it swings back and forth, the fish moves forward; When a pectoral fin swings, the fish turns to the immobile side; If it loses its balance, the fish will swing from side to side, equivalent to the forelimbs of higher vertebrates, behind the left and right branchial holes. The main function is to make the body move forward and control the direction or "brake" function during the movement.
ventral fin
Abdominal fin: equivalent to the hind limbs of terrestrial animals, it can help dorsal fin and gluteal fin to maintain the balance of fish and help fish lift and turn. The position of ventral fins varies from fish to fish, and the ventral fins of cartilaginous fish are generally located on both sides of cloacal foramen. Similar in shape to pectoral fin, but slightly smaller. The ventral position of the pelvic fin of teleost is called the ventral position of the pelvic fin. This is a relatively primitive species, such as carp, salmon, catfish, herring and so on; The chest located in front of pectoral fin and behind gill cover is called ventral fin chest position, such as perch, yellow croaker and snapper; The throat between the two gill covers is called ventral fin throat position, such as catfish and? Family fish. The chest position and throat position of ventral fin are advanced features of fish after evolution. These ventral fins with different positions are important symbols in the evolutionary history of fish and are of great significance in animal taxonomy.
dorsal fin
Dorsal fin: an intermediate fin that grows along the midline of the back of aquatic vertebrates and is supported by fins that grow on the back. Mainly plays the role of balancing fish. But there are also some long fish, dorsal fins and anal fins that can help the body move and push the body forward quickly. For example, the dorsal fin of hairtail, the anal fin of electric eel, and the dorsal fin and anal fin of sea eel can all push the body forward. Another example is the special shape of the hippocampus, which also relies on the tiny dorsal fin movement to push the body forward.
anal fin
Gluteal fin: The gluteal fin is located in the midline of the fish's abdomen and behind the anus, and its shape and function are similar to those of the dorsal fin. Its basic function is to maintain the balance of the body, prevent tilting and swaying, and coordinate swimming. Most fish have 1 anal fin, while cod has 2. Some are all fins, some are fins and spines. The anal fin of blind eel can be connected with caudal fin and dorsal fin, and the base of anal fin of sea eel and flounder is very long.
tail fin
Tail fin: One of the intermediate fins of fish and other vertebrates, located at the tail. What is seen in cirrhosis is primitive, the spine is straight to the end, and the caudal fin is separated by it, becoming a primitive conformal tail, with dorsal and ventral symmetry. In cartilaginous fish, the end of the spine bends to the back. Correspondingly, the dorsal lobe of caudal fin is developed, and the ventral lobe is small, showing an asymmetric curved tail shape. When it comes to teleost, the dorsal lobe becomes smaller, the ventral lobe becomes larger, and the appearance becomes a concentric tail again. The nearly primitive orthomorphic secondary tail seen in eel and lungfish is called gephyrocercal. All kinds of tails go through the stage of primitive symmetry when they occur. The whale's caudal fin consists only of horizontal skin folds.