The Worms! Three Phyla of Worms • Flatworms – Phylum Platyhelminthes • Roundworms – Phylum Nematoda • Segmented worms – Phylum Annelida Worm Body Characteristics • Body Symmetry: bilateral • Cell Organization: cells to tissues to organs to SIMPLE organ systems • Reproduction: sexual/asexual (regeneration) • Body Development: zygote to egg to cocoon to adult The Flatworms • Over 10, 000 species • Flat bodies • Most are parasites – Tapeworms – Liver flukes • Non parasitic types – Planarian Tapeworms are Parasites • Can live in humans, dogs, cats, horses, pigs, and other pets. • Step 1: the larvae is ingested (ex. eating pork that was infested with the tapeworm eggs) • Step 2: Larvae grows into a worm and hooks onto the intestine wall • Step 3: Tapeworm feeds off of food in the intestines; grows larger and larger • Step 4: Eggs leave through the feces of the host and the eggs can be ingested by another animal. How Do You Get rid of a Tapeworm? • Medicines can kill the worm and the host gets rid of the worm in tiny pieces through its feces. • Worm can be “coaxed” out through the mouth or anus. • Worm can be pulled out through a small incision in the skin. The longest tapeworm ever removed from a human came out of Sally Mae Wallace on September 05, 1991. In all, doctors pulled 37 feet of tapeworm out of Sally Mae Wallace's body through her mouth. If you find all of this disgusting, be glad you're not a whale as tapeworms in whales can grow up to 120 feet long. The Roundworms • Cylindrical bodies • One-way digestive system • Some are parasites Tubeworms grow on ocean thermal vents. They grow from both ends! Raccoon roundworms Ascaris roundworm Found only in humans where there are unsanitary conditions and poor plumbing. Roughly 1 in 6 people worldwide are infected. Eggs hatch and bore through intestine walls. The worm then moves to the heart, the lungs and then OUT the breathing passages. The Segmented Worms • Bodies are long and narrow • Made up of many linked sections called segments. • Exs. – leeches, earthworms, bristle worm Earthworms help to aerate soil and increase plant growth. Leeches can be used for medicinal purposes The Segments • Many organ systems run through all the segments – Digestive system, nervous system, circulatory system • Others are found only in certain areas – Reproductive system How Do Some Worms Reproduce? • Asexual Reproduction – Regeneration: the regrowth of an organ, tissue, or part that has been lost or destroyed Sexual Reproduction In Earthworms HOW EARTHWORMS LIVE • They tunnel for a living • They are scavengers – Eat the decayed remains of plants and animals • Earthworms come out mostly at Who am I? I am a giant night. earthworm Where do I live? I burrow – The ground is damp deep into the wet earth of the rainforest – Most predators are asleep What do I eat? Leaf litter and • Worms get their oxygen through their dirt What do I do? I grow up to a damp skin. meter long and I am bright blue – If they dry out they will die What is special about me? My spit glows in the dark How Do Earthworms Move? • The worms have welldeveloped muscles that allow them to burrow • Bristles (setae) are found on each segment and stick into the ground. How Are Earthworms Beneficial? • Improve the soil in which plants grow. • Earthworm droppings make the soil more fertile. • Earthworm tunnels loosen the soil and allow air, water and plant roots to move through it. • Earthworms are decomposers and can be used in compost piles.
