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The coelacanth rostral organ is a unique low-resolution electro-detector that facilitates the feeding strike.

Berquist RM, Galinsky VL, Kajiura SM, Frank LR - Sci Rep (2015)

Bottom Line: This morphology facilitates neural encoding of local electric field intensity, orientation, and polarity, used for determining the position of nearby prey.The coelacanth rostral organ electric sense, however, is unique in having only three paired sensory canals with distribution restricted to the dorsal snout, raising questions about its function.This identified a unique focal region of electrosensitivity directly in front of the mouth, and is the first evidence of a low-resolution electro-detector that solely facilitates prey ingestion.

View Article: PubMed Central - PubMed

Affiliation: Center for Scientific Computation in Imaging, Department of Radiology, University of California San Diego, La Jolla, California 92037.

ABSTRACT
The cartilaginous and non-neopterygian bony fishes have an electric sense typically comprised of hundreds or thousands of sensory canals distributed in broad clusters over the head. This morphology facilitates neural encoding of local electric field intensity, orientation, and polarity, used for determining the position of nearby prey. The coelacanth rostral organ electric sense, however, is unique in having only three paired sensory canals with distribution restricted to the dorsal snout, raising questions about its function. To address this, we employed magnetic resonance imaging methods to map electrosensory canal morphology in the extant coelacanth, Latimeria chalumnae, and a simple dipole 'rabbit ears' antennae model with toroidal gain function to approximate their directional sensitivity. This identified a unique focal region of electrosensitivity directly in front of the mouth, and is the first evidence of a low-resolution electro-detector that solely facilitates prey ingestion.

No MeSH data available.


Related in: MedlinePlus

Morphology of the rostral organ electric sense in the extant coelacanth, L. chalumnae.MRI grey-scale data showing (a) axial, (b) horizontal, and (c) sagittal plane cross-sectional slices through the head at the location of the rostral organ. (d) 3D reconstruction from image segmentation of MRI grey-scale data showing in situ rostral organ morphology (depicted in blue). A selection of rostral organ structures have been annotated following the terminologies of Bemis & Hetherington14 with abbreviations provided below. The rostral sac (RS) resides within the median rostral cavity in the ethmoid portion of the chondrocranium. It contains all of the electrosensory epithelia and comprises a system of crypts that are invaginated into the rostral sac tissues. Three pairs of tubules radiate out from the rostral sac to pores opening on the surface of the snout. These bilaterally paired tubules comprise the anterior (A), posterior inferior (PI), and the posterior superior (PS) tubules. Note that in life, the spaces within the rostral sac and tubule systems are filled with a gelatinous substance that was stripped away as a result of tissue fixation and preservation. The thin layer of fatty tissue that surrounds the tubules and rostral sac in life has similarly been lost. Abbreviations: A, anterior tubule; LL, lateral line canal; OS, olfactory structures; PI, posterior inferior tubule; PIL, left posterior inferior tubule; PIR, right posterior inferior tubule; PS, posterior superior tubule; RS, rostral sac.
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f1: Morphology of the rostral organ electric sense in the extant coelacanth, L. chalumnae.MRI grey-scale data showing (a) axial, (b) horizontal, and (c) sagittal plane cross-sectional slices through the head at the location of the rostral organ. (d) 3D reconstruction from image segmentation of MRI grey-scale data showing in situ rostral organ morphology (depicted in blue). A selection of rostral organ structures have been annotated following the terminologies of Bemis & Hetherington14 with abbreviations provided below. The rostral sac (RS) resides within the median rostral cavity in the ethmoid portion of the chondrocranium. It contains all of the electrosensory epithelia and comprises a system of crypts that are invaginated into the rostral sac tissues. Three pairs of tubules radiate out from the rostral sac to pores opening on the surface of the snout. These bilaterally paired tubules comprise the anterior (A), posterior inferior (PI), and the posterior superior (PS) tubules. Note that in life, the spaces within the rostral sac and tubule systems are filled with a gelatinous substance that was stripped away as a result of tissue fixation and preservation. The thin layer of fatty tissue that surrounds the tubules and rostral sac in life has similarly been lost. Abbreviations: A, anterior tubule; LL, lateral line canal; OS, olfactory structures; PI, posterior inferior tubule; PIL, left posterior inferior tubule; PIR, right posterior inferior tubule; PS, posterior superior tubule; RS, rostral sac.

Mentions: The electrosensory anatomy of Latimeriachalumnae observed in cross-sectional MRI slices (Fig. 1a–c) agreed well with existing anatomical descriptions using dissection material121314. Results of three-dimensional image segmentation however, identified some features of the coelacanth electric sense not previously reported (Fig. 1d). All rostral organ tubules were approximately equivalent in length and volume, indicating similar sensitivities to electric field strength19 (Table 1). We also found the range of tubule orientations in the rostral organ array to be relatively restricted when compared with the small amount of data available on other fishes1920, with a maximum range in vertical inclination (∝v) of only 91.3°, and maximum range in rotation angle in the horizontal plan (∝h) of 253° (Table 2).


The coelacanth rostral organ is a unique low-resolution electro-detector that facilitates the feeding strike.

Berquist RM, Galinsky VL, Kajiura SM, Frank LR - Sci Rep (2015)

Morphology of the rostral organ electric sense in the extant coelacanth, L. chalumnae.MRI grey-scale data showing (a) axial, (b) horizontal, and (c) sagittal plane cross-sectional slices through the head at the location of the rostral organ. (d) 3D reconstruction from image segmentation of MRI grey-scale data showing in situ rostral organ morphology (depicted in blue). A selection of rostral organ structures have been annotated following the terminologies of Bemis & Hetherington14 with abbreviations provided below. The rostral sac (RS) resides within the median rostral cavity in the ethmoid portion of the chondrocranium. It contains all of the electrosensory epithelia and comprises a system of crypts that are invaginated into the rostral sac tissues. Three pairs of tubules radiate out from the rostral sac to pores opening on the surface of the snout. These bilaterally paired tubules comprise the anterior (A), posterior inferior (PI), and the posterior superior (PS) tubules. Note that in life, the spaces within the rostral sac and tubule systems are filled with a gelatinous substance that was stripped away as a result of tissue fixation and preservation. The thin layer of fatty tissue that surrounds the tubules and rostral sac in life has similarly been lost. Abbreviations: A, anterior tubule; LL, lateral line canal; OS, olfactory structures; PI, posterior inferior tubule; PIL, left posterior inferior tubule; PIR, right posterior inferior tubule; PS, posterior superior tubule; RS, rostral sac.
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f1: Morphology of the rostral organ electric sense in the extant coelacanth, L. chalumnae.MRI grey-scale data showing (a) axial, (b) horizontal, and (c) sagittal plane cross-sectional slices through the head at the location of the rostral organ. (d) 3D reconstruction from image segmentation of MRI grey-scale data showing in situ rostral organ morphology (depicted in blue). A selection of rostral organ structures have been annotated following the terminologies of Bemis & Hetherington14 with abbreviations provided below. The rostral sac (RS) resides within the median rostral cavity in the ethmoid portion of the chondrocranium. It contains all of the electrosensory epithelia and comprises a system of crypts that are invaginated into the rostral sac tissues. Three pairs of tubules radiate out from the rostral sac to pores opening on the surface of the snout. These bilaterally paired tubules comprise the anterior (A), posterior inferior (PI), and the posterior superior (PS) tubules. Note that in life, the spaces within the rostral sac and tubule systems are filled with a gelatinous substance that was stripped away as a result of tissue fixation and preservation. The thin layer of fatty tissue that surrounds the tubules and rostral sac in life has similarly been lost. Abbreviations: A, anterior tubule; LL, lateral line canal; OS, olfactory structures; PI, posterior inferior tubule; PIL, left posterior inferior tubule; PIR, right posterior inferior tubule; PS, posterior superior tubule; RS, rostral sac.
Mentions: The electrosensory anatomy of Latimeriachalumnae observed in cross-sectional MRI slices (Fig. 1a–c) agreed well with existing anatomical descriptions using dissection material121314. Results of three-dimensional image segmentation however, identified some features of the coelacanth electric sense not previously reported (Fig. 1d). All rostral organ tubules were approximately equivalent in length and volume, indicating similar sensitivities to electric field strength19 (Table 1). We also found the range of tubule orientations in the rostral organ array to be relatively restricted when compared with the small amount of data available on other fishes1920, with a maximum range in vertical inclination (∝v) of only 91.3°, and maximum range in rotation angle in the horizontal plan (∝h) of 253° (Table 2).

Bottom Line: This morphology facilitates neural encoding of local electric field intensity, orientation, and polarity, used for determining the position of nearby prey.The coelacanth rostral organ electric sense, however, is unique in having only three paired sensory canals with distribution restricted to the dorsal snout, raising questions about its function.This identified a unique focal region of electrosensitivity directly in front of the mouth, and is the first evidence of a low-resolution electro-detector that solely facilitates prey ingestion.

View Article: PubMed Central - PubMed

Affiliation: Center for Scientific Computation in Imaging, Department of Radiology, University of California San Diego, La Jolla, California 92037.

ABSTRACT
The cartilaginous and non-neopterygian bony fishes have an electric sense typically comprised of hundreds or thousands of sensory canals distributed in broad clusters over the head. This morphology facilitates neural encoding of local electric field intensity, orientation, and polarity, used for determining the position of nearby prey. The coelacanth rostral organ electric sense, however, is unique in having only three paired sensory canals with distribution restricted to the dorsal snout, raising questions about its function. To address this, we employed magnetic resonance imaging methods to map electrosensory canal morphology in the extant coelacanth, Latimeria chalumnae, and a simple dipole 'rabbit ears' antennae model with toroidal gain function to approximate their directional sensitivity. This identified a unique focal region of electrosensitivity directly in front of the mouth, and is the first evidence of a low-resolution electro-detector that solely facilitates prey ingestion.

No MeSH data available.


Related in: MedlinePlus