Marine Biology

Sub-tidal Zone

Below the lower intertidal zone is the underwater sub-tidal zone. The rocky coast sub-tidal zone has an abundance of life. Sea urchins eat giant kelp, the biggest seaweed in the ocean, by feeding on its holdfasts. Sea stars cling to the rocks. The movement of the sea stars is dictated by the tides. When the tide comes in, the sea stars move from the sub-tidal zone to the intertidal zone to feed on the mussels. There is also a variety of sea anemones, as well as crabs and lobsters, hiding in the rock crevices. Lobsters come out of their hiding places at night to feed. Predatory fishes that come from the open ocean, prey on the abundant invertebrates.