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The morphology and adhesion mechanism of Octopus vulgaris suckers.

Tramacere F, Beccai L, Kuba M, Gozzi A, Bifone A, Mazzolai B - PLoS ONE (2013)

Bottom Line: We use three different techniques (MRI, ultrasonography, and histology) and a 3D reconstruction approach to contribute knowledge on both morphology and functionality of the sucker structure in O. vulgaris.The results of our investigation are two-fold.In particular, in O. vulgaris the acetabular chamber, that is a hollow spherical cavity in other octopuses, shows an ellipsoidal cavity which roof has an important protuberance with surface roughness.

View Article: PubMed Central - PubMed

Affiliation: Center for Micro-BioRobotics, Istituto Italiano di Tecnologia, Pontedera, Italy. francesca.tramacere@iit.it

ABSTRACT
The octopus sucker represents a fascinating natural system performing adhesion on different terrains and substrates. Octopuses use suckers to anchor the body to the substrate or to grasp, investigate and manipulate objects, just to mention a few of their functions. Our study focuses on the morphology and adhesion mechanism of suckers in Octopus vulgaris. We use three different techniques (MRI, ultrasonography, and histology) and a 3D reconstruction approach to contribute knowledge on both morphology and functionality of the sucker structure in O. vulgaris. The results of our investigation are two-fold. First, we observe some morphological differences with respect to the octopus species previously studied (i.e., Octopus joubini, Octopus maya, Octopus bimaculoides/bimaculatus and Eledone cirrosa). In particular, in O. vulgaris the acetabular chamber, that is a hollow spherical cavity in other octopuses, shows an ellipsoidal cavity which roof has an important protuberance with surface roughness. Second, based on our findings, we propose a hypothesis on the sucker adhesion mechanism in O. vulgaris. We hypothesize that the process of continuous adhesion is achieved by sealing the orifice between acetabulum and infundibulum portions via the acetabular protuberance. We suggest this to take place while the infundibular part achieves a completely flat shape; and, by sustaining adhesion through preservation of sucker configuration. In vivo ultrasonographic recordings support our proposed adhesion model by showing the sucker in action. Such an underlying physical mechanism offers innovative potential cues for developing bioinspired artificial adhesion systems. Furthermore, we think that it could possibly represent a useful approach in order to investigate any potential difference in the ecology and in the performance of adhesion by different species.

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Schematic view, in four phases, of the adhesion mechanism proposed for the O. vulgaris sucker.A) Forming of a tight seal that prevents water from leaking at the rim. Infundibular radial muscles begin to contract (black arrows) to increase the contact area between (flattened) infundibulum and substrate; B) Contraction (black arrow) of acetabular radial muscles creates suction and moves water from infundibulum-substrate interface toward the acetabulum (blue arrows), as well, enhancing attachment; C) Meridional muscles of acetabulum contract (black arrows), allowing the protuberance makes contact with the upper part of the side walls of the orifice; meanwhile, the acetabular radial muscles are still contracted (gray arrow). Rough surfaces of both orifice and acetabular roof (coming into contact) contribute to adhesion. A torus of water is created in the acetabular cavity around the protuberance itself; D) Acetabular radial and meridional muscles stop to contract. The protuberance is passively kept in contact with the upper part of the side walls of the orifice, due to the cohesive force of water in the infundibular compartment and the friction of the two roughness surfaces that are in contact (acetabular protuberance and upper part of side walls of orifice). These two forces are balanced by the elastic restoring force of acetabular protuberance.
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pone-0065074-g007: Schematic view, in four phases, of the adhesion mechanism proposed for the O. vulgaris sucker.A) Forming of a tight seal that prevents water from leaking at the rim. Infundibular radial muscles begin to contract (black arrows) to increase the contact area between (flattened) infundibulum and substrate; B) Contraction (black arrow) of acetabular radial muscles creates suction and moves water from infundibulum-substrate interface toward the acetabulum (blue arrows), as well, enhancing attachment; C) Meridional muscles of acetabulum contract (black arrows), allowing the protuberance makes contact with the upper part of the side walls of the orifice; meanwhile, the acetabular radial muscles are still contracted (gray arrow). Rough surfaces of both orifice and acetabular roof (coming into contact) contribute to adhesion. A torus of water is created in the acetabular cavity around the protuberance itself; D) Acetabular radial and meridional muscles stop to contract. The protuberance is passively kept in contact with the upper part of the side walls of the orifice, due to the cohesive force of water in the infundibular compartment and the friction of the two roughness surfaces that are in contact (acetabular protuberance and upper part of side walls of orifice). These two forces are balanced by the elastic restoring force of acetabular protuberance.

Mentions: According to our morphological investigation and ultrasonographic recording results, we hypothesize that O. vulgaris sucker adheres by sealing and suction (as already described in literature) (Figure 7A and B); sealing the orifice between acetabulum and infundibulum portions via the acetabular protuberance, with the infundibular part achieving a completely flat shape (Figure 7C); sustaining adhesion through preservation of sucker configuration (Figure 7D).


The morphology and adhesion mechanism of Octopus vulgaris suckers.

Tramacere F, Beccai L, Kuba M, Gozzi A, Bifone A, Mazzolai B - PLoS ONE (2013)

Schematic view, in four phases, of the adhesion mechanism proposed for the O. vulgaris sucker.A) Forming of a tight seal that prevents water from leaking at the rim. Infundibular radial muscles begin to contract (black arrows) to increase the contact area between (flattened) infundibulum and substrate; B) Contraction (black arrow) of acetabular radial muscles creates suction and moves water from infundibulum-substrate interface toward the acetabulum (blue arrows), as well, enhancing attachment; C) Meridional muscles of acetabulum contract (black arrows), allowing the protuberance makes contact with the upper part of the side walls of the orifice; meanwhile, the acetabular radial muscles are still contracted (gray arrow). Rough surfaces of both orifice and acetabular roof (coming into contact) contribute to adhesion. A torus of water is created in the acetabular cavity around the protuberance itself; D) Acetabular radial and meridional muscles stop to contract. The protuberance is passively kept in contact with the upper part of the side walls of the orifice, due to the cohesive force of water in the infundibular compartment and the friction of the two roughness surfaces that are in contact (acetabular protuberance and upper part of side walls of orifice). These two forces are balanced by the elastic restoring force of acetabular protuberance.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3672162&req=5

pone-0065074-g007: Schematic view, in four phases, of the adhesion mechanism proposed for the O. vulgaris sucker.A) Forming of a tight seal that prevents water from leaking at the rim. Infundibular radial muscles begin to contract (black arrows) to increase the contact area between (flattened) infundibulum and substrate; B) Contraction (black arrow) of acetabular radial muscles creates suction and moves water from infundibulum-substrate interface toward the acetabulum (blue arrows), as well, enhancing attachment; C) Meridional muscles of acetabulum contract (black arrows), allowing the protuberance makes contact with the upper part of the side walls of the orifice; meanwhile, the acetabular radial muscles are still contracted (gray arrow). Rough surfaces of both orifice and acetabular roof (coming into contact) contribute to adhesion. A torus of water is created in the acetabular cavity around the protuberance itself; D) Acetabular radial and meridional muscles stop to contract. The protuberance is passively kept in contact with the upper part of the side walls of the orifice, due to the cohesive force of water in the infundibular compartment and the friction of the two roughness surfaces that are in contact (acetabular protuberance and upper part of side walls of orifice). These two forces are balanced by the elastic restoring force of acetabular protuberance.
Mentions: According to our morphological investigation and ultrasonographic recording results, we hypothesize that O. vulgaris sucker adheres by sealing and suction (as already described in literature) (Figure 7A and B); sealing the orifice between acetabulum and infundibulum portions via the acetabular protuberance, with the infundibular part achieving a completely flat shape (Figure 7C); sustaining adhesion through preservation of sucker configuration (Figure 7D).

Bottom Line: We use three different techniques (MRI, ultrasonography, and histology) and a 3D reconstruction approach to contribute knowledge on both morphology and functionality of the sucker structure in O. vulgaris.The results of our investigation are two-fold.In particular, in O. vulgaris the acetabular chamber, that is a hollow spherical cavity in other octopuses, shows an ellipsoidal cavity which roof has an important protuberance with surface roughness.

View Article: PubMed Central - PubMed

Affiliation: Center for Micro-BioRobotics, Istituto Italiano di Tecnologia, Pontedera, Italy. francesca.tramacere@iit.it

ABSTRACT
The octopus sucker represents a fascinating natural system performing adhesion on different terrains and substrates. Octopuses use suckers to anchor the body to the substrate or to grasp, investigate and manipulate objects, just to mention a few of their functions. Our study focuses on the morphology and adhesion mechanism of suckers in Octopus vulgaris. We use three different techniques (MRI, ultrasonography, and histology) and a 3D reconstruction approach to contribute knowledge on both morphology and functionality of the sucker structure in O. vulgaris. The results of our investigation are two-fold. First, we observe some morphological differences with respect to the octopus species previously studied (i.e., Octopus joubini, Octopus maya, Octopus bimaculoides/bimaculatus and Eledone cirrosa). In particular, in O. vulgaris the acetabular chamber, that is a hollow spherical cavity in other octopuses, shows an ellipsoidal cavity which roof has an important protuberance with surface roughness. Second, based on our findings, we propose a hypothesis on the sucker adhesion mechanism in O. vulgaris. We hypothesize that the process of continuous adhesion is achieved by sealing the orifice between acetabulum and infundibulum portions via the acetabular protuberance. We suggest this to take place while the infundibular part achieves a completely flat shape; and, by sustaining adhesion through preservation of sucker configuration. In vivo ultrasonographic recordings support our proposed adhesion model by showing the sucker in action. Such an underlying physical mechanism offers innovative potential cues for developing bioinspired artificial adhesion systems. Furthermore, we think that it could possibly represent a useful approach in order to investigate any potential difference in the ecology and in the performance of adhesion by different species.

Show MeSH
Related in: MedlinePlus