Brain Size and Brain Organization of the Whale Shark, Rhincodon typus, Using Magnetic Resonance Imaging
Very little is known about the brain organization of the suction filter feeder, Rhincodon typus, and how it compares to other orectolobiforms in light of its specialization as a plankton-feeder. Brain size and overall brain organization was assessed in two specimens of R. typus in relation to both p...
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Online Access: | http://dx.doi.org/10.1159/000235962 https://www.karger.com/Article/Pdf/235962 |
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crskarger:10.1159/000235962 2024-09-30T14:33:42+00:00 Brain Size and Brain Organization of the Whale Shark, Rhincodon typus, Using Magnetic Resonance Imaging Yopak, Kara E. Frank, Lawrence R. 2009 http://dx.doi.org/10.1159/000235962 https://www.karger.com/Article/Pdf/235962 en eng S. Karger AG https://www.karger.com/Services/SiteLicenses https://www.karger.com/Services/SiteLicenses Brain, Behavior and Evolution volume 74, issue 2, page 121-142 ISSN 0006-8977 1421-9743 journal-article 2009 crskarger https://doi.org/10.1159/000235962 2024-09-04T04:07:32Z Very little is known about the brain organization of the suction filter feeder, Rhincodon typus, and how it compares to other orectolobiforms in light of its specialization as a plankton-feeder. Brain size and overall brain organization was assessed in two specimens of R. typus in relation to both phylogeny and ecology, using magnetic resonance imaging (MRI). In comparison to over 60 other chondrichthyan species, R. typus demonstrated a relatively small brain for its body size (expressed in terms of encephalization quotients and residuals), similar to the lamniforms Carcharodon carcharias, Cetorhinus maximus, and Carcharias taurus. R. typus possessed a relatively small telencephalon with some development of the dorsal pallium, which was suggestive of moderate social behavior, in addition to a relatively large diencephalon and a relatively reduced mesencephalon. The most notable characteristic of the brain of Rhincodon was a large and highly foliated cerebellum, one of the largest cerebellums within the chondrichthyan clade. Early development of the brain was qualitatively assessed using an in situ MRI scan of the brain and chondrocranium of a neonate specimen of R. typus. There was evidence that folding of the cerebellar corpus appeared in early development, although the depth and number of folds might vary ontogenetically in this species. Hierarchical cluster analysis and multidimensional scaling ordinations showed evidence of convergent evolution with the basking shark, Cetorhinus maximus, another large-bodied filter feeding elasmobranch, supporting the claim that organization of the brain is more similar in species with analogous but independently evolved lifestyles than those that share taxonomic classification. Article in Journal/Newspaper Cetorhinus maximus Karger Brain, Behavior and Evolution 74 2 121 142 |
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Very little is known about the brain organization of the suction filter feeder, Rhincodon typus, and how it compares to other orectolobiforms in light of its specialization as a plankton-feeder. Brain size and overall brain organization was assessed in two specimens of R. typus in relation to both phylogeny and ecology, using magnetic resonance imaging (MRI). In comparison to over 60 other chondrichthyan species, R. typus demonstrated a relatively small brain for its body size (expressed in terms of encephalization quotients and residuals), similar to the lamniforms Carcharodon carcharias, Cetorhinus maximus, and Carcharias taurus. R. typus possessed a relatively small telencephalon with some development of the dorsal pallium, which was suggestive of moderate social behavior, in addition to a relatively large diencephalon and a relatively reduced mesencephalon. The most notable characteristic of the brain of Rhincodon was a large and highly foliated cerebellum, one of the largest cerebellums within the chondrichthyan clade. Early development of the brain was qualitatively assessed using an in situ MRI scan of the brain and chondrocranium of a neonate specimen of R. typus. There was evidence that folding of the cerebellar corpus appeared in early development, although the depth and number of folds might vary ontogenetically in this species. Hierarchical cluster analysis and multidimensional scaling ordinations showed evidence of convergent evolution with the basking shark, Cetorhinus maximus, another large-bodied filter feeding elasmobranch, supporting the claim that organization of the brain is more similar in species with analogous but independently evolved lifestyles than those that share taxonomic classification. |
format |
Article in Journal/Newspaper |
author |
Yopak, Kara E. Frank, Lawrence R. |
spellingShingle |
Yopak, Kara E. Frank, Lawrence R. Brain Size and Brain Organization of the Whale Shark, Rhincodon typus, Using Magnetic Resonance Imaging |
author_facet |
Yopak, Kara E. Frank, Lawrence R. |
author_sort |
Yopak, Kara E. |
title |
Brain Size and Brain Organization of the Whale Shark, Rhincodon typus, Using Magnetic Resonance Imaging |
title_short |
Brain Size and Brain Organization of the Whale Shark, Rhincodon typus, Using Magnetic Resonance Imaging |
title_full |
Brain Size and Brain Organization of the Whale Shark, Rhincodon typus, Using Magnetic Resonance Imaging |
title_fullStr |
Brain Size and Brain Organization of the Whale Shark, Rhincodon typus, Using Magnetic Resonance Imaging |
title_full_unstemmed |
Brain Size and Brain Organization of the Whale Shark, Rhincodon typus, Using Magnetic Resonance Imaging |
title_sort |
brain size and brain organization of the whale shark, rhincodon typus, using magnetic resonance imaging |
publisher |
S. Karger AG |
publishDate |
2009 |
url |
http://dx.doi.org/10.1159/000235962 https://www.karger.com/Article/Pdf/235962 |
genre |
Cetorhinus maximus |
genre_facet |
Cetorhinus maximus |
op_source |
Brain, Behavior and Evolution volume 74, issue 2, page 121-142 ISSN 0006-8977 1421-9743 |
op_rights |
https://www.karger.com/Services/SiteLicenses https://www.karger.com/Services/SiteLicenses |
op_doi |
https://doi.org/10.1159/000235962 |
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Brain, Behavior and Evolution |
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74 |
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2 |
container_start_page |
121 |
op_container_end_page |
142 |
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1811637510884818944 |