Concepts
- Surf-dwelling organisms must have special adaptations in order to survive.
- Surf-dwelling adaptations include: thick shells, strong attachments, clustering, flattened or streamlined shapes, and living in protective depressions.
Understandings
The students will be able to 1) identify surf-swept rocky shores and protected shores, 2) describe adaptations of surf-dwelling organisms, 3) name "indicator organisms," and 4) invent an adaptation for a surf-dwelling organisms.
Materials
The following Pacific Coast Information Cards:
Transparency: "Adaptations of Surf-Dwelling Rocky Shore Organisms"
Teacher Information
Waves on surf-swept outer coastlines are important in determining the collections of shore populations. Waves not only exert crushing forces on rocky shore organisms, but also scour rocks and living organisms with sand and shifting sediments such as sand and cobble.
Seaweeds such as the striking Sea Palm can tolerate heavy surf conditions by developing large and rugged holdfasts which anchor them firmly to rock surfaces; by growing in clusters of their own kind; and by developing tough, rubbery stems which whip back and forth with the surf, much like a rubber hose.
Some organisms such as the California Blue Mussel and the Gooseneck Barnacle actually require the high oxygen conditions created by heavy surf. These mussels and barnacles often grow in close association, forming a distinct community of the outer coast shore. Compared to the bay mussel of more protected shores, the California Blue Mussel has much thicker shells and is much larger in size. Its strong byssus threads firmly anchor it to the rocks. Like the Sea Palm, the Gooseneck Barnacle has a long, rubbery stem which whips back and forth with the surf. The mussel and the Gooseneck Barnacle cluster together in depressions, their heavy mass creating further stability against wave action.
