TED-Ed: Nature's fortress: How cacti keep water in and predators out | Lucas C. Majure

Cacti are remarkable plants that have evolved to thrive in harsh desert climates. Their spines, which are modified leaves, help reduce water loss and regulate temperature. Cacti like the melon and saguaro have developed unique adaptations such as thick skins, waxy cuticles, and specialized root systems to store and conserve water. Even in rainforests, cacti like the mistletoe cactus use adaptations inherited from their desert ancestors to survive.

What is the primary function of cactus spines?

• To attract pollinators

• To store water

• To reduce water loss and regulate temperature

• To enhance photosynthesis

How do melon cacti minimize water loss?

• By having deep roots

• By opening stomata during the day

• By having a thick, waxy cuticle

• By growing in shaded areas

What adaptation allows the saguaro cactus to quickly absorb water?

• Deep tap roots

• Photosynthetic leaves

• Ephemeral rain roots

• Thick bark

Where can the mistletoe cactus survive despite limited water access?

• On tree branches in rainforests

• In marshlands

• On mountain tops

• In the desert

What substance in cactus cells helps retain water?

• Mucilage

• Chlorophyll

• Lignin

• Cellulose