Tidal Pool Exploration

A tidal pool is simply a depression on the shore containing water which was left behind when the tide went out. These pools provide moisture and protection for marine plants and animals when they are uncovered by the tide. Here are a few things to look for to get you started but you will probably find many more mysterious creatures.

When exploring the intertidal zone watch your step, the seaweed covered rocks are slippery. Be careful that you don't get cut off from the shore by the incoming tide. The best time to explore is as the tide is going out.

Periwinkles

Sometimes called marine snails these are probably the most common animals found on the shore or in tidal pools. Their shells may be dark brown to shades of orange or red with many interesting patterns. A slimy, muscular foot is used to move and anchor the animal. A periwinkle can completely withdraw into its shell and close its door (operculum) when it is disturbed.

Hermit Crab

If you see a periwinkle shell "running" quickly over the bottom of a tidal pool it's probably not a periwinkle at all but a hermit crab. Unlike most crabs which are hard all over, hermit crabs have a soft abdomen. This makes them vulnerable to predators so they protect themselves by using discarded shells of other animals as a portable "house".

Sea Anemone

These animals are related to jellyfish. They can be found attached to the bottom of a tidal pool. Sea anemones have a ring of tentacles around their mouth. These tentacles contain microscopic stinging cells which shoot out when disturbed to embed themselves in whatever caused the disturbance and inject a toxin. The anenomes found on the shore in our region are silver-spotted anemones. They are nearly translucent with a silver-white spot at the base of each tentacle. The sting they produce is not strong enough for humans to feel.

Seaweed

In and around a tidal pool and covering the rocky shore you will find many different types of seaweed (also called algae). Seaweed provides food and protection to the animals living on the shore. It must be verystrong and flexible to survive in this environment. Wave action on seaweed is similar to a 1440 kph (900 mph) wind on an oak tree! (The highest winds ever recorded were from the top of Mt. Washington, NH - approximately 380 kph/240 mph). The easiest way to distinguish seaweed is by the colour. The major groups of seaweed are the red algae, green algae and brown algae. The browns are by far the most abundant in the north eastern North American shoreline. The reds are more common in deeper water but can be found in tidal pools.