Beadlet anemones (Actinia equina) are sessile marine animals commonly found attached to rocks in the intertidal zone of rocky shores.
Two students want to estimate the population size of A. equina on a specific stretch of a rocky shore.
Which of the following methods could the students use for this estimate?
1, 2 and 3
only 1 and 2
only 2 and 3
only 1