Aculifera

Chiton

• Wurmmollusken ( Aplacophora )
• Chitons ( Polyplacophora )

The spiked molluscs ( Aculifera, synonym Amphineura ) include within the molluscs ( Mollusca ) of the groups Wurmmollusken ( Aplacophora ) consisting of the Schildfüßern ( Caudofoveata ) and the Furchenfüßern ( Solenogastres ) and chitons ( Polyplacophora ).

This group is justified by the absence or the replacement of mollusc shells by calcium deposits in the skin. In the case of Wurmmollusken it involves spicules, known as spicules. The chitons have a calcareous shell, which consists of eight calcareous plates, which rests on the backs of the animals. Other apomorphies of the group are the subterminal anus, and a nerve ring around the anus.

The Aculifera the group of shell molluscs ( Conchifera ) is compared with:

Chitons ( Polyplacophora )

Schildfüßer ( Caudofoveata )

Furchenfüßer ( Solenogastres )

Helcionelliden ( Helcionellida ) †

Cephalopods ( Cephalopoda )

Contracts Manager ( Monoplacophora )

Snails ( Gastropoda )

Schnabel Schaler ( rostroconchs ) †

Mussels ( Bivalvia )

This group formation is compared with another theory that sees the Aculifera as non-natural group ( Paraphylum ). In this theory, the Solenogastres together with all other molluscs form the sister group of the Caudofoveata and the Polyplacophora with the remaining mollusks the sister group to the Solenogastres:

Solenogastres

Chitons ( Polyplacophora )

Conchifera (see above)

Caudofoveata

The theory that the Wurmmollusken is the sister group of all other Molluskengruppe, was already represented.

Schildfüßer ( Caudovoveata )

Furchenfüßer ( Solenogastres )

Chitons ( Polyplacophora )

Shell molluscs ( Conchifera )