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There are four intertidal “zones” that are based on exposure during wave action. Presence of water, air and water temperature, wave action, variation in saltiness and exposure to light determine what organisms live happily in each zone. Some organisms have a low tolerance and are found only in one zone, while others have a greater tolerance and are found in several zones.
Dave and Tim and I had a great time tidepooling in Oregon this past June. You can "Tidepool" or "rockpool" by visiting the rocky intertidal zone along a coastline. The intertidal zone is the region where the ocean meets the land, meaning that during high tide the area is covered in sea water, and during low tides, the water recedes. Low tide... is when the magic begins along the Pacific coast. Low and high tide times are listed on the buildings in state and national parks. Being aware of the rising tide is important. It is really easy to get lost in your curiosity and wonder while climbing in and around the rocks. We found, the best time to tide pool was early in the morning. We would take our coffee and sit on the bench overlooking the ocean for awhile and then begin our climb down onto the monstrous black rock formations that decorate the Pacific coastline.The 360 miles of Oregon's Pacific coast include beaches, dunes and estuaries(where the tide meets the stream), but the majority is rocky, steep cliffs, small islands, sea stacks that have eroded into arches and caves. The coolest part is that most of the coastline is undeveloped and open to public access.
Here is a look at some of the inhabitants of Oregon's coastal tidepools:Green sea anemones look like those rubbery, sometimes slimy feeling weird things you find in the toy department between the Flarp and the Woopie Cushions. This green plantlike creature is actually an animal with algae plants living inside it. In this win-win relationship because the algae get protection from snails and other grazers and don't have to compete for living space, while the anemones get extra nourishment from the algae in their guts. The anemone's green color is produced by the animal itself, not the algae that it eats.
Just like their jellyfish relatives, sea anemones use their tentacles to sting and retrieve prey. Small fish, open snails, and other intertidal animals are caught by the tentacles, pulled into the mouth, and eaten.
If you see an anemone with tentacles tucked inside while underwater, it is probably eating.
A closed Sea Anemone---probably eating |
Poking or stepping on anemones causes them to spit out valuable water they need to stay hydrated during low tide so it's important to walk gently.
Another tidepool inhabitant is the Gooseneck Barnacle. Gooseneck Barnacles, are crustaceans that live attached to hard surfaces of rocks in the ocean intertidal zone. These barnacles can live 20 years or more. They use their feathery feet, called cirri to feed and breathe.
Another barnacle we found is the Acorn Barnacle. Each barnacle has a slightly different texture and door shape. Opening and closing, barnacle’s curved legs sweep the water for food. We found some barnacles submerged in a tidepool on top of the rocks and watched them open and close. If a patch of barnacles grow long enough and big enough, they’ll crowd each other and begin to grow upwards only where they become tall and narrow.
empty acorn barnacle |
Acorn barnacles |
taller gooseneck barnacles |
here you see the "neck" of the barnacle |
limpets |
Gooseneck barnacles |
Most sea stars have spiny skin and five arms, although some can grow as many as 50 arms. The arms are covered with pincer-like organs and suckers that allow the animal to slowly creep along the ocean floor. Light-sensitive eyes on the tips of the arms help the sea star find food.
Sea stars eat mollusks such as clams, oysters, and snails. The sea star eats by attaching to prey and extending its stomach out through its mouth. Enzymes from the sea star’s stomach digest the prey. Sea stars occupy every type of habitat, including tidal pools, rocky shores, sea grass, kelp beds, and coral reefs. Some sea stars even live deep in sandy beaches.
Sea stars cannot survive if they are exposed to air or sun too long. They cannot get too warm or unattached from the rocks so pulling them off the rocks will end their lives. They are attached so securely that you would have to use something to pry them off.
Here is another cool creature from the tide pool habitat.
How do they stay attached to the rock when big waves crash? Amazingly, the underside of the chiton has a deep slit inside the outer edge where the gills are located with a muscular foot in the center. The middle of this foot is pulled up while the outside edges seal, creating a suction that clamps the animal down. They move by relaxing the suction and moving the foot.
Weird right!?
California mussels produce a liquid adhesive that allows them to stick to hard surfaces. Exposure to the seawater makes the adhesive solidify.
Attached together, the mussels form beds of hundreds in the intertidal. Since the mussels are bluntly pointed on the bottom, there’s some space between them even when the sides are packed together that is a haven for many animals, protecting them from crashing surf at high tides and drying sun at low tides, as well as protecting them from many predators.
Although hermit crabs do venture into deeper waters,they are mainly found in coastal waters where there is more food and places to hide. We found hermit crabs in the quiet tidepools that formed on the tops of the large rocks. The dimples in the rock formations hold water in them when the tide went out. These peaceful areas don't see water again until the tide comes back in.
As a hermit crab grows, it needs larger shells. A large hermit crab in a too-small shell won’t be able to pull itself all the way into the shell, leaving it exposed to predators.
quiet dimples in the rocks |
As a hermit crab grows, it needs larger shells. A large hermit crab in a too-small shell won’t be able to pull itself all the way into the shell, leaving it exposed to predators.
Hermit crabs are omnivours that eat pretty much anything they can find in the water. Small fish and invertebrates including worms, are the most common prey for the hermit crab along with plankton.
Due to their small size, hermit crabs have many natural predators which includes sharks, fish, cuttlefish, squid and octopuses.
Due to their small size, hermit crabs have many natural predators which includes sharks, fish, cuttlefish, squid and octopuses.
quiet tidepool on top of a rock |
Peek a Boo |
thousands of these small hermit shells wash up in parts of the tide pool areas |
There are also plants that live in the tide pools. Rockweed, sea palm, sea lettuce, sculpins and sea weed are all found in the tide pools of Oregon.
What may look a pink rock is one covered with coralline red
algae. I saw these red rocks while hunting for the elusive seastars. While not a coral (which are animals), it resembles some corals.Unlike land plants, water plants lack true roots, stems, leaves, and flowers. They are a safe place and nourishment for small creatures. We see, once again, how all living things (including humans) NEED and DEPEND on other.
Though the rocks and waves may look rugged, the rocky shore habitat is fragile. Rocky shore creatures like green anemones are at risk from coastal development and pollution (including waste oil and agricultural runoff). And some tide pools are in danger of being "loved to death" by visitors. Tread lightly as you explore tide pools to avoid crushing plants and animals, and never take creatures from their habitat.
Also, if children are watching cartoons or programs where animals are removed from their habitats, please explain why that may be happening OR tell them it is wrong. I tried to use a video from Peppa Pig(my granddaughters favorite cartoon) where her family was rock pooling but they had buckets and were removing the animals. It is important that we know what our children are watching. I have, many times, told my students that I had a problem with what we were reading or watching. I tell them my reasoning and we discuss it.
Ahhhhhh |