The plant suffers wasted energy and nutrients that go into the extra growth. A wasp, for instance, causes a plant to produce a gall in order to create a source of food and shelter in which its larvae can develop. There are many gall-inducing parasites: fungi and gall wasps are among the more common ones. These abnormal growths are a response to certain parasites invading the plant’s tissues. Galls on a plant are a sign that a parasite has been at work. Parasitic plants can increase the diversity of plant species in an area by keeping more dominant species in check. Common cow-wheat ( Melampyrum pratense) is semi-parasitic on the roots of a number of plants including blaeberry ( Vaccinium myrtillus), while lousewort ( Pedicularis sylvatica) and yellow rattle ( Rhinanthus minor) are found on grasses. Parasitic PlantsĮven some plants have a darker, parasitic side. But these fungi indirectly benefit other species by creating the dead wood habitat required by rare invertebrates such as the aspen hoverfly. Unlike most parasites, a lot of the bracket fungi kill their host tree. A good example is the aspen bracket fungus. Some of the more obvious ones are those found in trees, and form a variety of ‘bracket’ fungal bodies. Fungiįungi are virtually everywhere, and many species are parasitic. The Caledonian Forest is literally crawling with parasites – some of which are invisible, while others may be easily seen – or felt! There are some fascinating examples of more well-studied species that can help us glimpse their role in our native forest ecosystems. As we will see below, taking essential nutrients from another organism can cause it to weaken and affect its fertility, but the wider consequences of this are sometimes unexpected. They have a huge effect on living things and their populations, and are a major cause of disease in humans and other organisms. Parasites come in many shapes and sizes, and include viruses and bacteria, various worms, plants, fungi, insects, and even birds and mammals. More than half of the Earth’s species are parasites while virtually every species may play the host. Its feeding habits are known as parasitism. Now enter the bizarre world of parasitism.Ī parasite is a living thing that gets food from another organism, harming, but not killing it. An example would be mosses living on the bark of a tree. Commensalism is when one organism ‘hitches a ride’ on another, or uses it as a home, but causes no obvious harm. (Slightly confusingly, we commonly use the word ‘symbiotic’ to mean just ‘mutualistic’). Mutualistic relationships are a partnership: each of the life-forms involved benefits the other in a ‘win-win’ situation. Then there are the different kinds of symbiotic relationship which involve more close and complex interactions. Some feeding strategies are more familiar: carnivores are animals (and plants) that eat other animals, while herbivores feed on plants. Millions of years of evolution have resulted in a myriad of strategies for obtaining food, and these different interactions are part of the glue that binds ecosystems together. Food, in whatever form, is essential for the survival of living things.