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Phylum Platyhelminthes - flatworms

Unsegmented worms with thin flat bodies.  Majority of species are parasitic (flukes and tapeworms).  Most  free-living flatworms are small and inconspicuous, but a few local species are larger, often with striking markings.   Flatworms glide about using mucus & cilia as well as muscular undulations of their bodies.  Most are predators of small invertebrates; their gut has but a single opening.   Despite the general simplicity of their body structure, flatworms possess complex hermaphroditic reproductive systems.  ~20,000 species.

Eurylepta californicaEurylepta californica  Hyman, 1959

Phylum Platyhelminthes, Class Rhabditophora, Order Polycladida, Family Euryleptidae

Oval worm with flared tentacles bearing black & red marks at their base; length to 30 mm. Body grayish white with narrow mid-doral white line and scattered crisscrossing pattern of dark lines with scattered white spots.

Uncommon and cryptic, under cobbles and amongst low-lying red algae. Little is known about this species; congeners reported to feed on ascidians.

Geogr. Range: central California
Similar species: Pseudoceros montereyensis has black spots rather than crisscrossing lines and a black line around its lateral margin.



Pseudoceros montereyensisPseudoceros montereyensis  Hyman, 1953

Phylum Platyhelminthes, Class Rhabditophora, Order Polycladida, Family Pseudocerotidae

Large oval worm with ruffled margin; 40 mm long. White with mid-dorsal black line tinged with red; continuous black line around margin except between anterior tentacles; dorsum speckled with elongate black marks and fewer white spots & red flecks.

Uncommon and cryptic, under cobbles and amongst low-lying algae. Little is known of its biology, although congeners are reported to prey on compound tunicates.

Geogr. Range: central California; also reported from Oregon as well as southern Calif.
Similar species: Eurylepta californica has criscossing black lines instead of spots & lacks black line around lateral edge of body.