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Ecological Relationships: Symbiosis. There are three main types of symbiosis, based upon the specific relationship between the species involved: mutualism , mutual benefit to the interdependent organisms
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Ecological Relationships: Symbiosis • There are three main types of symbiosis, based upon the specific relationship between the species involved: • mutualism, mutual benefit to the interdependent organisms • parasitism, one organism receives no benefits and is often injured while supplying nutrients or shelter for the other organism • commensalism, association between two different kinds of creatures, called commensals, that is harmless to both and benefits at least one.
Commensalism Small birds like this sparrow (left) make their homes beneath the nests of a large, fish-eating osprey. The presence of the fierce osprey provides protection for the little birds.
Mutualism: Ratel and the Honey Guide In Africa, the honey guide bird lives in a mutualistic relationship with a furry animal called a ratel. The bird loves to eat beeswax, but is too small to break into a bee’s nest easily. The ratel likes honey but cannot always find a supply on its own. The honey guide locates a bee’s nest and chirps loudly for the ratel. With its sharp claws, the ratel rips the nest open and shares a feast with the honey bird.
Mutualism • The white ibis is a fish eating bird. • Poisonous snakes live at the base of the tree in which this bird makes its nest. • The snakes catch pieces of fish that the birds drop. • The snakes keep raccoons and other animals away from the ibis’s eggs and baby chicks.
Mutualism: Tickbirds The relationship between these water buffaloes and tickbirds is an example of mutualism. The tickbirds feed on tiny insects they pluck from the hide of the buffalo. The buffalo protect the birds and are freed from their parasites.
Mutualism: Oxpeckers and Egrets • African oxpeckers spend most of their time on the bodies of cattle and of the rhinoceros, eating the ticks and other insects in the hide of the animal. The animal provides the bird with its food supply. In return, the bird not only keeps the animal free of parasites, but warns it of danger from other animals. • Egrets feed on insects kicked up by the feet of grazing rhinoceroses and cattle.
Mutualism: Lichens • An example of mutualism is the coexistence of certain species of algae and fungi that together compose lichens. • Their close association enables them to live in extreme environments, nourished only by light, air, and minerals. • Living separately, the alga and fungus would not survive in such conditions.
Mutualism: Ants and Aphids • Honeypot ants tend their aphids and periodically "milk" them for their honeydew secretions by stroking the aphids gently with their antennae. Ants will aggressively protect their aphids and may even move them when they are in danger, transferring them into temporary shelters or new nests. • This type of behavior demonstrates a kind of • symbiosis called mutualism, in which both creatures benefit • from the association.
Parasitism: Dodder Plant The dodder plant lives by obtaining all its food from host plants, such as clover and alfalfa. Wrapping its stem around the host plant, the dodder pushes its sucker into its host. Then it releases itself completely from the soil and stays attached to the host plant for support and food.
Parasitism: Blood Flukes • Flukes of the genus Schistosoma parasitize two hosts. The young hatch from their eggs in rivers and lakes and enter a specific kind of aquatic snail, where they develop into tadpolelike larva called cercariae. When the cercariae leave the snail, they burrow through the skin of a human host swimming or wading in infested water. Adult flukes mature in the host’s bloodstream and settle in the • veins of the gut. Their eggs, deposited in the lining of the • human intestine and bladder, pass back into water via the • sewage system, and the cycle begins again.
Parasitism: Tapeworms • Tapeworms are parasitic worms that infest the intestinal lining and other organs of vertebrates. • Tapeworms, having no mouth or digestive tract, are able to absorb partially digested material through their body surface.
Parasitism: Ticks • Ticks are members of the class Arachnida, which includes spiders, scorpions, daddy longlegs, and mites. All ticks are carnivorous, feeding on the blood of various species of birds, reptiles, and mammals, including human beings. Ticks use their mouthparts to anchor themselves to the skin, where they cut a small hole and suck the blood. A number of tick species transmit diseases infecting livestock, pets, and humans.
Parasitism: Beneficial Wasps • Ichneumon wasps parasitize other insects by laying eggs in their host’s larvae. The developing young wasps devour the larvae as they grow, often eliminating pests harmful to humans. The female of this species drills through bark with her long egg-laying structure, called an ovipositor, to deposit an egg on the larva of the giant wood wasp, Uocerus gigus.
Parasitism: Mistletoe • Mistletoe is a widespread flowering plant parasite that grows on oak, apple, juniper, pine, and other trees. Most mistletoe species are actually hemiparasites, or partial parasites.Their leaves, found on the surface of branches and trunks, produce sugar through photosynthesis, but their roots penetrate into the tree’s tissue and absorb its nutrients. Some species of mistletoe lack leaves altogether and rely solely on their host tree to provide all their nourishment.
Parasitism: Corn Smut • The corn smut is a parasitic fungus that attacks the ears, stalks, and tassels of corn. Large, unsightly mycelial, or fungal, masses develop that eventually produce large quantities of black spores. Occasionally smut galls or swellings are produced, which are used as food in some areas of Central and South America.
