its because the needles are actually leaves. they are small because if they were bigger, then they would waste water. also, the "leaves" have small waxy cuticles(i think that's how to spell them) that trap water and store it in the cacti's trunk.
To protect it for animals. They contain allot of water so their good food if your in the desert. They are leaves and so small because if they weren't they would wast water. they contain water.
Alli G rocks
Cacti have needles instead of leaves because it prevents water from being evaporated so they can survive in dry weather. Also, needles prevent animals from eating them.
if animals try to eat it the spiks protect it.
it reduces transpiration of water
The cactus is one of the few plants found in the desert, and in order to survive it needs a massive amount of water. Since it does not rain all year round in a desert, cacti store water when it does rain. So the needles on the cactus protect their water-rich flesh from other things in the desert.
The desert cactus
The desert cactus
It can store water inside itself. Also, its thorns prevent most predators from trying to eat or destroy it. Lastly, the cactus plant also has roots that go extremely deep into the dry desert ground, and it can find much water while other shallow-rooted plants are thirsty and wilting.
The jumping cholla [Cylindropuntia bigelovii] doesn't need to launch its thorns. The thorns just loosen easily in response to strong wind events, or contact. The cactus is native to North America. In Mexico, it's found in the Sonoran Desert. In the U.S., it's found in Arizona, California, and Texas. It's also known by a number of common names, including the ironic Teddy Bear cholla.
The cactus is one of the few plants found in the desert, and in order to survive it needs a massive amount of water. Since it does not rain all year round in a desert, cacti store water when it does rain. So the needles on the cactus protect their water-rich flesh from other things in the desert.
The desert cactus
The desert cactus
Cactus remain in the desert because they can survive in harsh environments. Cactus plants have the ability to collect all the water they can get, and store it inside them for months on end. The "thorns" or "pricks" of the cactus, protect the plant from animals who might want to eat it.Cactus is formed in the desert due to scarecity of water, high temperature and less organic matter in the soil.
Pioneers of northern Mexico and of the southwestern United States of America tried to ease cactus thorns out or remove them by force. They applied poultices to encourage the thorns to work their way out of the skin. Or they soaked the affected parts, for the same reason. Or they tried to remove them with heated, sterilized needles.
It can store water inside itself. Also, its thorns prevent most predators from trying to eat or destroy it. Lastly, the cactus plant also has roots that go extremely deep into the dry desert ground, and it can find much water while other shallow-rooted plants are thirsty and wilting.
cactus thorns are made up of Leaves
cactus
The jumping cholla [Cylindropuntia bigelovii] doesn't need to launch its thorns. The thorns just loosen easily in response to strong wind events, or contact. The cactus is native to North America. In Mexico, it's found in the Sonoran Desert. In the U.S., it's found in Arizona, California, and Texas. It's also known by a number of common names, including the ironic Teddy Bear cholla.
The horticulture students were amazed at the variety of cacti present in the Arizona desert.
The barrel cactus survive long periods of drought by storing sparse rain water in stem cells. Other species of cacti also store water. Leaves have evolved into thin spikes and thorns to reduce water loss, which would occur with conventual broad-leaves.
defence. the cacti leaves are the thorns...