Animal WorldFish, Amphibians, and Reptiles |
What general characteristics do all fishes have in common? |
All fishes have the following characteristics: 1) gills that extract oxygen from water; 2) an internal skeleton with a skin that surrounds the dorsal nerve cord; 3) single-loop blood circulation in which the blood is pumped from the heart to the gills and then to the rest of the body before returning to the heart; 4) nutritional deficiencies, particularly some amino acids that must be consumed and cannot be synthesized.