12c

There are two equal sides to an animal and one mirrors the other side.

Is a free living flatworm in freshwater. NOT saltwater.

Is when an animal lives inside of another host. Parasite flatworms get nourishment from host. Can eventually kill host.

Worms nervous system. They have nerve tissue throughout body. Sometimes is called simple brain. Many invertebrates have several of them.

Something causes a reaction in an organism. Whatever receives it turns it into impulse. Travels to ganglion. Sends to structures for response.

Planarians have these. Make it look cross eyed. Sensitive to light. Light is negative.

Part of digestive system. Eat by extending muscular tube through mouth. Enzymes digest food.

When an animal has both male and female reproducing parts.

When planarian is cut in half and regrows other cut off half.

Have a round tubular body, tapered at each end. Can be serious parasites. Some are free living.

Roundworm that is a parasite. Lives in animal intestines. As long as 12 inches.