Flatworm 6
Domain: EukaryaKingdom: Animalia
Subkingdom: Eumetazoa
Superphylum: Platyzoa
Family: Platyhelminthes
Genus:Turbellaria
Turbellaria are free-living flatworms most of which enhabit fresh water, saltwater or moist places on land.
Characteristics:
1. Symmetry bilateral. Three germ layers (triploblastic). Body usually flattened dorsoventrally. No true segmentation.
2. Epidermis soft and ciliated(turbelaria)
3. Digestive system incomplete (a mouth but no anus) and usually much branched. A flexible tubular proboscis traps prey such as small crustaceans and molluscs.
4. Muscle layers well developed. No body cavity. Spaces between internal organs filled by loose parenchyma.
5. No skeletal, ciculatory or respiratory systems. Excretory system with many flame cells connected to excretory ducts (protonephridia).
6. The nervous system is a pair of anterior ganglia or a nerve ring connected to 1 - 3 pairs of longitudinal nerve chords with transverse commissures.
7. The sexes are usually united (monoecious). Reproductive system of each sex with gonads, ducts, and accessory organs. Fertilization occurs internally. The eggs are microscopic, each enclosed with several yolk cells in a shell. Flatworms are hermafroditic, but cross fertilise. Partners then lay strings of large yolky eggs. The development in its life cycle is either direct (some Turbellaria and monogenetic Trematoda) or with one or more larval stages (digenetic Trematoda and some Turbellaria and Cestoda). Asexual in some species.
Worms found under a plank lying on the ground
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