Kelp-craving purple urchins (Strongylocentrotus purpuratus) are contributing to an underwater housing crisis! Kelp are considered ecosystem engineers because they provide food and shelter for many marine species. Due to several disturbances in the kelp forest, this underwater ecosystem in Northern California has been thrown off balance. Without predators to keep purple urchin populations in check (to learn more about urchin predators check out this Creature Feature), these “goats of the sea” are mowing down kelp (seen here, Nereocystis lueketana) in mass quantities, creating urchin barrens.

[Photo by Tristin McHugh and caption by Karli Chudeau]

Filbee-Dexter, K., & Scheibling, R.E. (2014). Sea urchin barrens as alternative stable states of collapsed kelp ecosystems. Marine Ecology Progress Series, 495, 1–25. https://doi.org/10.3354/meps10573