Bestiality

Sea anemones are animate chrysanthemums made of tentacles. Without sense organs, without a nervous system, they are all skin, with but one orifice that serves as mouth, anus, and vagina. Inside, their skin contains little marshes of algae, ocean plantlets of a species that has come to live only in them. The tentacles of the anemone bring inside the orifice bits of floating nourishment, but the anemone cannot absorb them until they are first broken down by its inner algae garden. When did those algae cease to live in the open ocean and come to live inside sea anemones?

Hermit crabs do not secrete their own shells, but instead lodge their bodies in the shells they find vacated by the death of other crustaceans. The shells of one species of hermit crabs are covered with a species of sea anemone. The tentacles of the sea anemones grab the scraps the crab tears off when it eats. Since sea anemones have stings on their tentacles, the crab is protected from predator octopods, which are very sensitive to sea anemone stings. When the hermit crab outgrows its shell, it locates another empty one. The sea anemones then leave the old shell and go to attach themselves onto the new one, as the crab waits. How do sea anemones, blind, without sense organs, know it is time to move?

Small nomadic bands of people have long lived in the rain forests of the world. But until recently only two commercial ways were found for humans to live off the rain forest without destroying it—tapping rubber trees and collecting Brazil nuts. Rubber has many essential uses in industry, and Brazil nuts have always commanded good prices on the export market. But there are so many species of trees intermixed in the rain forest that rubber tappers and nut collectors often had to walk for an hour from one tree of a species to the next. It early occurred to settlers to cut down the wild forest, and plant plantations of rubber trees and Brazil nut trees. The Brazil nut plantations always failed. The trees grew vigorously, flowered, but never produced any nuts. Only fifteen years ago did biologists discover why. The Brazil nut flowers can be pollinated by only one species of bee. This bee also requires, for its larvae, the pollen of one species of orchid, an orchid that does not grow on Brazil nut trees. When did Brazil nut flowers come to shape themselves so as to admit only that one species of bee? What we know as Brazil nuts are kernels which, on the tree, are enclosed in a very large wooden husk containing hundreds of them. The Brazil nut tree is hardwood, and the husk about its seeds is of wood hard as iron. There is only one beast in Amazonia that has the teeth, and the will, to bore into that husk. It is a medium-sized rodent, and when it bores through the husk, it only eats some of the seeds. The remaining seeds are able to get moisture, and push their roots into the ground. Without that rodent, the nuts would be permanently entombed, and Brazil nut trees would have died out long ago.

There is perhaps no species of life that does not live in symbiosis with another species. When did celled life, with nuclei, come to evolve? Microbiologist Lynn Margulis established that chloroplasts and mitochondria, the oxygen-processing cellular energy-producers in plants and animals, were originally independent cyanobacteria that came to live inside the cells of plants and animals. Colonies of microbes evolved separately, and then formed the symbiotic systems which are the individual cells, whether of algae or of our bodies.

Human animals live in symbiosis with thousands of species of anaerobic bacteria, 600 species in our mouths which neutralize the toxins all plants produce to ward off their enemies, 400 species in our intestines, without which we could not digest and absorb the food we ingest. Some synthesize vitamins, others produce polysaccharides or sugars our bodies need. The number of microbes that colonize our bodies exceeds the number of cells in our bodies by...