Shell articulation in articulate brachiopods

wastedshadows's version from 2016-01-26 19:29


Brachiopods posses a calcaerous shell with a tooth and socket structure near the hinge.
  This locks together when the shell is closed so that the two valves dont slide open, especially if the brachiopod is being attacked
Also posses a pair of agnostic muscles which open and close the shell.
Adductor muscle - closes shell
Diductor muscle - opens shell
When one muscle contracts other relaxes and opens and closes shell.
When shell is opened it produces a gap known as the commisure through which water carrying food and oxygen is drawn into the mantle of the organism
There the nutrients are absorbed by a spiral structure known as a lophophore