Strongylocentrotus

Strongylocentrotus is a genus of sea urchins belonging to the family Strongylocentrotidae. These echinoderms are commonly found in temperate waters of the North Pacific Ocean and the North Atlantic Ocean. Species within this genus are characterized by their spherical or slightly flattened bodies covered in spines. The spines can vary in color, often ranging from green to purple or brown, and are used for locomotion, defense, and to a lesser extent, feeding.

Several species of Strongylocentrotus are ecologically significant, playing a crucial role in marine ecosystems. For instance, Strongylocentrotus purpuratus, the purple sea urchin, is abundant along the Pacific coast of North America and is a major herbivore, feeding primarily on kelp and algae. Overgrazing by sea urchins can lead to the formation of "urchin barrens," areas where kelp forests have been decimated. Other species, such as Strongylocentrotus droebachiensis, the green sea urchin, are found in both the Pacific and Atlantic and are also important grazers.

These sea urchins are gonochoristic, meaning individuals are either male or female, and reproduction typically occurs externally through the release of gametes into the water column. Their larval stages are planktonic before settling to the seafloor. Strongylocentrotus species are sometimes harvested for their roe, which is considered a delicacy in some cultures. Research into their biology and ecology continues to shed light on their role in maintaining the health and structure of kelp forest ecosystems.