Written by: Juan Carlos Cruz Dias
Coasts are continually in motion and are always a mixture of salt water and earth.
The boundary between the ocean and land is in constant flux due to the tides. In the rocky areas along the shore the waves flood the pools made of rock only to slowly trickle out as the tide recedes. The many species these pools harbor are revealed as the waves ebb; some have become trapped there, while others have made this rocky habitat their home.
Hundreds of species live in perfect harmony in these small areas, including species that are very tolerant as well as very susceptible to human activity. Fortunately, the beaches in Osa still have an endless amount of pristine pools along the coast, and Piro beach is a perfect example of this.
The species found here must be highly adaptable to changes in water temperature, salnity, and dissolved oxygen, like sea anemones.
These benthic species can be as small as 1 centimeter and as large as 2 meters; the species in the tide pools are the smallest. Their tentacles make them seem more like flowers rather than the tools used to capture small fish and invertebrates to feed upon.
Sea slugs are mollusks without shells that have adapted to a benthic lifestyle, living off of small invertebrates that they patiently search for along the sea floor. They are poisonous animals and hardly have any natural predators, thus having a shell is not necessary.
Sea urchins, on the other hand, are omnivores that search for any kind of organic matter along the ocean floor. Their calcium structure forms spines, acting as a very efficient defense mechanism against predators.
Sea snails are the group with the most abundance and diversity within the mollusks, comprising over 50 per cent of the 100 thousand known species of mollusks. Within the Cypraeidae family, shells are extremely smooth and shiny due to the fact that it is always cloaked by a protective cover while the animal is alive (Photo 8).
The Christmas tree worm is part of the Serpulidae family, and it inserts itself into living coral, only leaving visible two spiral crowns of diverse and intense colors . Their name is derived from their form and coloring. These plume like structures are used to capture suspended particles of food and plankton in the water.
The tide pools are Windows to the sea because they show us a glance of the endlees number of species that live in the ocean but also that are complete ecosystems that we have to protect from human activities, pollution and development.
So the next time you go to the beach and find a tide pool pay look closely, maybe you can see one of these incredible animals, and of course if you ever have the opportunity, come and visit us in the Osa: where the rainforest meets the sea.