Their hard shells (tests) are round and spiny, usually from 3 to 10 cm (1 to 4 in) across. Predators of purple sea urchins include those for red sea urchins but, because purple sea urchins are common in the intertidal zone, predators also include sea gulls, oyster catchers, and raccoons. The Purple Sea Urchin is one of the most common sea urchins found on Sydney's coast. Factors that have decimated the species include warming sea temperatures and invasive fish that eat algae, depriving the urchins of a diet staple. Ali Bouzari is a biochemist and trained chef. Sea urchins hit all the taste pleasure points – salt, sweet and umami. In Northern California, the problem began with a sudden, unexplained die-off of sea stars, the urchin’s main predator. Due to higher water temperatures, the Blob has negatively impacted many underwater ecosystems like that of the purple sea urchin, which now face starvation and overgrazing. In a healthy ecosystem, the purple sea urchin is certainly no villain. Colours can vary so dramatically in this species, from light olive green to pink to a dark purple, that the Purple Sea Urchin was once thought to be three separate species. Sea urchins (/ ˈ ɜːr tʃ ɪ n z /), are typically spiny, globular animals, echinoderms in the class Echinoidea.About 950 species live on the seabed, inhabiting all oceans and depth zones from the intertidal to 5,000 metres (16,000 ft; 2,700 fathoms). Meanwhile, in the Mediterranean, the purple sea urchin population is currently in a near threatened state. When kelp is abundant and underwater forests are rich with nutrients and sea-life, urchins most often dwell in crevices, mainly eating loose bits of kelp that drift within their reach. In a lot of places, sea urchins are overfished, but that certainly isn't the case off the coast of California, where there's such an overabundance of purple sea urchins that it has become an aquacultural concern. The researchers examined urchin populations inside and outside marine reserves, where protection from fishing should have enabled urchin predators to rebound and control their populations. Sea otters are able to reduce sea urchin populations to levels unsuitable for commercial or recreational shing, but apparently not to levels that Again, the underlying cause is an imbalance in the ecosystem. The purple sea urchin population skyrocketed. "We predicted that by protecting these areas we're increasing the number and density of urchin predators that will then control urchin populations the purple sea urchin, which isn't. Sea urchins (/ ˈ ɜːr tʃ ɪ n z /), are typically spiny, globular animals, echinoderms in the class Echinoidea.About 950 species live on the seabed, inhabiting all oceans and depth zones from the intertidal to 5,000 metres (16,000 ft; 2,700 fathoms). Rogers-Bennett said a warming ocean is believed responsible for upsetting a natural balance of ocean predators that has allowed the purple sea … Identification. "So with the increase in purple sea urchins, what we've seen is a dramatic reduction in kelp cover, primarily in Northern California. https://sanctuaries.noaa.gov/vr/olympic-coast/urchins-diver.html A purple sea urchin, strongylocentrotus purpuratus. ... Sea Urchin Predators and Prey.