Ascidie Jaune

Overview

Phallusia julinea is a large, solitary ascidian widely distributed across the Indo-Pacific region. Often found partially embedded within sponges or coral structures, this species is frequently identified by its distinctive, bright yellow siphons that protrude from its otherwise translucent or brownish body.

Distribution & habitat

This species inhabits a variety of marine environments throughout the Indo-Pacific, ranging from Madagascar and the Great Barrier Reef to Indonesia, New Caledonia, and Micronesia. It typically favors calm lagoon waters over turbulent reef areas, residing in depths from the littoral zone down to over 100 meters. Individuals are often found tucked into rocky crevices or hidden within coral formations, such as brain corals.

Appearance

Typically measuring 5 to 10 cm in length, some individuals can reach up to 20 cm. The body is encased in a firm, gelatinous, and relatively thick tunic that is often covered in small bumps or irregularities. While the main body is often translucent or grayish-brown, it is frequently marked with sulfur-yellow spots or veins that become more concentrated around the siphons. The oral and atrial siphons are both crinkled, featuring approximately 15 to 20 lobes. Notably, its tunic possesses effective antifouling properties, keeping the surface free of other organisms.

Biology & behavior

As a solitary tunicate, this animal is sessile, typically attaching to the substrate by its left side or base. It is a hermaphroditic species that reproduces by releasing eggs and sperm into the water column. The resulting larvae are free-swimming and mobile before settling onto a suitable surface to undergo metamorphosis into their permanent, stationary adult form.