What are tide pools?
Every day, the coasts experience two high tides and two low tides, caused by the pull of the Moon’s gravity on the Earth’s waters. Although the Moon’s mass is relatively small, its proximity to us gives it some influence over the liquid water on Earth’s surface. The Moon’s gravity, along with the rotation of the Earth, create the tidal force, which leads to the formation of two high tide “bulges” on either side of the Earth.
As the Earth spins on its axis, a coastal location will pass through the “bulges” twice a day, causing the two high tides. When it’s not in a “bulge,” the coast experiences a low tide.
High tides and low tides mean that the ocean continuously rises and recedes from the coast, but uneven ground near the ocean can trap pockets of water at low tide. In these pockets of water, known as tide pools, a wide variety of marine life adapted to survival there can be found.
What lives in tide pools?
Inhabitants of tide pools are generally small and hardy, as they must be able to survive exposure to sun, low oxygen, and land-based predators for hours on end. And when the high tide arrives, they have to keep themselves from being swept away by the waves.
Depending on the location, creatures living in tide pools may include snails, mussels, anemones, sea urchins, barnacles, and more.
The tide pool animals are accompanied by a wide variety of plant and algae life. Again depending on the location, seaweed, seagrass, and mangroves can all provide food and shelter to the animals living in the tide pools with them.
What adaptations do tide pool species have?
To avoid all those dangers previously mentioned, the animals and plants living in tide pools have developed unique adaptations.
Sea urchins, for instance, are animals related to sea stars and sand dollars. However, they are most noticeable for the sharp, needle-like spines that protrude from all sides of their body. When the tide pool is exposed at low tide, those spines can act to deter predators from taking the sea urchin for a meal.
Meanwhile, sea stars themselves use their many tube-feet to suction themselves tightly onto rocks and other surfaces. At high tide, this allows them to hang on to their habitats as strong waves wash over the tide pools.
Moreover, seaweed, which do not have roots like typical plants (they are technically algae), attach themselves to rocks using “holdfasts.” These rope-like structures anchor the seaweed like the sea stars’ tube feet, preventing them from being washed out to sea at high tide.
Are tide pools under threat?
Unfortunately, climate change poses serious threats to tide pools and their inhabitants. As global warming causes a rise in ocean temperatures, species may need to move their habitats to adjust. This, however, can lead to invasive species entering ecosystems and harming the native species there.
In addition, the oceans’ increasing acidity from rising levels of carbon dioxide can have troubling effects, as they decrease the amount of carbonate ions available. A study of tide pools on the California coast showed that calcifying organisms—creatures like mussels and oysters that need carbonate ions to make shells and skeletons—are becoming more susceptible to corrosion. If ocean acidification continues, those creatures’ calcium structures are at risk of dissolving.
Tide pools are known to us today as diverse habitats full of ue forms of life. However, they remain vulnerable to human-made threats, and it is important to stay aware and take action to protect them and their inhabitants for the future.