Oyster flatworm

The oyster flatworm (Stylochus ellipticus) lives in tide pools and under rocks. This cream-colored organism has a narrow band of eyespots and a fringe of tiny tentacles on its anterior end. Oyster flatworms, which can grow up to 1 inch (2.5 cm) long, feed on barnacles as well as oysters. 

The speckled flatworm (Notoplana atomata) lacks tentacles but has eyespots arranged in four clusters. On the dorsal side, the worm is brown with small flecks of color. Like the oyster flatworm, the speckled flatworm is small, usually less than 1 inch (2.5 cm). 

Worms are plentiful in the shallow intertidal waters. Both simple flatworms and more complex segmented worms can be found there. Because of its size, the milky flatworm may be the most obvious, but the shoreline also supports many other types, including the speckled flatworm and oyster flatworm. 

Parasitic stages, on the other hand, generally do not use oxygen as the final electron acceptor but use fermentative processes to obtain most of their ATP. For these stages, an uneconomical energy metabolism is not detrimental, as the host provides the nutrients. Most adult flatworms inside the final host produce end products of a fermentative carbohydrate breakdown, such as succinate, acetate, propionate and lactate. These end products are formed via malate dismutation, a fermentative pathway, which is present in all types of parasitic worms (flatworms as well as many nematodes), but which is also present in animals like freshwater snails, mussels, oysters and other marine organisms. Malate dismutation is linked to a specially... 

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