On the beach above the docks - there is a red crab that will jump out once in a while. Once you see it, grab a kid & place it to "distract" the crab. Grab another kid. While their distracting the crab, grab an adult to catch it.
I was able to have 2 adults catch them in one round.
The crabs will add a lot of food after the rocks are cleared, to the food amount, too. Very worth while using if food is still low.