Purple Sea Urchins, scientifically known as Paracentrotus lividus, are a fascinating marine species commonly found in the Mediterranean Sea and the eastern Atlantic Ocean. Particularly abundant in the western Mediterranean, these sea urchins thrive in waters with winter temperatures ranging between 10 and 15°C. Gozo, with its rich marine biodiversity, is an ideal location to observe these intriguing creatures.
Identifying a Purple Sea Urchin is relatively straightforward. They have a circular, flattened test (shell) that is typically greenish and can grow up to seven centimeters in diameter. The test is covered with long, sharply pointed spines, usually purple but sometimes varying in color from dark brown to light brown or olive green. The spines, arranged in groups of five or six, give the sea urchin its distinctive look.
Paracentrotus lividus exhibits several unique characteristics. The sea urchin’s tube feet, organized in small arcs, aid in mobility and feeding. It has numerous lateral cerata with smooth surfaces and an inflated appearance. The central digestive gland lobe, visible through each ceras, is thin and brown, splitting into terminal branches at the tips. The tips of the cerata are bluish-white and iridescent, adding to the sea urchin’s vibrant appearance.
Purple Sea Urchins inhabit the sublittoral zone, typically found from just below the low water mark to depths of 20 meters. They prefer rocky substrates and are often seen in seagrass meadows of Zostera marina and Posidonia oceanica. These sea urchins can dig into soft rocks to create protective cavities, especially in shallow or exposed waters. They are usually nocturnal feeders but may adapt their feeding habits based on predator activity.
An interesting fact about Purple Sea Urchins is their reproductive behavior. They aggregate for spawning, releasing gametes into the water column. The larvae become part of the zooplankton for about 28 days before settling and undergoing metamorphosis. This species plays a crucial role in their ecosystem, significantly impacting the benthic community through their feeding activities.
