First evidence for temporary and permanent adhesive systems in the stalked barnacle cyprid, Octolasmis angulata

Fook Choy Yap,Wey-Lim Wong,Aaron G Maule,Ving Ching Chong,Lee Hong Susan Lim,Gerard P Brennan

doi:10.1038/srep44980

Fook Choy Yap, Wey-Lim Wong + Show 4 more

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https://doi.org/10.1038/srep44980

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Abstract

Although there have been extensive studies on the larval adhesion of acorn barnacles over the past few decades, little is known about stalked barnacles. For the first time, we describe the larval adhesive systems in the stalked barnacle, Octolasmis angulata and the findings differ from previous reports of the temporary (antennulary) and cement glands in thoracican barnacles. We have found that the temporary adhesives of cyprid are produced by the clustered temporary adhesive glands located within the mantle, instead of the specialised hypodermal glands in the second antennular segment as reported in the acorn barnacles. The temporary adhesive secretory vesicles (TASV) are released from the gland cells into the antennule via the neck extensions of the glands, and surrounded with microtubules in the attachment disc. Cement glands undergo a morphological transition as the cyprid grows. Synthesis of the permanent adhesives only occurs during the early cyprid stage, and is terminated once the cement glands reach maximum size. Evidence of the epithelial invaginations on the cement glands supports the involvement of exocytosis in the secretion of the permanent adhesives. This study provides new insight into the larval adhesives system of thoracican barnacles.

Highlights

There have been extensive studies on the larval adhesion of acorn barnacles over the past few decades, little is known about stalked barnacles
We describe the larval adhesive systems in the stalked barnacle, Octolasmis angulata and the findings differ from previous reports of the temporary and cement glands in thoracican barnacles
These two systems consist of the temporary adhesive glands and cement glands that are responsible for production of the temporary and permanent adhesives, respectively (Fig. 1c)

Summary

Introduction

There have been extensive studies on the larval adhesion of acorn barnacles over the past few decades, little is known about stalked barnacles. Nott and Foster[24] found the presence of numerous unicellular glands in the second and third (attachment disc) segment of the antennule, which led to an alternative hypothesis that highlighted the involvement of adhesive secretion in the temporary adhesion mechanisms. This alternative hypothesis was supported by Walker and Yule[2] who were the first to discover the deposition of the footprint material that was secreted by the cyprid for reversible temporary adhesion during the exploratory phase. The introduction of larval Octolasmis species cultured under laboratory conditions has solved this issue[40,41,42]

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