The fishlike amphioxus has a structure called a notochord which in humans develops into this column
... all chordates display several derived structures: a dorsal hollow 
nerve cord, ... Tunicates lose their notochord as they develop into adults, but their 
larval... [DOC] [TLE] SnowTaxonomy2013 - Lancelet (chordata) [PAR] However, humans lose their tail and notochord in later embryonic ... (12) The 
feeding system has many structures that prevent large particles ...