Stories of the Tides Often times, field guides are great for identifying unknown intertidal plants and animals. However, interesting stories about these organisms are left out. The following compilation of information comes from stories shared verbally and in written text. These stories are great to tell during guided inquiry and even in the classroom before a fieldtrip to the tidepools. Knowing the information or having it handy to share with students will make the tidepools come alive. Phylum Porifera - filter feeding colonies Sponges Sponges may look like simple plants, but many are surprised to find out that they are animals. They are relatively simple, but can grow in all shapes and sizes depending on where they live. Sponges growing in calm water tend to have more tube and volcano like structures. In the intertidal however they will often grow very flat due to high surf action. Sponges use many tiny holes called ostia to suck in seawater and shoot it out larger volcano openings called oscula. While the water is within the sponge it filters out all of the tiny organic particles, like bacteria, to feed and other nutrients needed for growth. That would be like humans surviving off of air alone! Phylum Cnidaria - animals with stinging cells called nematocysts. These nematocysts work like high-powered barbs at the end of coiled ropes that shoot off when touched. These allow the animal to take hold of its food or defend itself. Nematocysts found in the intertidal will most likely not hurt you. Feel free to touch anemones, but it would be wise not to taste them. Giant green anemones – Anthropleura xanthogrammica There are many varieties of anemones in the tidepools, and while they all have special characteristics that separate them by species, they share some really cool characteristics that make them similar. Most anemones found in the intertidal are green. One may ask why? Green anemones actually have tiny plants that live in their tentacles and columns. The algae plants have chlorophyll pigments that cause the anemone to turn green. The relationship between the anemone and algae is symbiotic, which means that both organisms benefit. Animals, even aquatic ones, require oxygen to breath. Respiration turns this oxygen into carbon dioxide, which the algae then take up and use for photosynthesis, which gives off oxygen as a waste. By hosting the algae within, the anemone has easy access to the precious oxygen. In addition to providing readily available carbon dioxide, the anemone’s body makes it a great home with built in stinging cell protection. If you search the underside of rocks or shady cracks you might be able to find white anemones. These are animals without algae in their bodies. It is not unhealthy; it just does not rely on symbiosis to get any of its oxygen. Cloning anemones/aggregate anemones - Anthopleura elegantissima When these anemones find themselves living alone on a bare rock, they will clone in order to reproduce. The anemone will pull itself apart for about two days until it rips in half. It will continue this process of cloning until it runs out of room. If it runs into another group of aggregate anemones that have been busy cloning as well, war will erupt between the two colonies. The anemones along the battle line will produce what are often called “war clubs,” tentacles that swell up on the ends with nematocysts. These two colonies will fight back and forth until there is a space between them with no anemones inhabiting it. This is why you can see dividing lines between all of the groups of aggregate anemones on the rocks during low tide. Often times these anemones cover themselves with small rocks; these rocks are used in a similar way to sun block, protecting them from the sun and helping them retain water at low tide. Brooding anemones – Epiactis prolifera Brooding anemones come in different hues of colors including bright red. Their bodies are flattened at the base with radialy arranged lines. Unlike the giant green and aggregating anemones, this animal relies on motherly tactics to raise their young. The anemone’s larvae swim out of their mom and position themselves along the flattened base. They stay there until they grow into tiny anemones and are ready to leave the home base. When you flip over a rock look for smaller anemones nearby the mother anemone. Phylum Mollusca – animals with a belly-foot Black turban snail – Tegula funebralis Looking for snails in the tidepools can sometimes be tricky. Don’t be surprised if you pick one up and it’s actually a crab! Hermit crabs are notorious for using black turban snails’ old shell as their home. Snails are part of the “belly-foot” family, meaning that they eat, move, and stick to rocks with their strong, fleshy body. Most snails are vegetarians and feed on algae or seaweed. The white circle on the top of the shells is actually the oldest part of the snail. It can live to be more than 20 years old, which is when it is no longer black on top. Sometimes you will see coralline algae, limpets or smaller snails on the backs of black turban snails as well. Purple olive snail – Olivella biplicata Just like the black turban snail shells, purple olive snail shells in the intertidal are often found with hermit crabs within them. Purple olive snails live in sandy beaches about an inch or so underneath the sand. If a sandy beach is nearby the tidepools you will likely see a hermit crab making one of these beautiful shells into their home. Miwok Indian tribes of the northern California coast and Chumash Indian tribes of southern California’s channel islands used these beautiful shells as money for trade and decorations on clothing and jewelry. Imagine begin able to go out and collect dollar bills on the beach! If you look closely on the shell you will see very fine lines showing the pattern of growth. The oldest part of the snail is at the very top of the spiral. The snail puts on tiny layers each year as it grows more and more. Sometimes people ask how old many of the creatures of the tide pools are. This is a rather difficult question to answer, but we can get some sense by looking at the number of lines on the purple olive snail. Some snails you pick up will have varying patterns. Some of the lines are very straight while others are very jagged. The jagged lines may indicate a rough point in the snail’s life where maybe they were attacked or lived through a rough winter. The smooth lines indicate an easy year for the snail. By reading the lines we get a story of this snails long-lived life experiences. Chitons Chitons have remained virtually unchanged for over 500 million years! There’s one thing that you must remember in the search for chitons: “eight plates are great!” Just like terrestrial pill bugs, chitons have hard plates that protect their body’s “belly-foot” and let them conform to uneven surfaces. A chiton can be motionless and uninteresting to the untrained eye, but if you manage to find one that lets loose from the rock, you’ll discover something interesting and familiar. When removed from the rock, chitons will curl into a crescent moon shape in order to protect the soft foot inside. The Katy chiton is often found exposed during the day, feeding on algae while most chitons are found in crevices and under rocks. Other chitons may remain in the same place for a long time while Katy chitons graze during the day. The gumboot chiton is especially interesting. Unlike smaller species found in the intertidal, the gumboot can be easily dislodged and examined. In the gill chamber beside the belly foot of the gumboot is a small white parasitic worm that has found a safe home. Nudibranchs Keep your eye out for these small creatures. Often overlooked, over one hundred and seventy nudibranchs can be found along Pacific Northwest shores. They are essentially snails with out shells, but often much more colorful than our common garden slugs. They come in a variety of colors including lemon yellow, bright red, orange and even purple! Many nudibranchs are often missed though because they can be translucent in color making them nearly invisible. The name nudibranch actually means “naked gills”. Some species use finger like cerata on their backs for breathing and digesting food! The cerata can also be used for defense. Many nudibranchs feed on the tentacles of sea anemones to steal their nematocysts. Because they have special mucus to protect them, they are not harmed by the harpoon-like stinging cells. The nudibranchs simply gobble them up and sort the stinging cells for all of the cerata. The nudibranchs are then armed with the weapons of their prey! Other nudibranchs lacking cerata have gill plumes located on their lower end. Like every little brother or sister nudibranchs are picky eaters and feed almost exclusively on colorful sponges. Limpets It’s impossible to find two limpets that look identical. Their variety in colors and patterns make searching for them an adventure with something new under each rock. Limpets rely on their powerful suction power to protect them from predators and pounding waves. In fact pounding waves only allow the limpet to hold tighter onto a rock. These simple creatures also have the ability to sense when an enemy, usually a sea star, is around. When the situation arises, they can glide away with their shell hiked up like a big southern bell skirt.