What could be the energy source of a sentient, supermassive biological entity on an ocean planet?

In exploring the xenobiology and design for an entity (Entity X) in my fictional universe, I wanted to raise the viability of an organism that is so massive, it is visible from the planet's upper atmosphere. It is a biosphere unto itself. This entity is simultaneously a 'birthing farm' that reproduces asexually and also is a hive-mind, that controls an ecosystem that ensures its prolonged survival. I am thinking that this organism is fixed, much like the deep sea tube worms found near hydrothermal vents.

My fictional ocean planet is teeming with life, resources are abundant and water pressure is far, far lesser than that on Earth. This ocean isn't as deep and light from 2 distant suns is able to penetrate the depths, increasing the availability of life and food for the sub-oceanic life forms.

My current assumptions about potential energy sources for Entity X are very naive:

It derives much of the energy it requires for its sustenance from a suboceanic chemical source. Going down this path, I determined that this planet has a young core, and enough geological activity that the ocean floor is pockmarked with millions of thermal vents, which subsequently release a massive amount of chemicals, that could potentially sustain an entity as large as a mountain.

Based on that assumption, what are the energy needs of Entity X given that:

It is a hive-mind.

It reproduces on a massive scale.

EDIT: Based on suggestions, I refined my question further to simply ascertain the energy needs of Entity X.

posted over 6 years ago

frishi‭

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