After artificial fertilization and raising embryos in the laboratory, blastulae hatch from the vitelline membrane and begin to swim. Development occurs in the water column from gastrulation to pluteus larva stage until metamorphosis.

Stage with three pairs of arms.

Stage with three pairs of arms.

Early stage with two arms (post-oral).

Oral region.

Early stage with two arms (post-oral).

Stage with four pairs of arms.

Epithelial cells with pigmented granules during growth of antero-lateral arms (2nd pair).

Stage with four pairs of arms.

Post-oral arms of a six-arm pluteus larva.

Ambulacral feet and spines.

Stage with three pairs of arms.

Early eight-arm stage, lateral view.

Larva with six arms.

Ossicles of the lantern of Aristotle in formation at the oral region.

Oral region.

Growth of antero-lateral pair of arms (2nd pair).

Larva with three pairs of arms.

Detail of teeth in the lantern of Aristotle.

Lateral view. Detail of the lantern of Aristotle under the peristomial membrane (where mouth will open).

Detail of primary mesenchymal cells.

Aboral surface.

Oral region with the lantern of Aristotle in formation.