Both solitary and encrusting colonial forms are common coral reef fauna. Tunicates derive their name from the tubular test, resembling a tunic, which enclose their bodies. The flexible body framework is composed of a cellulose like substance called tunicin. Tunicates are bag shaped, jelly like, upright animals that are always sedentary and live either singly or in colonies on most coral reefs. They are distinguished by opening or siphons, for the intake and outlet of water. Simple or single tunicates are called sea squirts because they squirt water from one or both of their opening when touched or squeezed. Often brightly colored, they attach to a firm substrate of rock, coral, mud or sand. On large ascidian (Didemnum) commonly seen on Philippine reefs is a single animal up to 10 cm high.
Phylum Chordata
Subphylum Urochordata
Class Ascidiacea (Sessile Tunicates, Ascidians, Sea Squirts)
Uncategorized: (1) (2) (3) (4) (5)
Clavelina Moluccensis Sp. (Bluebell Sea Squirt) This translucent sea squirt has colored markings near the siphons of each zooid and the branchial baskets are visible internally. (1)
Clavelina Robusta Sp. Often occurs in dense clusters of cylindrical zooids. It is distinguished by the dark blue to smoke gray or black body with lemon yellow, green, or white rings around both siphons. Probably one of the most commonly encountered tunicates. (1) (2)
Oxycorynia Fascicularis Sp. (Sea Squirt) Appear as clusters of grapes at the end of long stalks. The zooids are tightly congested in the head. Each zooid has its own pair of siphons. The colonies often form clusters and are mostly gray to dark green in color. Some other authors place this species in the genus Nephtheis. Commonly encountered around overhangs, slopes, and walls. Fed upon by Nembrotha Lineolata and Nembrotha Sp. (1) (2) (3)
Eudistoma Gilboviride Sp. Firm, globular or ball like colonies formed by wedge shaped lobes. Color is bright green to very dark green, mottled with pale yellow blotches. Locally common, mostly on shallow reef flats. (1)
Polycarpa Aurata Sp. (Goldmouth Sea Squirt) These are large bulbous solitary tunicates, commonly 4-10 cm in length, mottled with purple, white, and gold. The insides of the siphons are conspicuously yellow. The tunic is clean, without encrusting epizoic organisms. This species, along with Didemnum Molle, are probably the two most common sea squirts encountered in the western Pacific. Depth 3-20m. Attaches to rocky surfaces or exposed dead corals. (1) (2) (3) (4) (5)
Rhopalea Sp. (Transparent Sea Squirt) Variably colored from colorless to transparent sky blue, or opaque blue to purple. In transparent forms, the sperm duct often appears as a white, brown, or blue longitudinal line running throughout most of the length of the tunicate body. Very common throughout much of the Indo Pacific on reef flats and slopes. One form is fed upon by nudibranchs of the genus Nembrotha. (1)
*Reference: Philippine Coral Reefs A Natural History Guide By Alan T. White & Coral Reef Animals Of The Indo-Pacific By Terrence M. Gosliner, David W. Beherens, Garry C. Williams
*Photos: Are Full Moon Divers. All Rights Reserved.