The Purple Sea Urchin, unlike the Red Urchin or the Green Urchin, favors rough water and creates its own unique microhabitat in stone by gradually wearing down the rock over the years to create a hollow in which it can safely weather even the most pounding surf. Only the abrasive action of the long, sharp spines forms the hollow. So effective is this mode of protection that one is convinced that the urchin had sealed itself into a self-created prison for life. Food for the imprisoned urchin appears to be mostly drift seaweeds, captured by the tube feet.
Chitons, limpets, and abalone are specially adapted to survive the pounding surf by their low, flattened bodies and streamlined shapes. These organisms also have large, fleshy, muscular feet, which create a powerful suction to anchor them to the rocks.
The wide-ranging Purple or Ochre Star remarkably clings to wave-swept rocky shores just below the mussel beds. This tenacious sea star sports a tough, slimy body and is quite capable of creating a surprisingly powerful grip with its hundreds of sucking tube feet.
- Show the students a picture of a surf-swept rocky shore. Ask the students whether this would be a safe place to explore tidal pools. Why would this not be a safe place to explore? (Unpredictably high waves, powerful waves, shifting boulders, shifting logs, being swept out to sea.) Brainstorm signs of a surf-swept rocky shore. Tell the students that today they're going to learn how to identify a surf-swept shore and that this knowledge might someday save someone's life.
- Brainstorm problems of survival for surf-dwelling organisms on a rocky shore. (High waves, strong powerful waves, shifting boulders, abrasive sand and gravel, shifting logs, being swept out to sea.) Emphasize that surf-dwelling organism must survive man of the problems that could easily kill people. In addition, these hardy organisms must survive the abrasive action of moving sand and gravel.
- Collect pictures of rocky shores. Compare pictures of windswept trees on exposed rocky shores, and trees on protected rocky shores. Windswept trees are often short and stubby and appear to have a rather severe "hair cut" that slants upward from the open ocean.
- Ask the following question: Imagine yourself looking into a tidal pool on a surf-swept rocky shore. you kneel down to get a closer look at the beautiful seaweeds and brightly colored sea stars. Suddenly you look up and see that a huge wave is about to wash over you. What would you do? Would you run? Why or why not? What else might you do? Lead the students to realize that if the wave is too close, and they attempt to run, the wave would simply wash them into sea. Sometimes the best thing to do is crouch down and make yourself as small and low as possible, like a barnacle or sea star. Attempt to hold onto or straddle a rock, or even seaweeds. Let the wave simply wash over you. Then run for safety. Stress the fact that they should NEVER explore near a surf-swept shore without a knowledgeable adult, and then ONLY WITH GREAT CAUTION!
overview of each chapter
page 13, 14
sample lesson, tidal pools
page 182, 183, 184, 185, 186, 187, 188, 189
sample lesson, adaptations of surf-dwelling rocky shore animals,
page 222, 223, 224, 225
sample lesson, vertical zonation,page 202, 203