On the planet, insects have the biggest number in the varieties of species. Insects occupy 75% of all the living species in record globally. One of the reasons why insects have evolved in so many ways is specialization of their mouths. The mouths enabled the insects to have various ways of food intake.

Professor Ryuichiro Machida, Faculty of Life and Environmental Sciences at the University of Tsukuba conducted the functional morphological research using synchrotronμCT by the collaboration project among Japan, Germany and Switzerland. His team identified the ancestral type of insect mouth with its type of non-destructive insects.

This research confirmed that a mouth shape of ancestral insects was a type that works with structural mouthpart interaction (SMI). The result disproved the previous perception regarding ancestral insects; the ancestral insects originally had a mouth without SMI. That means, the evolution would have occurred as such: at first, ancestral insects had mouths that worked by SMI. Secondarily, dragonflies and bugs emerged with mouths that lost SMI. Then, cicadas, bees and butterflies(absorbing mouth) as well as flies (lapping mouth) appeared and had mouths with various types of SMI. This time the study gives us a brand-new perception to the evolution of insects' mouths.

Evolution of structural mouthpart interactions in insects mapped on a transcriptome-based phylogenetic tree and divergence time estimates.
Shapes of mouthparts and articulation points are shown as simplified models, mandible and maxilla movements with red and blue arrows respectively. Note that the same forms of interaction points indicate putative homologous structures across taxa.

Original Paper