Marine zooplankton are among the most diverse and abundant organisms on earth. Despite a great wealth of knowledge and research on their ecology, the processes promoting coexistence and maintaining their high diversity worldwide are poorly known. In order to understand the processes underpinning coexistence among marine zooplankton, we investigated the existence and degree of niche separation within two pairs of taxonomically...

Size, growth, and density have been studied for North American Pacific coast sea urchins Strongylocentrotus purpuratus , S. droebachiensis, S. polyacanthus , Mesocentrotus (Strongylocentrotus) franciscanus , Lytechinus pictus , Centrostephanus coronatus , and Arbacia stellata by various workers at diverse sites and for varying lengths of time from 1956 to present. Numerous peer‐reviewed publications have used some of these dat...