Phylogenetics

Since the 19^th century there have been various assumptions about the phylogenetics of Holothuroidea, however only recently have the evolutionary relationships of the major holothuroid lineages been properly understood (Pearson  1914). A study conducted by Littlewood et al. in 1997, attempted to determine class-level relationships within echinoderms. They accomplished this by sequencing two ribosomal genes from four orders of Holothuria, the results revealed a close relationship between Dendrochirotida and Aspidochirotida.  In 2000 Kerr elaborated on this study and found Molpadiida to be sister to Dendrochirotida, Dactylochirotida and Aspidochirotida. These groups are united by the presence of respiratory trees (Rowe 1969).

Further studies need to be conducted using a more diverse range of mitochondrial DNA genes. This will help to gain a better understanding of the molecular phylogeny of sea cucumbers (Gilliland 1993).