Intertidal Invertebrate Migration: Finding the Motivation to Move in the Rocky Intertidal



Batillaria minima
Batillaria experiment
Gastropod Movement

Mytilus edulis
Mytilus experiment
Zonation Patterns
Juvenile Resettlement
Byssal Threads

Rocky Intertidal



The Author

Explore the movement of the blue mussel, Mytilus edulis in the rocky intertidal in Nahant, MA and the movement of the tiny snail, Batillaria minima in a tide pool in Bermuda



Most organisms in the rocky intertidal are sessile or sedentary*. Almost all of the algae have holdfasts to attach them to the rocky surface. The most common fauna in rocky intertidal habitats are probably mussels and barnacles, which are both sessile. There are also usually a number of snails or sea stars which are both known to move seldom and very slowly. Crabs are the most mobile creatures found in the intertidal, scurrying about in search of food and shelter. Movement in the intertidal is a fascinating concept, especially for the sessile or sedentary organisms. First of all, movement across the rocky substrate is a very energy intensive process. An organism must have some motivation to expend such energy to venture out in the rocky intertidal. Also, the surface can drastically change in a very short distance, a snail living in a tide pool may have to travel only a few or several hundred meters to find another tide pool, and it may not find the algae it prefers to eat. Space is limiting in the intertidal and once an organism has secured a spot, why should it embark on the difficult task of finding another? Organisms moving in the intertidal also risk desiccation. If the sun is out, there’s no guarantee of finding shelter again in the patchy surface of the rocky intertidal once you leave a sheltered spot. Other than the obvious reason for movement, search of food (mussels are filter feeders), how and why would a sessile organism like a mussel move itself within the intertidal? Or why would slow-moving snail travel across a tide pool? These are the questions I address in this website. My Ecology of Atlantic Shores class took several trips to the rocky intertidal in Nahant, MA where I was able to study the zonation patterns and larval settlement of the blue mussel, Mytilus edulis. We also spent a week in Bermuda, and while I was there I managed to get away from the snorkeling long enough to explore the movement of some tiny snails, Batillaria minima, within a large tide pool.


*underlined words can be found in the Glossary


    © 2002 Laura Brentner, for educational purposes only