Termoplastid

Termoplastid is a term used in speculative biology and science fiction to describe a proposed lineage of photosynthetic eukaryotes characterized by thermally responsive plastids. In this concept, termoplastids possess plastids that can remodel their structure or pigment composition in response to ambient temperature, enabling efficient photosynthesis across a broader thermal range. The taxonomic status of termoplastids is not established; they are not recognized by major databases and are typically treated as a hypothetical clade or a thought-experiment construct rather than a formal taxon.

Physiology and morphology are described variably. Some models propose small, plastid-bearing cells with secondary plastids derived from green or red algae, whose thylakoid organization shifts with temperature. Others imagine a single, flexible plastid that alters pigment content to optimize light capture under heat stress.

Ecology and life history remain speculative. Termoplastids are imagined to inhabit environments with thermal gradients, such as geothermal springs, shallow coastal pools, or soil microhabitats. Reproduction is usually described as asexual division, though some writers speculate about facultative sexual cycles.

Significance: The concept helps explore questions about plastid evolution, organelle plasticity, and thermotolerance, but it has no standing in real taxonomy and is used mainly in fiction or speculative biology.

See also: plastid, endosymbiotic theory, thermotolerance, speculative biology.