BIOLOGIYA MORYA, 2015, Vol. 41, No. 5, pp. 331-339 |
|
The morphology of the frontal filaments in the nauplii of Verruca stroemia (Müller, 1776) and Hesperibalanus hesperius (Pilsbry, 1916) (Cirripedia: Thoracica) 1Koltzov Institute of Developmental Biology, Russian Academy of Sciences, Moscow 119334; E-mail: Scanning electron microscopy was used to investigate the fine morphology of the frontal filaments (FF) in nauplial stages of the barnacles Verruca stroemia (Müller, 1776) and Hesperibalanus hesperius (Pilsbry, 1916). Changes in the FF structure in the course of development were examined. The FFs were revealed in nauplial stage II and were retained at all the subsequent nauplial stages. Small openings located either apically or subapically were found at the top of each FF in both species. In addition, the surface of FF bears longitudinal grooves. The FFs are not separated from the body, but each of them has a constriction at the base. In the nauplii of both species, the FFs have a wide proximal and a thin distal part. The area between the proximal and distal parts in V. stroemia looks like a single crease; in H. hesperius it resembles an accordion-shaped series of creases. The proximal/distal parts length ratio remains constant during all nauplial stages, but it varies between species. The proximal part constitutes 20-25% of the filament length in V. stroemia, while in H. hesperius the proximal and distal parts are approximately equal. The frontal filament length increases proportionally to the length of the larval body in the course of development. The possible functions of FFs (such as being sensitive organs), their occurrence among the crustaceans, and possible homology with the preantennal limbs are discussed. Key words: frontal filaments, scanning electron microscopy, nauplial stages, barnacles, Cirripedia. |
|
|