Early 2-arm stage showing the gut between the developing coelomic sacs.

Stage with three pairs of arms.

Accelerated 6x.

Frontal view of the eight-arm pluteus larva.

Aboral surface (opposite to mouth).

Structure in the anal region.

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

Blastopore and ring of mesenchyme cells secreting the larval skeleton.

Stage with three pairs of arms.

Oral region.

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

Early stage with two arms (post-oral).

Regression of larval tissues. Spicules of the larval skeleton are still present in the aboral region.

Lateral view focusing the micromeres.

Larva with six arms.

Primary mesenchymal cells secreting the larval skeleton.

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

Stage with three pairs of arms.

Early with two arms.

Structure in the anal region.

Early with two arms.

Larva with three pairs of arms.

Aboral surface.

Oral region.