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

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.

Sponge symbiosis is facilitated by adaptive evolution of larval sensory and attachment structures in barnacles

“…Our results suggest that also the pattern of cuticular villi on the attachment disc may have evolved to counteract the surface properties of the host. The villi on the attachment disc are believed to play a key part in temporary and permanent adhesion of barnacle cyprids, but although studied with advanced techniques such as atomic force microscopy their function remain largely unexplained [53][54][55]. Our study is one of the few to have focused on differences in these villi between species, and the distinct differences documented here underline their putative role.…”

Biochemistry of Barnacle Adhesion: An Updated Review

“…In acorn barnacle cyprids, the temporary adhesive was thought to be synthesized in unicellular antennal glands (Figure 2A) located in the second segment of the antennules (Nott, 1969;Nott and Foster, 1969). In the cyprid of the stalked barnacle, Octolasmis angulata, this adhesive is produced in the unicellular glands clustered in the main body (Yap et al, 2017). Synthesized temporary adhesives are then delivered to the attachment discs through the ducts in the antennules.…”

“…In acorn barnacle cyprids, the permanent cement gland is kidney-shaped, distributed at the posterior of the compound eyes, and contains two types of cells (Figure 2A; Walker, 1971;Gohad et al, 2014), while the unicellular temporary adhesive gland is located in the second segment of the antennules (Nott, 1969;Nott and Foster, 1969). In the cyprid of the stalked barnacle, O. angulata, the permanent adhesive gland is rod-shaped and located at the back of the compound eyes, while the temporary adhesive gland is oval and buried in the mantle of the body (Yap et al, 2017).…”

Properties of temporary adhesion systems of marine and freshwater organisms

“…While testing suitable surfaces, the cyprids rapidly attach and detach using their paired antennules (see Glossary) (Walker, 1981;Aldred and Clare, 2008). The morphology of the cyprid adhesive system has been comprehensively described in various species, and it appears that the temporary glue is produced in different gland cells than the later secreted permanent cement (Nott and Foster, 1969;Walker, 1971;Yap et al, 2017). In the stalked barnacle Octolasmis angulata, the temporary adhesive glands of the cyprid are located within the mantle and form long, vesicle-filled necks to the adhesive area at the tip of the antennules.…”

“…In the stalked barnacle Octolasmis angulata, the temporary adhesive glands of the cyprid are located within the mantle and form long, vesicle-filled necks to the adhesive area at the tip of the antennules. The second described gland type comprises the permanent cement and a releasing gland is apparently absent (Yap et al, 2017). Sometimes the presence of only one cell gland type immediately rules out the possibility of a duo-gland adhesive system.…”