Autotrophs get energy by capturing the sun's energy and converting it to sugar molecules namely glucose. This process is called "photosynthesiswhich means photo=light and synthesis=put together and make and photosynthesis refers to the process of capturing the sunlight and making food molecules such as glucose.

the species living around the vents are especially good at dispersal.  

deep-sea vent originates on the floor of the ocean when seawater circulates through hot volcanic rocks, usually situated where the new oceanic crust is being produced.  

biological dispersal refers to the movement of species from their location of birth to their site of breeding, or from breeding site to another. similarly, the oceanic dispersal refers to the movement of the species from one land mass to another by sea crossing.