First, I needed a producer for my ecosystem. I realized that where there is hot rock, there is light – it just doesn’t penetrate far. I thought that if a photosynthetic structure was in direct contact with the rock, it could use the light for energy. Then I thought that since the light was blackbody radiation, would that mean that the conductive heating and radiant heating would be equally efficient? Since heat can only be used as an energy source with a cooler place to dump it, and the habitat of the mantle would be relatively homogenous, I didn’t think it would work. I’m not a physicist, but my instinct tells me that any positive steps a life form might take to lower the local entropy would be equally undone by negative steps from the surrounding heat. Does anybody know whether being made of a different material from the surrounding rock would allow the life form to be affected differently by the heat and the light? Isn’t all thermal transfer by direct contact done by the exchange of electromagnetic radiation by electron shells?
To get around this problem, I imagined the photosynthetic structure behind a clear window (diamond?) so as not to be in direct contact with the hot rock. Eventually, the heat would raise everything to the same temperature, so I also had to imagine the organism to have a cooling system. Of course, cooling systems take a lot of energy to run – and always more than can be gleaned from the surrounding heat – and therefore more than from the surrounding light (assuming it is all blackbody radiation)…I’m getting carried away.
Never mind, I’ll figure it out later. Just accept that some form of algae lives in the mantle. Moving on,
As they sit in the current, algae of the fitting shape and size gets caught in the holes in the filter (B). When full, the magma mussel first closes its digestion cap (D) over the filter, and then closes the pusher cap (C), forming a seal. The pusher cap is covered with tiny knobs that line up with the holes in the filter, pushing the algae out into the digestion cavity of the digestion cap, where they digested and absorbed. When done with their meal, the magma mussels open up again to catch another.
Magma mussels are found in a variety of shapes, including those whose pusher cap hinges are ninety degrees or one hundred eighty degrees around the filter from the digestion cap hinge (or anything in between). The base of the tail can likewise be attached anywhere along the rim of the filter.
Next on the food chain, these are the magma clamps. Flexing at joint (E), they close the two halves of their digestive pouch (A) together around clusters of magma mussels. To ease in closing, trapped fluids are ejected out pores (B). Once closed, the digestion/absorption process begins and processed wastes are ejected from different pores (F). The pouch slowly flattens as it empties.
Since it is a larger organism, it grows support beams (C) to hold up the rock above it. Movements are slow enough that it has ample time to absorb old beams and grow new ones as it moves. The beams are oriented differently depending on the dimensions of the cavity it inhabits. They grow as close to vertically as possible without becoming more than three times as long as the width of the cavity. Movements in the mantle are extremely slow due to the surrounding pressurized rock, and therefore so are metabolisms. It can take a long time to catch and digest a meal. To keep from melting, life in the mantle has tungsten-based integuments and shells.
To find its prey, the magma clamp has a sonar antenna (D).
The two pictures on the left are of the algae, showing their clear (diamond?) windows.
Reader challenge: How does the apex predator move? What is better name for it than cone-face?