Mare TG Rocky Seashore

THE MOST EXCELLENT MARE TEACHERS’ GUIDE TO THE ROCKY SEASHORE by Dr. Robin Milton Love Introduction Did you ever notice that there are inside a crevice. There’s dripping and some things that everyone loves? streaming water, of course, and birds For instance, everyone on Earth loves calling and flying. But sometimes, if you oatmeal chocolate chip cookies. The truth are real quiet and put your ears close to is that for even the most humble among the rocks, you can also hear crabs us, if you give us an oatmeal chocolate walking, algae swishing in the pools and chip cookie, our fish flopping. lives are vastly SERENDIPITY And then there enriched. are an almost The rocky Trips to the intertidal are almost always excursions into infinite number intertidal zone the aesthetic. Very early one February morning I was of textures; exploring a pool at San Simeon (in central California). My is the oatmeal nose was running, my boots were filled with cold water and ranging from the chocolate chip the fog was in, muting all colors to dull browns, greens and sticky tentacles cookie of grays. The ledge I was examining was covered in fleshy of sea anemones, marine habitats algae, which totally obscured the underlying rock. I lifted the sharp spines of and you are algae up and on the newly-exposed surface was a Hopkins sea urchins, Rose nudibranch, a sea slug which is covered with jillions of indeed cute little protuberances and colored a remarkable cerise. knobbled skins fortunate to be The contrast between the muted, fog-shrouded rocks and of sea stars to among those this extravagant creature was wondrous. the almost able to explore These brief, subtle and quite unacademic moments, are unnaturally its wonders. marvelous gateways to discovery and curiosity. They are the silky skins of sea reasons you and your students will return to the tidepools Years from now again and again. As you practice slowing down and looking hares and other (when you are a closely, tiny and wonderful worlds will unfold more and sea slugs. And grouchy more frequently. mixed through octogenarian), all of this is that your one fond memory may be those remarkably thick, low-tide smell, redolent wondrous days spent among the rocks with life, death and decay. I would and crannies. mention the tastes in this habitat (a great And why is that? What is it about this many of the plants and animals are habitat that elicits such a response? edible), but we feel it’s better to look than Perhaps it is because the rocky intertidal to cook. is such a sensual, aesthetically pleasing What we are going to do in the experience; it engages your senses. First, upcoming pages is walk you through the as you look around, there is the sheer riot intertidal and talk about what it’s like of life that covers every surface and physically, what major organisms live pervades every crevice. And not only are there, how they cope with the physical there lots of living organisms; there are world and what impact humans have on often hundreds of different kinds. this remarkable environment. Frequently, the plants and animals will themselves be covered or invaded with Okay, What's It Like? other organisms and occasionally even First, you should realize that the rocky these will be homes for still more tenants. intertidal zone is a habitat with an Or perhaps it’s the sounds you hear if attitude. It is no picnic living there. When you are real quiet and sort of hunch down it comes to marine organisms, this is not a place for pencil-necked geeks. Of course, water (water tends to go into it). How can all organisms in all other environments our organism cope with these very have it tough; but most often they have to different environments? overcome living (biotic) challenges, like Then there is wave shock, the finding food, avoiding predators, or remarkably powerful force of crashing resisting diseases. Organisms in the rocky water. As I write this, I can look out the intertidal face these problems, of course, window of the Marine Lab and see waves but they also face the added dimension of roll over an intertidal ledge, then smash inhabiting an environment with extreme into a cliff, sending water 10 feet high. non-living (abiotic) conditions. How does our typical organism not get If you think about it, in one respect the swept away or crushed? Waves also help intertidal zone is totally different from all send water splashing up into the high other land and water communities. It is intertidal. But, unlike tides, they do this exposed to water part of the time and dry unpredictably. Organisms high up in the at other times. The equivalent on land intertidal can’t depend on large waves would be if, say, a redwood forest was in every day and must be able to withstand air part of the time and in a vacuum the prolonged periods of drying. rest. Because the water environment is so There are other potential problems different from the air, intertidal organisms from the environment. In polar or near- face an almost bewildering range of polar regions (i. e. Alaska or conditions in the course of a day, a season Newfoundland), ice forms on the shore or a year. lines, then scours the rocks as it moves. In What kind of conditions? Well, a much of the world, sand is carried onto typical member of the rocky intertidal (it the shore in summer (when the waves are could be a mussel, sea star, alga or crab) gentle), then carried offshore in winter faces a range of abiotic challenges. First, (with storm waves). In the process, some as the tide rises and falls, it is alternately rocky areas are sanded in during part of drenched and dried. When this happens the year, burying the intertidal organisms. the organism’s temperature can decrease Okay, this is obviously a pretty tough rapidly as cold water splashes its sun- place to live. Why don’t we talk a little warmed body or, alternatively, it can heat about the major factors that control what up as it is exposed to the air. This latter organisms live where in the intertidal. often happens in hot, tropical areas. Breathing is also going to be a problem, as The Big Factors what works in water (gills) may not be Tides very effective in air, and what works in Obviously, tides are a major (perhaps air (lungs) just can’t cut it in water. the major) controlling force in many Our friendly creature also has a intertidal habitats, because they help problem when it rains and it is pelted by dictate how long organisms are under fresh water. Remember that experiment water. Tides are rhythmic, predictable, you did in 10th grade biology? The one periodic changes in the height of a body where you put a nice crisp stalk of celery of water. The tides are caused by a in a glass of saltwater and the next day combination of the gravitational pulls of the stalk looked completely limp. Then, the sun and moon and the centrifugal you put the limp stalk in freshwater and, force caused by the rotation of the Earth/ voila, the stalk became stiff again. A body moon system. Throughout the year, tides responds differently when in salt water vary in their heights, and the highest (water tends to leave it), then in fresh highs and lowest lows occur together 2 during the new and full moons, when the several factors and the most important is moon and sun are directly aligned with the size of the area a wave travels through the Earth. These extreme tides are called without being hindered by islands or spring tides, which comes from the Old undersea ridges. The more wide open an English word springen, meaning to jump area, the larger the waves that can be or move quickly. Spring tides occur every generated. If you stand on the shore two weeks and alternate with less anywhere from Cape Flattery, northwest extreme neap tides. Washington to Pt. Conception in central Tidal patterns (how often highs and California, there is absolutely nothing lows occur within 24 hours) and ranges between you and the Aleutian Islands. (the difference between high tide and low That is a long way and it allows some tide water levels) differ in different parts fearsome waves to form. Of course, wind of the world. Some areas such as much of velocity is also important, which helps the east and west coasts of the United explain why waves tend to be higher States, usually have two high and two during storms. On much of the Gulf low tides per 24 hours. These are semi- Coast, waves tend to be small, and they diurnal tides. On the other hand, Gulf are a factor only during hurricanes and Coast states tend to have one high and other storms. Because waves have such a one low tide (diurnal tides) during the profound effect on sea life, any protection same period. Tidal ranges vary from their power alters the makeup of the dramatically, depending on the shape of animals and plants living in the habitat. the water basin the tides flow through. For instance, along the Pacific Coast, The narrow Bay of Fundy, in New wave-swept rocks are home to the Brunswick, Canada, has tides of about 50 powerfully-built sea star Pisaster (or ochre feet. Remember, this does not mean that star), which can hang on even when the water goes inshore 50 feet.

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