Segmentation in Arthropods

Face it - you've always wanted to know whether segmentation was present in the common ancestor of the bilaterians, and whether the modes of segmentation in (say) different arthropod groups reflect divergence from an ancestral mechanism, or whether they are independently derived in the different lineages. Your genes say one thing, your fossils and embryos say another. What to do? What to DO??

Fret no more - my good friend Dr Ariel Chipman from the Hebrew University of Jerusalem will set you straight. I like this video because we humans use the delta-notch signalling pathway (as do other chordates) to set up our somites and hence our body segments, and it's interesting to see how other critters accomplish this remarkable feat that is segmentation.