sessilejä

Sessile refers to organisms that are permanently attached to a substrate, meaning they do not move from one place to another. This mode of life is common in a wide range of marine and freshwater environments, as well as in terrestrial habitats. Sessile organisms are typically found attached to rocks, coral reefs, the shells of other animals, or even man-made structures.

Examples of sessile organisms include sponges, corals, barnacles, oysters, mussels, sea anemones, and many types of algae. These organisms have evolved specialized structures or mechanisms to anchor themselves to their chosen surface. For instance, sponges secrete a sticky substance, while barnacles secrete a cement-like material.

The sessile lifestyle presents unique challenges and adaptations. Since they cannot move to find food or escape predators, sessile organisms often rely on filter-feeding, where they strain small food particles from the water column. Others, like corals and anemones, capture prey with stinging tentacles. Defense mechanisms can include hard shells, toxic secretions, or the ability to retract into protective structures. Reproduction often involves the release of gametes into the water, with larval stages that are mobile before settling down to become sessile adults. This strategy allows for dispersal to new suitable habitats.