Decapodiformes
Decapodiformes is a superorder of Cephalopoda comprising all cephalopod species with ten limbs, specifically eight short arms and two long tentacles. It is hypothesized that the ancestral coleoid had five identical pairs of limbs, and that one branch of descendants evolved a modified arm pair IV to become the Decapodiformes, while another branch of descendants evolved and then eventually lost its arm pair II, becoming the Octopodiformes.
Taxonomy
The following orders are recognised in the superorder Decapodiformes:- Bathyteuthida
- †Belemnitida
- †Diplobelida
- Idiosepida – pygmy squid
- Myopsida – coastal squid
- Oegopsida – neritic squid
- Sepiida – cuttlefish
- Sepiolida – bobtail and bottletail squid
- Spirulida – ram's horn squid
Phylogeny
Molecular analyses consistently showed that the order Teuthida is invalid as its two constituent subgroups do not form a clade that did not exclude other decapodiform orders. Thus, Teuthida is presently considered an invalid order due to lack of monophyly.Maximum [likelihood phylogenetic tree|Maximum Likelihood (ML) cladogram] from Uribe & Zardoya 2017, based on complete mt genomes :
The following cladogram is based on a RAxML maximum likelihood phylogram from Anderson & Lindgren 2021: