Marshal Hedin (CC BY-SA 2.0)
Is there a limit to how small an adult arthropod can be? If so, what is the reason for the limit?
David Bortin
Whittier, California, US
Arthropods, like everything else, must have a theoretical lower size limit. Consider the following points.
Quantum physicists know that no physical object can have a dimension smaller than a Planck length, or about 1.6 × 10-35 metres.
Organic chemists know that living tissue must contain carbon-based macromolecules, such as DNA, which are typically around 0.001 micrometres in diameter.
Semanticists don’t all agree whether a virus particle is living or just a complicated complex of…
