what is a close and permanent relationship between 2 different organisms ?

A close and permanent relationship between two different organisms is known as symbiosis. Symbiosis is a mutually beneficial or obligatory association between two or more different species. There are three main types of symbiotic relationships:

1. Mutualism: In mutualistic symbiosis, both organisms benefit from the interaction. For example, the relationship between flowering plants and their pollinators (such as bees and butterflies). The plant provides nectar and pollen as food for the pollinator, while the pollinator helps in the plant's reproduction by transferring pollen.

2. Commensalism: In commensalism, one organism benefits, while the other is unaffected. An example is the relationship between cattle egrets and livestock. The egrets feed on insects that are disturbed by the movements of the livestock, but the livestock is unaffected.

3. Parasitism: In parasitic symbiosis, one organism (parasite) benefits at the expense of the other organism (host). For instance, a tick infesting a dog. The tick benefits from the dog's blood, while the dog is harmed by the presence of the parasite.

To identify and understand different types of symbiotic relationships, scientists often rely on observations, experiments, and ecological studies. They analyze the behaviors, interactions, and dependence between the organisms involved. Additionally, they may investigate the impact of the relationship on the survival, reproduction, or overall fitness of the organisms. By studying these factors, researchers can uncover the complexity of symbiotic relationships in the natural world.