The scientists studied different tidal flats in Japan to see how many different kinds of small sea creatures lived there, how much they weighed, and how diverse the populations were. They found that the areas with more species also had more total weight of creatures. Some tidal flats had more endangered species, even if they didn't have the highest number of species or weight. The study suggests that looking at multiple factors is important to understand the communities of creatures living in tidal flats.