Generally, flatworms have a characteristic in common with the cnidarians-the presence of a single opening into the body's cavity. This opening both ingests food and egests indigestible material. Flatworms exhibit bilateral symmetry, that is, the left and the right sides of the body are mirror images of one another. The turbellarian flatworms are mostly small bottom dwellers living in the sand or mud, under stones and shells, or on seaweed. They ordinarily have eyes on their tentacles or on the anterior edges of the body. The most conspicuous group on Philippine reefs (the Order Polycladida)) are larger than other flatworms, being 2cm or more in length, and are often brightly colored. Most larger polyclads have two groups of eyespots made up of many minute pigment spots at the anterior end. Some are free swimming and display a distinctive, graceful, undulating motion. found almost entirely in the rocky regions of the littoral zones. Have practically no enemies but are limited by their specialized requirements for a protected area away from surf or moving rocks. Polyclad flatworms get their name from having "many" branches to their gut. Many of the flamboyantly colored species are believed to display aposematic or warning coloration.
Acoel flatworms are very small, and are found on numerous substrates. Some species have eyes or anterior sensory areas, and all have a sensory ganglion. Most species are thought to graze on the surface flora and fauna trapped in the mucus of the host. Gut analysis suggest that their diet consists of tiny crustaceans, mainly copepods, plus detritus and diatoms. Taxonomy is largely based upon characteristics of the reproductive organs.
Phylum Platyhelminthes (Flatworms, Polyclad worms) (Philippine Translation: Uod)
Order Polycladidia (Common Marine Flatworms, Polyclad Worms)
Acanthozoon Sp. Length to 100mm. Avery common, yet undescribed species. This cryptic species is found under boulders and rubble. (1)
Pseudoceros Sp. No info was found on this one but should you know...please let us know. (1) (2) (3)
Order Arcoela (Small Marine Flatworms)
Waminoa Sp. This species of acoel is a flat disc in the shape of a pumpkin silhouette. The olive green color may be due to an algal or diatom symbiont, which is unknown. There is a yellow spot at the base of the caudal notch. Found on the bubble coral Plerogyra sinuosa, giving it the appearance of green spots. (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.