Figure 1.
Three developmental stages of the life cycle of Balanus amphitrite.
An exploring cyprid walking close to a metamorphosing specimen and a juvenile barnacle.
Figure 2.
The six phases of metamorphosis of Balanus amphitrite.
All specimens are schematically drawn from dorsal (central column) and lateral (left column) view. See Table 1 for more details. Phase 1, cemented cyprid: the specimen can still move its body by contractions of the antennular muscles as in exploring cyprids (arrows). Phase 3, progression of metamorphosis: the specimen’s body is raised from the substratum (arrow). Phase 4, shedding of the carapace: carapace slides off the juvenile through the ventral opening of the mantle cavity (arrows). Phase 6, juvenile: long and annulated thoracopods extended well outside the mantle cavity for feeding (arrow).
Table 1.
Duration and main features of the six phases of metamorphosis of Balanus amphitrite.
Figure 3.
Attachment of a recently cemented cyprid and of an early juvenile.
A, a recently cemented cyprid, lateral view. B, higher magnification of A showing the attachment point of the antennules. C, an early juvenile. D, higher magnification of C showing the attachment point of the antennules.
Figure 4.
The rotation of the thorax inside the carapace.
A, CLSM image of a cemented cyprid showing the thorax with its anterior-posterior axis (arrow) more or less parallel to the anterior-posterior axis of the carapace and a wide anterior mantle cavity (dotted circle) hosting the antennules (very bright in the picture) and the compound eyes (not clearly visible in the picture). B, same as A with bright field. C, CLSM image of a specimen in early metamorphosis (phase 2) showing the rotation of the thorax inside the carapace (arrow identifies approximately the same axis as in A) and a much reduced anterior mantle cavity (dotted circle). D, same as C with bright field.