The saguaro (pronounced suh-wah-roh) cactus is found only in the Sonoran Desert areas of southern Arizona, northern Mexico, and a small area of southeast California. We call them saguaro desert old-timers for a good reason. Saguaros grow very slowly as a single stem for perhaps 75 years before developing arms. Plants with five arms may be 200 years old.
Saguaro flowers bloom at night from April to June. They close by noon the next day, never to open again. Saguaro flowers can only be fertilized by cross-pollination so there must be a creature to carry pollen from one plant to another. Because the flowers bloom at night, bats are the pollinators. They drink the nectar and transfer pollen from plant to plant.
A successfully pollinated flower will produce a green, oval-shaped fruit with bright red pulp. Many desert creatures eat the fruit and aid the saguaros by spreading their seeds. Only a small percentage of the seeds will ever germinate, but that’s okay because each flower produces as many as 4000 seeds.
Not only do the saguaros have a symbiotic relationship with the bats which consume their nectar and the many creatures who consume its fruit, but it also provides shelter for many desert animals. Saguaros become apartment houses for birds, lizards, desert rodents, and reptiles, as well as a whole entourage of insects.
Saguaros are remarkably well-designed for life in a dry climate. The outside of the plant has pleats like an accordion. The pleats allow expansion for storing large quantities of water when the rains come. As with other cacti, the saguaro has needles rather than leaves to reduce the loss of moisture by transpiration.
Those of us who live many miles from the ocean may not think about what goes on under the water. Similar to the land, there is an enormous diversity of plants in the sea. Just like land plants, ocean plants have flowers and pollinate and reproduce. Seagrass grows on the floor of the ocean and provides habitat for sea turtles, manatees, and many other marine animals. There are some 60 species of seagrass, and those grasses bloom and release pollen. Like land plants, seagrasses need something like the bees that help pollinate land plants. So are there underwater bees?
Researchers at the National Autonomous University of Mexico have reported that hundreds of crustaceans and other small insect-like animals visit plants and bring pollen with them. These invertebrates are the “underwater bees.” Along with ocean currents, they allow ocean vegetation to flourish.
As scientists study ways in which carbon can be locked up to avoid high concentrations in our atmosphere, they find that the ocean is a major factor in avoiding runaway greenhouse heating of the earth. Life in the oceans is essential to life on land.
Here is another design feature of this planet which is critical to the long-term existence of life on Earth. In the 1950s, scientists thought that there were maybe five or six factors which would be critical to the existence of life. The famous Drake Equation of how many planets could have life on them only considered five factors in its original format. Now we know there are a huge number of things that have to be “right” to allow life to exist.