Development of the muscular and nervous systems during the larval ontogeny of the stalked barnacle, Octolasmis angulata Aurivillius 1894 (Cirripedia: Thoracicalcerea: Poecilasmatidae)

Abstract

The advancements in microscopic techniques have stimulated great interest in the muscular and neural architectures of invertebrates, specifically using muscle and neural structures to infer phylogenetic relationships. Here, we provide the data on the development of the muscular and nervous systems during the larval development of stalked barnacle, Octolasmis angulata using the phalloidin F-actin and immunohistochemical labelling (e.g. acetylated α-tubulin and serotonin) and confocal laser scanning microscopy analysis. All naupliar stages shared the same muscle and neural architectures with only the discrepancy in size. The nauplii have a complex muscle arrangement in their feeding apparatus and naupliar appendages. Most naupliar muscles undergo histolyse during the cyprid metamorphosis. The cyprid muscles form beneath the head shield at the end of nauplius VI. The naupliar and cyprid central nervous systems exhibit the typical tripartite brain comprising the protocerebrum, deutocerebrum and tritocerebrum. The serotonin-like immunoreactivity is mainly found in the naupliar brain, mandibular ganglia, cyprid brain and posterior ganglia. Our study revealed that numerous muscle and neural architectures in the naupliar and cyprids have phylogenetic significance, but future studies on the myoanatomy and neuroanatomy of other barnacle species are necessary to determine the homology of these structures.