Morphology of the Cement Apparatus and the Cement of the Buoy Barnacle Dosima fascicularis (Crustacea, Cirripedia, Thoracica, Lepadidae)

Abstract

Barnacles produce a proteinaceous adhesive called cement to attach permanently to rocks or to other hard substrata. The stalked barnacle Dosima fascicularis is of special interest as it produces a large amount of foam-like cement that can be used as a float. The morphology of the cement apparatus and of the polymerized cement of this species is almost unknown. The current study aims at filling these gaps in our knowledge using light and electron microscopy as well as x-ray microtomography. The shape of the cement gland cells changes from round to ovoid during barnacle development. The cytoplasm of the gland cells, unlike that of some other barnacles, does not have distinct secretory and storage regions. The cement canals, which transport the cement from the gland cells to the base of the stalk, end at different positions in juvenile and mature animals. With increasing size of the cement float, the exit of the cement canals shift from the centrally positioned attachment disk of the vestigial antennules to more lateral positions on the stalk. The bubbles enclosed in the foam-like float are most likely filled with CO(2) that diffuses from the hemolymph into the cement canal system and from there into the cement.

Biochemical analyses of the cement float of the goose barnacleDosima fascicularis– a preliminary study

“…The holdfast system of the barnacle differs from that of mytilid mussels and sabellariid polychaetes by the lack of a detectable L-DOPA system and the slow curing process of the adhesive (Naldrett 1993;Kamino et al 1996;Kamino 2010;Nicklisch & Waite 2012). Barnacle cement is produced by unicellular glands throughout the lifetime of the animal in accordance with its moulting cycle Fyhn & Costlow 1976;Jonker et al 2012;Zheden et al 2012). Two types of adhesive can be distinguished: the primary cement, produced while the animal is attached to a substratum, and the secondary cement, secreted when the animal is injured or detached Kamino et al 1996).…”

“…It is unique among the barnacles due to the amount and morphological structure of the cement it produces. It secretes layer by layer an excess amount of foam-like cement (Zheden et al 2012) (Figure 1 and Supplementary Figure S1). [Supplementary material is available via a multimedia link on the online article webpage.]…”

“…[Supplementary material is available via a multimedia link on the online article webpage.] The bubbles in the foam-like cement are probably filled with CO 2 , a metabolic product of the haemolymph (Zheden et al 2012). As the animal grows, small substrata such as feathers or pieces of seaweed can be surrounded and sometimes enclosed by the enlarging cement, which then forms a float (Figure S1a, b).…”

Dosima fascicularis (Cirripedia: Lepadidae) in Uruguayan waters: the southernmost western Atlantic presence of the ‘blue goose barnacle’

“…Dosima fascicularis is characterized by the presence of thin and delicate plates, and a ball-shaped body surrounding the distal part of the peduncle (Darwin, 1852;Young, 1990;Hinojosa et al, 2006). The ball is secreted from the cement glands and consists of numerous gas-filled chambers that serve as a flotation device to keep the organism at the seaair interface (Darwin, 1852;Boetius, 1952Boetius, -1953Zheden et al, 2012). Additionally, D. fascicularis exhibits a blue coloration typically observed in other euneustonic species (i.e.…”

“…These authors determined that the cement is composed mainly of acid proteins and differs from other cirripeds (balanids) having a distinctly higher proportion of glutamic acid and smaller quantities of lysine, histidine and tyrosine which could be providing a spongy mass which will act as a float rather than a strong adhesive structure. This cement usually forms an oval, whitish-beige foam-like float that may enclose the initial substratum (Zheden et al, 2012). Cheng & Lewin (1976) observed that the majority of the Dosima recorded on the coast of California were attached to a noticeable substrate as feathers or brown algae or unattached (at least noticeably) with a minor proportion attached to tar lumps.…”