1. STATION ONE: Study this picture of the environment of Galapagos Opuntias (prickly pears). List at least 3 challenges the cacti would face living in this environment.

2. STATION TWO: Cacti are plants (Kingdom Plantae). They have the same structures as all other plants, but the structures have been modified. In this lab, you will see modifications of the stem, leaf and tissues in Cacti. A TYPICAL PLANT

3. Label your sketch using the drawing above. Make a sketch of the piece of Opuntia cactus at this station (cactus or photo).

5. STATION THREE (1): STEMS The CLADODES (or pads) of Opuntia look like leaves but they are actually modified stems. This is known from the way they grow and from the tissues that carry water and carry out photosynthesize inside them. The trunk and leave-like pads are considered homologous structures to the stem of a typical plant.

6. STATION THREE (3): Stems of Opuntia are green. They have tiny openings called stomates that let in carbon dioxide needed for photosynthesis. These are usually found on leaves. Modifications to Cactus Leaves During the evolution of cacti, the genes for making stomates became active in stems, when they are usually only active in leaves. This is an example of a homeotic mutation that was beneficial. stomates

7. STATION THREE (2): Stems The cactus pads are round and fleshy so they have less surface area - this reduces water loss. They also have a waxy covering called the cuticle. http://www.sbs.utexas.edu/mauseth/researchoncacti/cortex%20text.htm How do the rounded shape of the cactus pads and the waxy cuticle help the cactus survive?

8. STATION FOUR (1): LEAVES The leaves of cacti are the spines. They contain all the tissues normally found in green leaves. Leaves have been modified for different uses in cacti such as defense against herbivores and protection from the sun., The tiny hairs are called glochids.

9. How do the spines and glochids help the cactus survive in its environment? STATION FOUR (3): The trunks of tree cacti are covered with spines.

10. STATION FIVE: REPRODUCTION Opuntia reproduce both sexually and asexually. Sexual Reproduction: How do offspring produced by sexual reproduction compare genetically to the parent plants? How could this help the parent (and species) survive genetically?

11. STATION FIVE (2): POLLINATORS Cacti depend on pollinators to move pollen from one plant to another to increase genetic variation in their populations. Flashy flowers and nectar attract pollinators.

12. STATION FIVE (3): ASEXUAL REPRODUCTION Opuntia can reproduce asexually from fruits or pads that fall from the parent plant. treeandplantnursery.com watchingtheworldwakeup.blogspot.com New plants can sprout from nodes called aureoles. How do asexual offspring compare genetically to the parent plant? How could asexual reproduction help the parent plant survive?

13. STATION SIX: PHOTOSYNTHESIS Cacti save water through a special form of photosynthesis called CAM: Plants need carbon dioxide from the air - but they can dry out getting it!

14. Cacti take in carbon dioxide at night, when evaporation is less, and store it in a C 4 molecule to use during the day. How does CAM photosynthesis help the cactus survive and reproduce in its environment? STATION SIX (2):

15. STATION SEVEN (1): GROWTH FORM Growth form refers to the shape of the plant. Tree cacti have a tree-like or arborescent growth form. Some Opuntia in the Galapagos have a bush-like form called decumbant or prostrate. DECUMBENT ARBORESCENT

16. Frank J.Sulloway http://www.skeptic.com/eskeptic/06-07-28/ How is the arborescent growth form an adaptation to their environment?

17. STATION SEVEN(3): Giant tortoises like to eat cladodes that fall from tree cactus. They will eat the low-hanging cladodes of the cacti. Which islands have tree cacti on them? How is the arborescent growth form an adaptation to their environment?

18. + + X STATION SEVEN (4)

19. STATION EIGHT: HUMAN USES OF OPUNTIA Which of these are actually uses for prickly pear cacti?  Fruit  Vegetable  Source of dye for food  Diabetes treatment  Decorative Garden Plant  Clothing  Anti-erosion  Making bricks  Vitamins  Alcoholic beverage

20. STATION EIGHT(2): HUMAN USES OF OPUNTIA ANSWERS:  Fruit  Vegetable  Source of dye for food  Medicines  Decorative Garden Plant  Toothpaste  Clothing ?????  Anti-erosion  Making bricks  Vitamins  Alcoholic beverage

21. STATION EIGHT(3): Beetles grown on prickly pear make an organic red food dye. Mmmmmm!

22. STATION EIGHT (4): Can these human uses of Opuntia be considered an adaptation of Opuntia?? Why not? Used to help stop desertification and provide food for animals. http://www.fao.org/DOCREP/005/Y2808E/y2808e0d.htm

23. In the Galapagos, Opuntia species are affected by human impacts: Habitat loss  Farms displace natural communities. Invasive species  Goats, donkeys, pigs, horses all eat Opuntia. Climate change  El Nino rains and storms can knock over tree cacti CONSERVATION STATION NINE: CONSERVATION

24. STATION NINE (2):

25. Climate Change More frequent EL NIÑOS Sea level rise Increased rainfall Cacti live near the ocean. Their habitat will be reduced by sea level rise. Cacti swell with water when it rains and can topple over. High winds can knock large cacti over. STATION NINE (3):

26. STATION 8: CONSERVATION Critically Endangered means that a species' numbers have decreased, or will decrease, by 80% within three generations. Vulnerability is mainly Caused by habitat loss or destruction. An endangered species is a population of organisms which is at risk of becoming extinctextinct. STATION NINE (4):

27. SPECIES Genus species IUCN STATUS Opuntia helleri VULNERABLE Opuntia galapageia ENDANGERED Opuntia insularis ENDANGERED Opuntia megasperma VULNERABLE Opuntia saxicola CRITICALLY ENDANGERED Opuntia echios VULNERABLE STATION 9 (last!): CONSERVATION The six species of prickly pear cacti in the Galapagos are threatened by habitat loss, invasive plants and animals. What are the threats to survival of Galapagos Opuntia species? What is a good reason to conserve these species?

28. Exit slip: Describe an adaptation of Opuntia. Give the specific environmental challenge it helps the plant cope with and tell why it is an adaptation.