Sessile organisms provide new ecological niches and determine an increase in species diversity. This results in an augmentation of the competition and coo- peration phenomena inside the community with related adaptive evolutionary processes. In fact, within the community biological conditioning is important.

Why is it important for sessile living organisms to have a mobile life stage?

Sessile organisms such as barnacles and tunicates need some mechanism to move their young into new territory. This is why the most widely accepted theory explaining the evolution of a larval stage is the need for long-distance dispersal ability.

What does it mean to be sessile in biology?

1 : attached directly by the base : not raised upon a stalk or peduncle a sessile leaf sessile bubbles. 2 : permanently attached or established : not free to move about sessile sponges and coral polyps.