Tidepool Information

Tidepools form on rocky shelfs where the water wears away holes in the rocks. These rocks are submerges during high tide, but at low tide, they are uncovered. The organisms that live in tidepools are marine organisms that must survive in this harsh environment. 

The tidepools can be separated into different zones based on how close to or far from the ocean they are. The zone that is far from the ocean and is almost never underwater is called the splash zone. As you move closer to the ocean we have the high tide zone, the mid tide zone, the low tide zone. The zone that is always underwater is called the subtidal zone, and is not technically part of the tidepools. 

Life in the Intertidal Zones by the Monterey Bay Aquarium (Article)

Seasons in the Sea (Article)

This section is under construction! Thank you for your patience!

Cnidarians (Anemones, Jellies):

Swimming Anemone (Video)

Crustaceans (Crabs):

Hermit Crab Leaves Glass Shell (Video)

Echinoderms (Sea Cucumbers, Sea Stars, Sea Urchins):

Sea Stars Eating Mussels (Video)

Sea Urchin Eating (showing teeth) (Video)

You’ve probably heard that the moon controls the tides, but how exactly does that work? Well it all starts with gravity. The earth has its own gravitational pull, but so does the moon and the sun. Even though the sun is way bigger than the moon, the water on earth is more affected by the moon because it is much closer to us. 

So the water on earth is being pulled toward the moon. But what about the other side of the planet? Here’s where things get a little bit complicated. The earth is rotating, and the water on earth rotates with it. If you were to spin an object with water on it, the water would fly off in all directions. This is an example of centripetal force, which is the force that pulls outward, away from the center of rotation on a spinning object. Another example of this is the carnival ride where riders stand along the walls of a quickly spinning room. Even if the floor is removed from the ride, the riders will not fall out and will stay stuck to the walls due to the centripetal force pushing them outwards.

This is what happens to the water on earth. Because of the earth’s rotation, the water wants to fly outward into space. However, gravity keeps it on the planet so our water doesn’t spin away. Now let’s add the moon to our equation. The moon is pulling on the water on earth, which wants to spill out into space but is being kept on earth by gravity. This causes the earth’s water on the opposite side of the moon to also bulge outward, similarly to the earth’s water on the same side of the moon. This is why we have two high tides and two low tides in a single day. The earth rotates through these bulges of water each day. 

Tides are how we see the water getting higher and lower along the shore, but what about water moving around on a global scale? This is where global ocean currents come in. Ocean water is moved around by 3 things: temperature, wind and salinity (or salt). Cold water is more dense than warm water. Its molecules are closer together, and therefore sink below the warm water. Salty water is also more dense than less salty water because it has more dissolved molecules in it. The last thing moving the water is the wind. The wind mostly moves surface waters, but its motion pulls on all the water, even at lower depths, causing deep water to slowly move as well. 

The sun warms the surface water. As it does, some of that water may evaporate, leaving behind its salts and making the water saltier. This saltier water is more dense so it will slowly sink away from the surface. As it sinks farther from the sun, it cools and sinks even further. All of this is happening as the wind pushes surface waters, causing currents. If cold water is always sinking, and warm water is always rising, shouldn’t the entire ocean be nice and warm? Underwater topography also changes currents, especially their temperatures. Many places experience upwelling, which is when wind pushes warm surface water away from the shore, causing cool deep water to rise to fill that gap. With this constant circulation of warm water sinking, and cool water being pushed to the surface, our oceans are constantly moving on a global scale.

Tide Predictions for Santa Cruz, NOAA

Tides, by NASA

What Causes Tides, by NOAA

How Do Oceans Circulate? by Crash Course Geography on Youtube

How Ocean Currents Work (and How We Are Breaking Them) by Be Smart on Youtube

What is Upwelling? by NOAA

The Missing 24-Limbed Animals That Could Help Rescue the Ocean’s Forest