1. Excretion in Lower Organisms

2. Aim: How does excretion occur in lower organisms?
I. Excretion in the Ameba/Paramecium
A. The ameba and paramecium get rid of NH3(nitrogenous waste) by diffusing it into their water environment through cell membrane.
1. Contractile vacuole – organelle that helps these organisms maintain proper water level within the cells. Active transport.
B. The A and P get rid of CO2 by diffusing it into water environment.

3. Contractile Vacuole

4. II. Excretion in the Hydra
A. CO2 and NH3 diffuses through cell membrane into water environment.

5. III. Excretion in the Earthworm
A. CO2 diffuses out of body through skin.
B. Nephridia – excretory organs that are in pairs in each body segment.
1. Carry nitrogenous wastes (urine) from the body to pores in body wall.

6. 2. Urine (Earthworm) – made up of urea, ammonia, water, and salt.
IV. Excretion in the Grasshopper
A. Spiracles – CO2 exits the body through these openings.
B. Malpighian tubules – Excretory organs located over the stomach and large intestine.

7. 1. Pick up nitrogenous wastes (uric acid), mineral salts, and water
1. Pick up nitrogenous wastes (uric acid), mineral salts, and water. Most of water is reabsorbed back into the blood.

8. 2. Uric acid – insoluble nitrogenous waste that is present in land animals that have a limited supply of water.
3. Uric acid and minerals are expelled with digestive wastes through the anus.