Exploring the Intertidal Zone

The intertidal zone is one of the most dynamic and extreme ecosystems on Earth. Found between the high and low tide marks, this ever-changing environment is home to some of the most resilient and fascinating marine creatures. With tides shifting twice a day in British Columbia’s coastal waters, the species living here must constantly adapt to periods of complete submersion and exposure to the elements.

A Hotspot of Biodiversity

This transition zone is a biodiversity hotspot, supporting a wide range of species, from algae and sea stars to mussels and barnacles. It also plays a crucial role in the ocean’s ecosystem, mixing nutrients from both land and sea and providing a habitat for migratory species like shorebirds.

As you move through the different levels of the intertidal zone, you’ll notice variations in marine life. The highest areas, which receive the least water, are dominated by small barnacles, while lower levels, which stay submerged longer, host a greater variety of life, including pink algae, mussels, anemones, and tide pool sculpins.

How Do Intertidal Species Survive?

Life in the intertidal zone is not easy. Organisms must endure fluctuating temperatures, the risk of desiccation (drying out), and predation from birds, otters, and other marine species. To cope with these challenges, intertidal creatures have evolved remarkable adaptations:

• Protective Shells: Barnacles, mussels, and limpets close their shells tightly to retain moisture and safeguard against predators.
• Camouflage: Sculpins and sea stars blend into their surroundings, making them harder to spot.
• Behavioural Adaptations: Many species retreat into tide pools, burrow into sand, or cling tightly to rocks to withstand changing conditions.
• Toxic or Noxious Defenses: Some organisms, like sea anemones and nudibranchs, produce toxins or stinging cells to deter predators.
• Closing Up or Sealing Off: Barnacles and mussels tightly close their shells, while anemones contract to reduce exposure.
• Spines & Other Physical Barriers: Urchins, some sea stars, and certain snails have spiny exteriors to make themselves harder to eat.

Why Is the Intertidal Zone So Important?

The intertidal zone is considered one of the most productive ecosystems on Earth due to its nutrient-rich waters. Upwelling currents bring deep-sea nutrients to the surface, mixing with freshwater and ocean water to create a thriving food web. Various microhabitats like rocky crevices and tide pools give many species places to live and interact, which helps support rich biodiversity.

We discuss all about the intertidal zone on the newest episode of the Prince of Whales PODcast! Learn more about this incredible ecosystem on Episode 17: