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Planaria Lab

Planaria Lab. Examining a simple invertebrate. Classification :. Kingdom Animalia Phylum Platyhelminthes (flat worms) Characteristics of the flatworm phylum: Bilateral symmetry, cephalized Flat, thin, tapered body Made of epithelial, nerve, and muscle tissue, but have very few organs

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Planaria Lab

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  1. Planaria Lab Examining a simple invertebrate

  2. Classification: • Kingdom Animalia • Phylum Platyhelminthes (flat worms) • Characteristics of the flatworm phylum: • Bilateral symmetry, cephalized • Flat, thin, tapered body • Made of epithelial, nerve, and muscle tissue, but have very few organs • Most are internal parasites

  3. 3 Major Classes (within this phylum): • Class: Trematoda • Fluke worms • Parasitic • Liver • Blood

  4. 3 Major Classes (within this phylum): Class: Cestoda • Tapeworms • Intestinal parasites

  5. 3 Major Classes (within this phylum): • Class: Turbellaria • Planarians • Free-living, scavengers • Live in ponds, lakes, moist areas etc. • Harmless; part of the food chain • Hermaphrodites • No blood, few organs • Oxygen diffuses into cells directly from water

  6. The Planarian • Very simple flatworm • Soft-bodied, easily damaged, but… Their simplicity allows them to easily regenerate new parts!

  7. Movement • You will notice than the Planarian can twist, turn, and contract (shorten) its body = MUSCLES • You may also notice your worm “gliding” across the water. This is because they have CILIA on their ventral surface that “sweep” them along.

  8. The Planarian • Nervous system: • Photoreceptors: light-sensitive nerve cells • Chemoreceptors: chemical-sensitive nerve cells (taste and smell) • Mechanoreceptors: touch/pressure-sensitive nerve cells • Thermoreceptors: temperature-sensitive nerve cells

  9. The Planarian • Nervous System • Not very complex • Simple “brain” = GANGLIA • Operate on a basic “self-preservation” response to environmental stimulus • Eyespots • Ladder-shaped nervous system • Longitudinal nerves • Transverse nerves, latitudinal

  10. The Planarian • Digestive System • Single opening (mouth) • Pharynx: feeding tube • Three-part, branched intestine • Needed for nutrient distribution to all cells • Lack blood, no circulation

  11. Your Experiment: • Are they touch sensitive? Which parts (anterior or posterior) seem most sensitive? • Can they sense gravity (up/down)? • Do they sense light? If so, do they prefer dark/light? • Can they locate food? How? Are they hungry?

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