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Electrosensitive spatial vectors in elasmobranch fishes: implications for source localization.

Rivera-Vicente AC, Sewell J, Tricas TC - PLoS ONE (2011)

Bottom Line: The MAN canals of all species project in anterior or posterior directions behind the mouth and likely coordinate prey capture.Vertical elevation was greatest in the BUC of the sandbar shark, restricted by the hammerhead cephalofoil and extremely limited in the dorsoventrally flattened stingray.These results are consistent with the functional subunit hypothesis that predicts specialized ampullary functions for processing of weak dipole and geomagnetic induced fields, and provides an anatomical basis for future experiments on central processing of different forms of relevant electric stimuli.

View Article: PubMed Central - PubMed

Affiliation: Department of Zoology, University of Hawaii at Manoa, Honolulu, Hawaii, United States of America.

ABSTRACT
The electrosense of sharks and rays is used to detect weak dipole-like bioelectric fields of prey, mates and predators, and several models propose a use for the detection of streaming ocean currents and swimming-induced fields for geomagnetic orientation. We assessed pore distributions, canal vectors, complementarity and possible evolutionary divergent functions for ampullary clusters in two sharks, the scalloped hammerhead (Sphyrna lewini) and the sandbar shark (Carcharhinus plumbeus), and the brown stingray (Dasyatis lata). Canal projections were determined from measured coordinates of each electrosensory pore and corresponding ampulla relative to the body axis. These species share three ampullary groups: the buccal (BUC), mandibular (MAN) and superficial ophthalmic (SO), which is subdivided into anterior (SOa) and posterior (SOp) in sharks. The stingray also has a hyoid (HYO) cluster. The SOp in both sharks contains the longest (most sensitive) canals with main projections in the posterior-lateral quadrants of the horizontal plane. In contrast, stingray SO canals are few and short with the posterior-lateral projections subsumed by the HYO. There was strong projection coincidence by BUC and SOp canals in the posterior lateral quadrant of the hammerhead shark, and laterally among the stingray BUC and HYO. The shark SOa and stingray SO and BUC contain short canals located anterior to the mouth for detection of prey at close distance. The MAN canals of all species project in anterior or posterior directions behind the mouth and likely coordinate prey capture. Vertical elevation was greatest in the BUC of the sandbar shark, restricted by the hammerhead cephalofoil and extremely limited in the dorsoventrally flattened stingray. These results are consistent with the functional subunit hypothesis that predicts specialized ampullary functions for processing of weak dipole and geomagnetic induced fields, and provides an anatomical basis for future experiments on central processing of different forms of relevant electric stimuli.

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Spherical projections for ampullary groups in the sandbar shark, hammerhead shark and brown stingray.Azimuth (θ degrees) is plotted on the X axis and elevation (ϕ degrees) plotted on the Y axis. The coordinate of 0° θ, 0° ϕ corresponds to the longitudinal axis in the horizontal plane of the animal. Values of θ between 270° and 90° represent canals that project rostrally. Negative values of ϕ indicate canals that project ventrally and positive values of ϕ canals that project dorsally. Ampullary groups are represented by different colors and symbols (BUC  =  blue squares, SOa  =  green circles, SOp  =  red triangles, HYO  =  pink diamonds). Mandibular ampullae are not shown. Symbol size corresponds to relative canal length (larger symbols  =  longer canals).
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pone-0016008-g004: Spherical projections for ampullary groups in the sandbar shark, hammerhead shark and brown stingray.Azimuth (θ degrees) is plotted on the X axis and elevation (ϕ degrees) plotted on the Y axis. The coordinate of 0° θ, 0° ϕ corresponds to the longitudinal axis in the horizontal plane of the animal. Values of θ between 270° and 90° represent canals that project rostrally. Negative values of ϕ indicate canals that project ventrally and positive values of ϕ canals that project dorsally. Ampullary groups are represented by different colors and symbols (BUC  =  blue squares, SOa  =  green circles, SOp  =  red triangles, HYO  =  pink diamonds). Mandibular ampullae are not shown. Symbol size corresponds to relative canal length (larger symbols  =  longer canals).

Mentions: Each BUC cluster in the sandbar shark is located lateral on the head with several pores that surround the eye (Fig. 2A). A total of 281 canals were counted on the left cluster of which 41% project ventrally and 59% dorsally (Table 1). Dorsal BUC canals averaged 4.55 cm in length and were divided into two subpopulations of canals based on their projection vectors. The first dorsal group showed strong projections towards the tip of the snout at ±330° alpha (Fig. 3, horizontal plane) and a vertical elevation centered around 10° θ (Fig. 4). The second dorsal population projects medially and posterolaterally towards the top of the chondrocranium (∼135° alpha on the horizontal plane, Fig. 3; 225° θ, Fig. 4) and contains the longest canals with vertical projections (225° alpha on the sagittal plane, Fig. 3; 40° ϕ, Fig. 4). The ventral BUC cluster contains the longest canals of the BUC group at 11.7 cm with mean length (4.62 cm) similar to that of the dorsal BUC group. These canals project caudally in the horizontal plane (∼165° alpha, Fig. 3). The overall range of elevation for the entire BUC cluster was from −71° to 84° ϕ (Fig. 4).


Electrosensitive spatial vectors in elasmobranch fishes: implications for source localization.

Rivera-Vicente AC, Sewell J, Tricas TC - PLoS ONE (2011)

Spherical projections for ampullary groups in the sandbar shark, hammerhead shark and brown stingray.Azimuth (θ degrees) is plotted on the X axis and elevation (ϕ degrees) plotted on the Y axis. The coordinate of 0° θ, 0° ϕ corresponds to the longitudinal axis in the horizontal plane of the animal. Values of θ between 270° and 90° represent canals that project rostrally. Negative values of ϕ indicate canals that project ventrally and positive values of ϕ canals that project dorsally. Ampullary groups are represented by different colors and symbols (BUC  =  blue squares, SOa  =  green circles, SOp  =  red triangles, HYO  =  pink diamonds). Mandibular ampullae are not shown. Symbol size corresponds to relative canal length (larger symbols  =  longer canals).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3020962&req=5

pone-0016008-g004: Spherical projections for ampullary groups in the sandbar shark, hammerhead shark and brown stingray.Azimuth (θ degrees) is plotted on the X axis and elevation (ϕ degrees) plotted on the Y axis. The coordinate of 0° θ, 0° ϕ corresponds to the longitudinal axis in the horizontal plane of the animal. Values of θ between 270° and 90° represent canals that project rostrally. Negative values of ϕ indicate canals that project ventrally and positive values of ϕ canals that project dorsally. Ampullary groups are represented by different colors and symbols (BUC  =  blue squares, SOa  =  green circles, SOp  =  red triangles, HYO  =  pink diamonds). Mandibular ampullae are not shown. Symbol size corresponds to relative canal length (larger symbols  =  longer canals).
Mentions: Each BUC cluster in the sandbar shark is located lateral on the head with several pores that surround the eye (Fig. 2A). A total of 281 canals were counted on the left cluster of which 41% project ventrally and 59% dorsally (Table 1). Dorsal BUC canals averaged 4.55 cm in length and were divided into two subpopulations of canals based on their projection vectors. The first dorsal group showed strong projections towards the tip of the snout at ±330° alpha (Fig. 3, horizontal plane) and a vertical elevation centered around 10° θ (Fig. 4). The second dorsal population projects medially and posterolaterally towards the top of the chondrocranium (∼135° alpha on the horizontal plane, Fig. 3; 225° θ, Fig. 4) and contains the longest canals with vertical projections (225° alpha on the sagittal plane, Fig. 3; 40° ϕ, Fig. 4). The ventral BUC cluster contains the longest canals of the BUC group at 11.7 cm with mean length (4.62 cm) similar to that of the dorsal BUC group. These canals project caudally in the horizontal plane (∼165° alpha, Fig. 3). The overall range of elevation for the entire BUC cluster was from −71° to 84° ϕ (Fig. 4).

Bottom Line: The MAN canals of all species project in anterior or posterior directions behind the mouth and likely coordinate prey capture.Vertical elevation was greatest in the BUC of the sandbar shark, restricted by the hammerhead cephalofoil and extremely limited in the dorsoventrally flattened stingray.These results are consistent with the functional subunit hypothesis that predicts specialized ampullary functions for processing of weak dipole and geomagnetic induced fields, and provides an anatomical basis for future experiments on central processing of different forms of relevant electric stimuli.

View Article: PubMed Central - PubMed

Affiliation: Department of Zoology, University of Hawaii at Manoa, Honolulu, Hawaii, United States of America.

ABSTRACT
The electrosense of sharks and rays is used to detect weak dipole-like bioelectric fields of prey, mates and predators, and several models propose a use for the detection of streaming ocean currents and swimming-induced fields for geomagnetic orientation. We assessed pore distributions, canal vectors, complementarity and possible evolutionary divergent functions for ampullary clusters in two sharks, the scalloped hammerhead (Sphyrna lewini) and the sandbar shark (Carcharhinus plumbeus), and the brown stingray (Dasyatis lata). Canal projections were determined from measured coordinates of each electrosensory pore and corresponding ampulla relative to the body axis. These species share three ampullary groups: the buccal (BUC), mandibular (MAN) and superficial ophthalmic (SO), which is subdivided into anterior (SOa) and posterior (SOp) in sharks. The stingray also has a hyoid (HYO) cluster. The SOp in both sharks contains the longest (most sensitive) canals with main projections in the posterior-lateral quadrants of the horizontal plane. In contrast, stingray SO canals are few and short with the posterior-lateral projections subsumed by the HYO. There was strong projection coincidence by BUC and SOp canals in the posterior lateral quadrant of the hammerhead shark, and laterally among the stingray BUC and HYO. The shark SOa and stingray SO and BUC contain short canals located anterior to the mouth for detection of prey at close distance. The MAN canals of all species project in anterior or posterior directions behind the mouth and likely coordinate prey capture. Vertical elevation was greatest in the BUC of the sandbar shark, restricted by the hammerhead cephalofoil and extremely limited in the dorsoventrally flattened stingray. These results are consistent with the functional subunit hypothesis that predicts specialized ampullary functions for processing of weak dipole and geomagnetic induced fields, and provides an anatomical basis for future experiments on central processing of different forms of relevant electric stimuli.

Show MeSH