This activity is a great way to see the inherent differences between ecosystems and food webs that come from the same "stereotype," which in this case both ecosystems are found in water!
This document contains 2 separate food web abilities: freshwater and marine. In 2 sets, there are pictures of multiple producer/ consumers, predator/ prey relationships. Allow students to first sort them into specific piles based on whether they are producers or consumers or where they would fall on the Rule of 10 pyramid. Then, give them time to use the pictures to create a complex food web with one of the sets.
Included in the card sets are titled pictures and descriptions of the organisms.