Investigating the molecular basis of notochord loss in Molgula occulta via transcriptome sequencing

Ascidian tsessile hermaphroditic filter-feeders found in marine environments (Huber et al ., 2000). Tunicates are urochordates (i.e.) because they possess the defining chordate structure, the notochord, in a larval tail that is reabsorbed upon metamorphosis. This tail is believed to benefit progeny by facilitating motility, which in turn permits a wider variety of anchoring environments and a higher probability of finding favorable settling conditions (Huber et al ., 2000). Despite the utility of this adaptation the larval notochord has been independently lost several times among the ascidians (Huber et al ., 2000). These anural, or tailless, tunicates occur with the highest frequency in the Molgulidae family (Huber et al ., 2000)