Drosophila melanogaster (the common fruit fly)
Drosophila has a genome that is slightly larger than that of C. elegans but is still quite small at only 4 chromosome pairs and 1.6x108 base pairs. Its life cycle takes 10 days. The larva hatches 22 hours after fertilization. The entire genome has been sequenced and is available at http://www.fruitfly.org.
As shown in the figure below, Drosophila embryos have 3 thoracic and 8 abdominal segments, allowing easy identifications of body plan mutants.
Halteres. Balancers which form in third thoracic segment.
Wings. Normally form in second thoracic segment. Wild type have only two wings, making Drosophila dipterans.
Bicoid. Contains homebox.
Even-skipped. Contains homeobox.
Engrailed. Contains homeobox.