Scientists inspected some fish living in the sea and found that they were different in shape, size, and species, but they had a special structure on the gill sheet that could exclude salt. The scientists called it a "chloride-secreting cell" tissue. Scientists also examined some freshwater fish and found that although freshwater fish are also different in size, size, and species, there is no such "chloride-secreting cell" tissue on the gill sheet. Therefore, scientists believe that these Species is the reason why marine fish live in the sea for a long time, but the meat does not have a salty taste. From the above information, we can learn:. ['There is a special structure on the gills of sea fish that can eliminate salt.', 'The higher the saltiness of the seawater, the more developed the "chloride-secreting cells" of the marine fish.', '"Chloride-secreting cells" tissue is unique to marine fish.', 'Marine fish and freshwater fish are completely different in size, size and species.']