There are three spectrins in invertebrates, α,β and βH. Mutations in βH spectrin in "C. elegans" cause defects in morphogenesis resulting in a significantly shorter, but otherwise mostly normal, animal that moves and reproduces. These animals are called "sma" for their small phenotype and carry mutations in the "C. elegans" sma-1 gene. A mutation in β spectrin in "C. elegans" results in an uncoordinated phenotype in which the worms are paralysed and much shorter than wild-type. In addition to the morphological effects, the Unc-70 mutation also produce defective neurons. Neuron numbers are normal but neuronal outgrowth was defective.