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KEY CONCEPT Flatworms , mollusks , and annelids belong to closely related phyla. Flatworms. Flatworms are simple bilateral animals. Flatworms have a solid body and incomplete or absent gut . There are three classes of flatworms. 1. Planarians.
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KEY CONCEPTFlatworms, mollusks, and annelids belong to closely related phyla.
Flatworms are simplebilateral animals. • Flatworms have a solidbody and incomplete or absentgut. • There are threeclasses of flatworms. 1. Planarians • Can re-build any part of their bodies after amputation • Can be parasitic (rare) towards corals, eggs, or other stationary “victims”
Flatworms are simple bilateral animals. • 2. Flukes • Parasitize fish, frogs, and turtles, humans, domestic animals, and invertebrates. • People can become infected by consuming uncooked fish, plants or animals from waters that are fluke-infested. • Symptoms: fever, rash, diarrhea, rash
Flatworms are simple bilateral animals. 3. Tapeworms • Parasitize cows, pigs, and humans • Infection is caused by ingesting food or water contaminated with tapeworm eggs or larvae. • Symptoms: nausea, weakness, loss of appetite, abdominal pain, weight loss, diarrhea
Mollusks and other bilateral animals have a completedigestivetract. A complete digestive tract has twoopenings: a mouth and an anus. Mollusks are diverse animals.
heart intestine mantle cavity mantle stomach digestive gland radula foot salivary gland mouth anus crop • Radula (for feeding, sometimes compared to a tongue) • Mantle (dorsal body wall which covers the organs of digestion, reproduction and movement- - - the epidermis of it secretes CaCO3 to make a shell) • Ctenidia(modified gill) • Mollusks share at least one of threefeatures.
Gastropods (Snails and Slugs) • Pelecypods (also called bivalves) (Clams) • Cephalopods (Squids, Octopuses and Cuttlefish) • Most mollusks are classified into three (of seven) classes.
Mollusks have a variety of reproductive strategies. • Most strategies involve sexual reproduction. • Some species are hermaphrodites.
brain blood vessels hearts muscle mouth digestive tract segment nerve cord Annelids have segmented bodies. • Segmentation refers to the repeatedsections of an annelid’s body. • The coelom is a fluid-filledspace completely surrounded by muscle.
There are threegroups of annelids. • Earthworms • Marine worms • Leeches