The Light Bulb Tunicate forms small colonies of zooids connected by creeping stolons. Each individual has a cylindrical shape and is divided into three sections: thorax, abdomen, and post-abdomen. The tunicate is transparent with a bluish hue, sometimes showing pink, and can grow up to 5 cm in length. Key identification features include:
Up to 15 buccal tentacles
13 to 17 rows of visible pharyngeal stigmata
A distinct white or bluish vertical endostyle line
Close and prominent siphons, with the atrial siphon often underlined by a blue-purple margin
Visible purple stomach and intestine in the lower part of the zooid
Clavelina dellavallei is native to the eastern Atlantic Ocean and the Mediterranean Sea. It thrives on rocky bottoms, attaching to rocks, sea-fans, or seaweeds. These tunicates inhabit depths ranging from one meter to 50 meters. They are commonly found in areas with rich planktonic food sources.
Feeding Mechanism: These tunicates filter water to feed on plankton. They ingest water and food through the entrance siphon and expel water and waste through the outlet siphon.
Reproduction: Light Bulb Tunicates are hermaphrodites. They retain eggs internally until they hatch. Larvae swim freely in plankton before attaching to a rocky substrate to undergo metamorphosis, which lasts 2 to 3 days.
Pollutant Accumulation: They can accumulate significant amounts of copper and lead in their tissues, especially in harbors where they absorb components from anti-fouling paints on boat hulls.
Genetic Diversity: Scientific studies reveal important genetic differences within the species depending on their habitat. Those living inside harbors are generally larger than those in open waters.
In Gozo, the Light Bulb Tunicate can be seen at various dive sites. One notable location is the entrance to Coral Cave on Gozo’s west coast, where they can be found at a depth of 18 meters. Divers exploring these areas can appreciate the unique beauty and ecological significance of Clavelina dellavallei while enjoying Gozo’s vibrant underwater landscapes.
