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

• Brain interprets 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

Fluke

Flukes

• 10,000 species of flukes

• Range from .2 inches to 4 inches

Tapeworm

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

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

Planarians

Tapeworm Life Cycle

• http://www.youtube.com/watch?v=EEBbtwGqPEs