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Worms. 5 th Grade. 3 major Phyla. Flatworms Roundworms Segmented worms . Characteristics of ALL worms. Invertebrates Long, narrow bodies without legs Have head and tail ends. Do they have tissues , organs , and body systems ? .
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Worms 5th Grade
3 major Phyla • Flatworms • Roundworms • Segmented worms
Characteristics of ALL worms • Invertebrates • Long, narrow bodies without legs • Have head and tail ends
Do they have tissues, organs, and body systems? • Yes! Unlike sponges and cnidarians, worms DO have tissues and organs • Worms are the simplest organisms WITH A BRAIN
How does a worm’s brain and sense organs work? • Sense organs can detect objects, food, mates, and predators quickly • Sense organs that are sensitive to light, touch, and vibrations pick up information from the environment • Braininterprets that information and directs the animal’s response
Example: • A worm’s sense organ senses the vibrations of a footstep, and the brain tells the worm to quickly return to its underground burrow
Reproduction • Worms have asexual and sexual reproduction depending on the species • Some worms reproduce asexually by breaking into pieces. • If you cut some kinds of worms into several pieces, a whole new worm will grow from each piece
What kind of symmetry to worms have? • Bilateral Symmetry
1) Flatworms • Flat • soft like jelly • Ex. Tapeworms, Planarians, Flukes
Flatworms CAN be parasites • Parasite: an organism that lives inside or on another organism • Parasites take food from their host • Host: the organism that the parasite feeds on
Parasites: • Rob their hosts of food • Make the hosts weak • May injure the host’s tissues or organs • Rarely kill host • ALL flukes and tapeworms are parasites
Flukes • 10,000 species of flukes • Range from .2 inches to 4 inches
Tapeworms • Attack the intestines • Range from .04 inches to 50 ft
Planarians • Free-living flatworms • Free-living organism: does not live in or on other organisms • Glide over rocks in ponds, slide over damp soil, swim slowly through the ocean
Planarians are scavengers! • What is a scavenger?
Scavengers: organisms that feed on dead or decaying material • Planarians feed like a vacuum cleaner • Glide onto their food and insert a feeding tube into it • Digestive juices flow out of the planarian and into the food, breaking down the food while it is still outside of the body • Planarian sucks up the partly digested bits
Planarians are scavengers and predators Either feed on dead or decaying food Or Attack any animals smaller than they are
Planarians • Size: usually between 1/8 of an inch to 1 inch • Some tropical forms can be up to 2 ft!
Planarians • Have 2 dots that look like eyes • Eyespots: can detect light but cannot see a detailed image as human eyes can • Planarian head also has cells that pick up odors • Planarians rely mainly on smell, not light to locate food
Tapeworm Life Cycle • http://www.youtube.com/watch?v=EEBbtwGqPEs