Final answer:
A viral species is a classification of viruses based on their nucleic acid type, replication methods, and structural components like capsid shape and envelope presence.
Step-by-step explanation:
A viral species is a group of viruses that are classified based on their replication methods and the type of nucleic acid they contain. They can have DNA or RNA genomes, which may be single- or double-stranded, and their replication can involve using host cell proteins or those encoded within the viral genome. Virus classification is further delineated by structures such as the capsid shape and the presence of an envelope. The Baltimore classification system, which is based on how viruses produce their mRNA, is one commonly used method to categorize viruses. Despite this classification, much about the evolution and origins of viruses remains unknown.
Viruses display a remarkable diversity in shape and size (viruses' morphology), and they are considered acellular and parasitic, relying on their host cells for replication. They exist in a sort of netherworld, not quite alive in the traditional sense, as they do not grow, metabolize, or undergo cell division. This complexity in viral life cycle and structure, alongside the challenge in tracing their evolutionary history due to a lack of fossil record, continues to captivate virologists who endeavor to unlock the mysteries of these entities.