Attachment to challenging substrates – fouling, roughness and limits of adhesion in the northern clingfish (Gobiesox maeandricus)

Abstract

Northern clingfish use a ventral suction disc to stick to rough substrates in the intertidal zone. Bacteria, algae and invertebrates grow on these surfaces (fouling) and change the surface properties of the primary substrate, and therefore the attachment conditions for benthic organisms. In this study, we investigate the influence of fouling and surface roughness on the adhesive strength of northern clingfish, Gobiesox maeandricus. We measured clingfish tenacity on unfouled and fouled substrates over four surface roughnesses. We exposed surfaces for 6 weeks in the Pacific Ocean, until they were covered with periphyton. Clingfish tenacity is equivalent on both fouled and unfouled smooth substrates; however, tenacity on fouled rough surfaces is less compared with tenacity on unfouled ones. We hypothesize that parts of biofilm may act as a lubricant and decrease friction of the disc margin, thereby making disc margins slip inwards and fail at lower tenacities. Nevertheless, even on fouled surfaces the adhesive forces are approximately 150 times the body weight of the fish. To identify the upper threshold of surface roughness the fish can cling to, we tested seven unfouled substrates of increasing surface roughness. The threshold roughness at which northern clingfish failed increased with specimen size. We hypothesize that because of the elastic properties of the disc margin, a larger disc can adapt to larger surface irregularities. The largest specimens (length 10-12 cm) were able to cling to surfaces with 2-4 mm grain size. The fish can attach to surfaces with roughness between 2 and 9% of the suction disc width.

A new genus and species of clingfish from the Rangitāhua Kermadec Islands of New Zealand (Teleostei, Gobiesocidae)

“…Seven species also are known to inhabit freshwater streams in the Neotropics (Briggs and Miller 1960; Conway et al 2017a). Commonly referred to as clingfishes, members of this family generally exhibit a well-developed ventral adhesive disc (formed by elements of the paired fins and paired-fin girdles; Guitel 1888), with which they can attach to smooth or even heavily structured substrates with great tenacity (Wainwright et al 2013; Ditsche et al 2014). …”

The Adhesive System and Anisotropic Shear Force of Guizhou Gastromyzontidae

“…The area of the attachment disc ranged from 654 mm 2 to 895 mm 2 . In comparison to other fish species with attachment discs, such as remoras421, clingfishes122 and gobbies2324, the attachment disc of B. kweichowensis is very large in relation to the body. In addition, as shown in Fig.…”

“…As shown in Fig. 4(d), the tenacity goes down with larger surface roughness, indicating that B. kweichowensis cannot adapt to rugged substrates as well as the clingfish122.…”

Do Alluvial Sand Dunes Create Energetic Refugia for Benthic Fishes? An Experimental Test with the Endangered Pallid Sturgeon

“…The base sand habitat consisted of 60 grit sand paper (3 M, Saint Paul, Minnesota, USA) affixed to and covering the entirety of an acrylic base (6.35-mm sheeting) to simulate the surface conditions of a structureless habitat patch consisting of sand substrate (e.g. Husak, 2006;Ditsche et al, 2014). The sand dune habitat consisted of a single dune with a crest height of 8 cm structurally supported by an acrylic frame and covered entirely with the base sand substrate (Figure 1).…”