Final answer:
Green-haired, photosynthetic rats would require a novel classification, possibly as photoautotrophs, an unprecedented category in the animal kingdom that resembles gene transfer seen in aphids with fungi. This hypothetical classification would challenge existing biological categorizations.
Step-by-step explanation:
The classification for green-haired rats that are photosynthetic would likely be an unprecedented category as such organisms do not exist in reality. However, for theoretical discussion, if we assume that the green-haired rats can perform photosynthesis like green algae and plants, then they could be classified as photoautotrophs. These organisms would have a unique ability among animals, akin to the gene transfer in aphids that acquired carotenoid-synthesizing genes from fungi through horizontal gene transfer (HGT).
Since this is an extraordinary and hypothetical scenario, scientists would need to carefully study the rats to determine how they manage to perform photosynthesis, a trait found in plants, some bacteria, and protists, but not in animals. The example of dimorphic stems in Equisetum ravens demonstrates that within a single plant, different types of stems can exhibit different functionalities: green, photosynthetic stems and brown, non-photosynthetic, fertile stems. The classification of such green-haired rats would no doubt be a scientific curiosity and would perhaps require a reevaluation of our current biological categorizations.