In one case a planarian, a type of flatworm, was cut into 279 pieces, each of which proved capable of generating a new body within a few weeks.158 Each part appears to know what it lacks, and can thus regenerate a new whole. What is still more extraordinary is that if flatworms – the ‘first’ class of organism to have a centralised brain with true synaptic transmission,159 and to share the majority of neurotransmitters that occur in vertebrate brains160 – are decapitated, they not only regrow a head, but retain their memories;
