Lesson Goals: Students will describe differences and similarities in how organisms are adapted to survive

Transcription

1 Lesson Title: Body Systems of a tick Lesson Abstract: Students will compare body systems of a tick and human. Length of lesson: min Lesson Goals: Students will describe differences and similarities in how organisms are adapted to survive Lesson Objectives: SWBAT compare and contrast organ systems of ticks and humans Assessment of Objectives: Students will complete packet Preparation: Copies of packet Materials: none Background Information: Ticks represent an animal that is very different from a human. Yet they also must adapt to carry out the basic life functions. Lesson Plan: Intro What must all living things do to survive? Do all living things do these things in the same way? Today we will compare how ticks and humans carry out some of these basic life functions. Group Work (Alternative) QA Closure In groups of 2, students complete the packets. Groups of students could each be assigned one system. Then groups could split up in Jigsaw fashion and teach each other about the system they reviewed. When groups are done review packet questions. 1. Discuss the idea of adaptation. 2. Discuss what students found most interesting.

2 Tick References Tick illustration before and after blood meal Animation Removing Tick life cycle.html

3 lifecycle.jpg

4 The Tick A look at the body systems and structures What are ticks? Ticks are small animals. Ticks range in size from smaller than a sesame seed to the size of a pea. Many ticks are parasites. (Parasites obtain their food by living off of other living things) Ticks Humans Kingdom Animal Animal Phylum Arthropod exoskeleton, jointed legs Chordata have back supporting structure Class Arachnids have 8 legs Mammals have two pairs of limbs, hair 1. Respiration Arachnids may have book lungs or tracheal tubes. Book Lungs contain plates (pages) that contain tiny blood vessels. Air enters the through slits in the abdomen and pass over the plates. Carbon dioxide and Oxygen are exchanged.

5 Tracheal tubes are microscopic air ducts that branch throughout the Arachnids body. Other arthropods have tracheal tubes. Notice how they line the body and bring gasses in and out through tiny tubes. 2. Circulation Ticks have a simple heart and an open circulatory system. In an open circulatory system the blood does not stay in tubes. The blood pours over the organs and then is recollected. Grasshoppers also have an open circulatory system. Blood flows out into the open organ area and then back into the heart. 3. Nervous System The tick has a ventral nerve cord. (Ventral means in the front) Ticks have two feelers to help them find a host. They also have chemical receptors on their legs to sense a host.

6 Bees also have ventral nerve cords. In this diagram the nerve cord is labeled G 4. Locomotion Ticks have 8 jointed legs. Ticks have an exoskeleton and therefore need many joints to move. At the end of each leg ticks have sticky pads and a claw to help it cling to its host. This diagram of a grasshopper leg has each segment of the leg labeled. The exoskeleton of this insect is shown in brown. In order to grow the insect must molt. When it molts it comes out of its old exoskeleton. 5. Digestion Ticks have no jaws. Ticks feed by sucking the blood of their host. Their mouth is long and slim and covered with barbs, like a fish hook. The mouth drills a hole into the host and then it sucks up blood.

7 6. Reproduction Deer Ticks live up to two years. Their life cycle has four stages: Egg hatch in about 1month Larva have 6 legs, usually feed on mice. After feeding it drops off and hides until the next spring Nymph After feeding (May June) it drops off and becomes an adult Adults Adults can reproduce. The male dies after mating. The female must feed and then lives through the winter. In the spring it may lay up to 2500 eggs.

8 The Tick A look at the body systems and structures Review Questions: 1. Respiration How are our lungs like the book lungs of an arachnid? How are our lungs different? 2. Circulatory System How is our circulatory system different from that of a tick? Why does our circulatory system work better? 3. Nervous System How does the location of the nervous system differ between ticks and humans? 4. Locomotion What are the advantages of having an exoskeleton? What are the disadvantages of having an exoskeleton? 5. Digestion

9 Why would blood be such a good type of food? 6. Reproduction Diagram A Diagram B Both diagrams show the life cycle of a deer tick. Which diagram is easier to understand? Why?

10 What is the advantage of having multiple hosts? 7. Conclusion If you could piece together an organism with systems from both the tick and the human in order to make the most efficient organism what would you choose? Explain your answer. Why don t all organisms have the same body systems? Be specific, and give one example to support your idea.

11 Created in collaboration with Mrs. Jessica Hannah, Farnsworth Middle School, Grade 7