Does a nano-scale nipple array (moth-eye structure) suppress the settlement of ascidian larvae?

Abstract

In some metazoans, the body surface is entirely or partly covered with an array of nipples about 100 nm or less in height. This structure, a nipple array, is sometimes called the moth-eye structure because it serves as an anti-reflection property on the compound eyes of a night moth. The nipple array is supposed to be a multifunctional structure since this structure occurs in various species across different taxa. Here, we hypothesize that the nipple array may prevent the settlement of epibionts that are often a nuisance and potentially cause serious problems for the host. Using a synthetic film that imitates the nipple array, we tested the substrate selection within ascidian larval settlement. The results indicate that the nipple array has anti-fouling properties, since more larvae settled on the flat surface than the nipple array (P < 0.01, paired t-test). The present results demonstrated that the nipple array potentially serves an anti-fouling function on the body surface, which should be important especially for sessile organisms.

Substrate Selection of Ascidian Larva: Wettability and Nano-Structures

“…MOSMITE TM is a synthetic film for anti-reflection that namely mimics the moth-eye structure [59], with a nano-structure made of acrylic resin coating a base film made of polyethylene terephthalate. To evaluate whether the nipple array affects the substrate preference of ascidian larvae, we performed a dual-choice test with P. philippinensis larvae using MOSMITE TM and a flat film made of the same material, i.e., the base film coated with acrylic resin, as control [8]. The ascidian larvae significantly preferred the flat surface to MOSMITE TM for settlement.…”

“…Laboratory experiments are mainly carried out to examine particular factor(s), such as texture, wettability, or color of substrata, on pre-settlement selection, but as results do not always reflect the natural settlement process, care should be taken in interpreting these results. These experiments can be subdivided into single-choice [3][4][5][6], dual-choice [7,8], and multi-choice tests [9][10][11].…”

Exumbrellar Surface of Jellyfish: A Comparative Fine Structure Study with Remarks on Surface Reflectance

“…Figure 8 shows simplified schemas of the exumbrellar microvilli and cuticular nipple arrays, although we should consider that the length (height) and densities of the nipples vary among the parts of the body/colony (Hirose et al, 1990;Sakai et al, 2018). The nipple arrays are known to aid various functional properties associated with the body surface: reduction of light reflection (e.g., Bernhard, 1967;Wilson and Hutley, 1982;Hirose et al, 2015), reduction of air bubble adhesion (Hirose et al, 2013) and of debris (Peisker and Gorb, 2010), suppression of cell attachment (Nomura et al, 2005;Ballarin et al, 2015) and of biofouling (Hirose and Sensui, 2019). It is possible that the microvilli provide similar surface properties to the nipple arrays.…”

Observations on the Surface Structure of Aurelia solida (Scyphozoa) Polyps and Medusae

“…In addition to the transparent body, specific surface structures with anti-reflective properties can achieve reduced visibility in the water column [3,4]. Such a structure can help suppress biofouling [5] and reduce debris and bubble adhesion [6]. Free-drifting scyphomedusae are among the characteristic gelatinous organisms.…”