Tadasu Yamada | National Museum of Nature and Science (original) (raw)
Papers by Tadasu Yamada
Frontiers in Marine Science, 2019
Mammal Study
Striped dolphins (Stenella coeruleoalba) mass-stranded on 26 April 2013 at Minamisatsuma, Kagoshi... more Striped dolphins (Stenella coeruleoalba) mass-stranded on 26 April 2013 at Minamisatsuma, Kagoshima Prefecture, in southern Japan (East China Sea). The diet of the mass-stranded striped dolphins was investigated to reveal their foraging pattern through analyses of the stomach contents and stable isotopes in muscle. Of 26 stomachs sampled, 25 contained hard parts of prey animals; no fleshy remains were found in any of the stomachs. The identified prey species represented four cephalopod families: Loliginidae, Onychoteuthidae, Histioteuthidae, and Ommastrephidae. Among these, ommastrephids had the highest abundance (42.4%) and frequency of occurrence (69.2%). A chi-square test revealed that the prey species consumed did not significantly differ between male and female dolphins, although deeper-water squids (Onychoteuthidae and Histioteuthidae) appeared only in the stomachs of females. The values of 13 C ranged from −20.4 to −17.0‰ (mean ± SD: −18.2 ± 0.9‰), and values of 15 N ranged from 10.2 to 12.5‰ (10.8 ± 0.5‰), with a significant difference in 15 N between sexes (p < 0.05).
Publisher Summary Omura's whale is a medium-sized baleen whale found in lower latitude Indo-P... more Publisher Summary Omura's whale is a medium-sized baleen whale found in lower latitude Indo-Pacific waters of both the hemispheres. The body length of the species is about 10–12 m. External proportions of the body are similar to those of the Bryde's whales and sei whale. Absence of lateral ridges on the dorsal surface of the head is the most diagnostic characteristic for distinguishing it from the Bryde's whales. The lateral contour of the upper jaw is convex as in the blue whale. The ventral pleats extend as far as around the umbilicus, separating it from the sei whale. Omura's whale is distinctly counter-shaded, basically black above and off-white below. The dark portion of the color pattern is lighter than in the fin whale. The configuration of the vertex is also unique; the posterior end of the ascending process of the maxilla widens and becomes squarish and the posterior end of the premaxilla becomes thin and sinks between the nasal and the maxilla. A narrow area of the frontal is exposed between the nasals and the occipital shield. Nothing is known of the behavior and physiology of this whale.
Japan Cetology, 2009
During the process of the recent description of a new balaenopterid species, Omura's whale, Balae... more During the process of the recent description of a new balaenopterid species, Omura's whale, Balaenoptera omurai Wada, Oishi et Yamada, 2003, the authors proposed to differentiate the so-called "Bryde's whale", then defined collectively as Balaenoptera edeni Anderson, 1878/9 into Eden's whale, B. edeni and Bryde's whale (sensu stricto), Balaenoptera brydei Olsen, 1913. In their project investigating middle sized balaenopterid whales in Taiwan and Thailand, the authors found many specimens that could be classified into the three species. In addition to the characteristics of the vertex of the skull, the morphology of the lateral surface of the braincase around the alisphenoid has been established as a means of distinguishing among the three species as the specimens for comparison has increased. The balaenopterid specimens, formerly identified as the so-called "Bryde's whale", B. edeni which are preserved in the Wakayama Prefectural Museum of Natural History (Wakayama specimen) and Kitsuki City Library in Oita Prefecture (Kitsuki specimen), are now judged in fact to be Eden's whales, B. edeni based on the comparison of the vertex and alisphenoid morphology of the formerly described specimens, including the holotype of B. edeni.
Nihon setoroji kenkyu, 2020
We received the whale stranding records from Matsumae-cho, Hokkaido, for the period 1992-2002 in ... more We received the whale stranding records from Matsumae-cho, Hokkaido, for the period 1992-2002 in 2013. Species and sex were identified as far as possible from the photographs provided. As a result of the identification, 11 individuals (SNH13901 to SNH13911) were obtained in 11 cases: nine individuals of Stejneger's beaked whales, one Baird's beaked whale, and one minke whale.
Nihon setoroji kenkyu, 2009
During mid-April to early May in 2005, a gray whale appeared in Tokyo bay. On May 11, the animal ... more During mid-April to early May in 2005, a gray whale appeared in Tokyo bay. On May 11, the animal was finally caught in a set net 1km off Koura, Minamiboso city at the entrance of Tokyo bay (Institute of Cetacean Research Stranding Database (ICRSD) M-768). The animal was confirmed as a 7.81 m female at the necropsy. We observed the animal on three occasions in the areas off Sodegaura, Narashino, and between Yokosuka and Yokohama. In those waters, the animal came into coastal shallow waters, 20 m to 100 m in Sodegaura, 10 m to 100 m in Narashino, and 100 m to 1,400 m (depth between 11 m and 18 m) from the coasts between Yokosuka and Yokohama. The anima1 presumably tried to feed both in the Sodegaura and Narashino areas, and simply cruised between Yokosuka and Yokohama. It was suspected that the animal strayed into Tokyo bay on the way up to the feeding grounds in the north. It is suspected that there are possibilities of the gray whale prefers for feeding on the muddy bottom, and has instinctive tendency to travel northward.
Nihon setoroji kenkyu, 2014
Mammal Study, May 8, 2018
In mammals, the recurrent laryngeal nerve (RLN) loops around the ligamentum arteriosum on the lef... more In mammals, the recurrent laryngeal nerve (RLN) loops around the ligamentum arteriosum on the left side and around the subclavian artery on the right side. It is generally considered that such an asymmetric arrangement of the right and left RLN is brought about by a transformation of the aortic arches at an early stage of embryonic development. We have dissected rough-toothed dolphins and Pacific white-sided dolphins in this study. In both species, the right RLN hooked around the costocervical trunk, while the left RLN hooked around the ligamentum arteriosum. The external carotid artery, the internal carotid artery, the subclavian artery, and the costocervical trunk arose radially from the brachiocephalic trunk on the right side. The left costocervical trunk arose directly from the aortic arch. The right and left subclavian arteries ran ventral to the subclavian vein and the vagus nerve, in a similar manner to the secondary subclavian arteries in birds. These findings suggest that the replacement of the primary (or dorsal) subclavian artery by the secondary (or ventral) subclavian artery might occur at a certain embryonic stage in dolphins as well.
Journal of Veterinary Medical Science, 2019
Two stranded whales were found dead on the coast of Jeju, South Korea. Based on the outer appeara... more Two stranded whales were found dead on the coast of Jeju, South Korea. Based on the outer appearance and autopsy findings, one was determined to be an adult and the other a calf. The carcasses were dissected for species identification and pathological examination. A genetic analysis was performed, and the morphological characteristics of the skull observed. Then, 448 bp of the 5′ half of the mitochondrial (mt) DNA control region and 413 bp of the mtDNA cytochrome b gene were sequenced. A BLAST search revealed that the whales were ginkgo-toothed beaked whales (Mesoplodon ginkgodens). Morphological comparison of the adult skull with the holotype specimen confirmed the result. This is the first record of a stranded ginkgo-toothed beaked whale in Korea.
Genetics and molecular biology
The genus Mesoplodon (Cetacea: Odontoceti: Ziphiidae) is one of the few cetacean genera with the ... more The genus Mesoplodon (Cetacea: Odontoceti: Ziphiidae) is one of the few cetacean genera with the karyotype 2n = 42. The 2n = 42 karyotype of M. europaeus and M. carlhubbsi is largely consistent with the general cetacean karyotype 2n = 44, although other 2n = 42 karyotypes do not exhibit clear homologies with the general cetacean karyotype. Therefore, the chromosomes of Mesoplodon species may be the key to understanding cetacean karyological evolution. In the present study, the male karyotypes of M. stejnegeri and M. carlhubbsi were examined. In both species, the diploid number of the male karyotype was 42. Both species had the following characteristics: 1) a huge subtelocentric X chromosome with a large C-block; 2) a small metacentric Y chromosome; 3) nucleolus organizer regions (NORs) in the terminal regions of a large autosome and one or two small metacentric autosomes; 4) small metacentric autosomes; 5) large submetacentric and subtelocentric autosomes; 6) less accumulated C-hete...
Marine environmental research, Jan 5, 2016
This study investigated the accumulation of polybrominated diphenyl ethers (PBDEs) and their hydr... more This study investigated the accumulation of polybrominated diphenyl ethers (PBDEs) and their hydroxylated and methoxylated analogues (OH-PBDEs and MeO-PBDEs) in the blood of harbor porpoises, Dall's porpoises, and finless porpoises stranded or bycaught in Japanese coastal waters and in the North Pacific Ocean. Moreover, we suggested the origins of these contaminants and the factors affecting their pattern of accumulation. Levels of PBDEs in Dall's porpoises were one order of magnitude greater than those in the other species. OH-PBDE and MeO-PBDE levels were comparable to those of PBDEs. However, no correlation was found between the levels of OH-PBDEs and PBDEs, whereas a strong correlation was found between that of OH-PBDEs and MeO-PBDEs (p < 0.001). 6OH-BDE47, reported compound biosynthesized by marine low-trophic level organisms, was the dominant congener. These results suggest that PBDEs found in these porpoise species derive from flame retardants, but OH-PBDEs and MeO...
Kaibogaku zasshi. Journal of anatomy, 1986
Cells Tissues Organs, 1991
ABSTRACT
TRENDS IN THE SCIENCES, 2010
Frontiers in Marine Science, 2019
Mammal Study
Striped dolphins (Stenella coeruleoalba) mass-stranded on 26 April 2013 at Minamisatsuma, Kagoshi... more Striped dolphins (Stenella coeruleoalba) mass-stranded on 26 April 2013 at Minamisatsuma, Kagoshima Prefecture, in southern Japan (East China Sea). The diet of the mass-stranded striped dolphins was investigated to reveal their foraging pattern through analyses of the stomach contents and stable isotopes in muscle. Of 26 stomachs sampled, 25 contained hard parts of prey animals; no fleshy remains were found in any of the stomachs. The identified prey species represented four cephalopod families: Loliginidae, Onychoteuthidae, Histioteuthidae, and Ommastrephidae. Among these, ommastrephids had the highest abundance (42.4%) and frequency of occurrence (69.2%). A chi-square test revealed that the prey species consumed did not significantly differ between male and female dolphins, although deeper-water squids (Onychoteuthidae and Histioteuthidae) appeared only in the stomachs of females. The values of 13 C ranged from −20.4 to −17.0‰ (mean ± SD: −18.2 ± 0.9‰), and values of 15 N ranged from 10.2 to 12.5‰ (10.8 ± 0.5‰), with a significant difference in 15 N between sexes (p < 0.05).
Publisher Summary Omura's whale is a medium-sized baleen whale found in lower latitude Indo-P... more Publisher Summary Omura's whale is a medium-sized baleen whale found in lower latitude Indo-Pacific waters of both the hemispheres. The body length of the species is about 10–12 m. External proportions of the body are similar to those of the Bryde's whales and sei whale. Absence of lateral ridges on the dorsal surface of the head is the most diagnostic characteristic for distinguishing it from the Bryde's whales. The lateral contour of the upper jaw is convex as in the blue whale. The ventral pleats extend as far as around the umbilicus, separating it from the sei whale. Omura's whale is distinctly counter-shaded, basically black above and off-white below. The dark portion of the color pattern is lighter than in the fin whale. The configuration of the vertex is also unique; the posterior end of the ascending process of the maxilla widens and becomes squarish and the posterior end of the premaxilla becomes thin and sinks between the nasal and the maxilla. A narrow area of the frontal is exposed between the nasals and the occipital shield. Nothing is known of the behavior and physiology of this whale.
Japan Cetology, 2009
During the process of the recent description of a new balaenopterid species, Omura's whale, Balae... more During the process of the recent description of a new balaenopterid species, Omura's whale, Balaenoptera omurai Wada, Oishi et Yamada, 2003, the authors proposed to differentiate the so-called "Bryde's whale", then defined collectively as Balaenoptera edeni Anderson, 1878/9 into Eden's whale, B. edeni and Bryde's whale (sensu stricto), Balaenoptera brydei Olsen, 1913. In their project investigating middle sized balaenopterid whales in Taiwan and Thailand, the authors found many specimens that could be classified into the three species. In addition to the characteristics of the vertex of the skull, the morphology of the lateral surface of the braincase around the alisphenoid has been established as a means of distinguishing among the three species as the specimens for comparison has increased. The balaenopterid specimens, formerly identified as the so-called "Bryde's whale", B. edeni which are preserved in the Wakayama Prefectural Museum of Natural History (Wakayama specimen) and Kitsuki City Library in Oita Prefecture (Kitsuki specimen), are now judged in fact to be Eden's whales, B. edeni based on the comparison of the vertex and alisphenoid morphology of the formerly described specimens, including the holotype of B. edeni.
Nihon setoroji kenkyu, 2020
We received the whale stranding records from Matsumae-cho, Hokkaido, for the period 1992-2002 in ... more We received the whale stranding records from Matsumae-cho, Hokkaido, for the period 1992-2002 in 2013. Species and sex were identified as far as possible from the photographs provided. As a result of the identification, 11 individuals (SNH13901 to SNH13911) were obtained in 11 cases: nine individuals of Stejneger's beaked whales, one Baird's beaked whale, and one minke whale.
Nihon setoroji kenkyu, 2009
During mid-April to early May in 2005, a gray whale appeared in Tokyo bay. On May 11, the animal ... more During mid-April to early May in 2005, a gray whale appeared in Tokyo bay. On May 11, the animal was finally caught in a set net 1km off Koura, Minamiboso city at the entrance of Tokyo bay (Institute of Cetacean Research Stranding Database (ICRSD) M-768). The animal was confirmed as a 7.81 m female at the necropsy. We observed the animal on three occasions in the areas off Sodegaura, Narashino, and between Yokosuka and Yokohama. In those waters, the animal came into coastal shallow waters, 20 m to 100 m in Sodegaura, 10 m to 100 m in Narashino, and 100 m to 1,400 m (depth between 11 m and 18 m) from the coasts between Yokosuka and Yokohama. The anima1 presumably tried to feed both in the Sodegaura and Narashino areas, and simply cruised between Yokosuka and Yokohama. It was suspected that the animal strayed into Tokyo bay on the way up to the feeding grounds in the north. It is suspected that there are possibilities of the gray whale prefers for feeding on the muddy bottom, and has instinctive tendency to travel northward.
Nihon setoroji kenkyu, 2014
Mammal Study, May 8, 2018
In mammals, the recurrent laryngeal nerve (RLN) loops around the ligamentum arteriosum on the lef... more In mammals, the recurrent laryngeal nerve (RLN) loops around the ligamentum arteriosum on the left side and around the subclavian artery on the right side. It is generally considered that such an asymmetric arrangement of the right and left RLN is brought about by a transformation of the aortic arches at an early stage of embryonic development. We have dissected rough-toothed dolphins and Pacific white-sided dolphins in this study. In both species, the right RLN hooked around the costocervical trunk, while the left RLN hooked around the ligamentum arteriosum. The external carotid artery, the internal carotid artery, the subclavian artery, and the costocervical trunk arose radially from the brachiocephalic trunk on the right side. The left costocervical trunk arose directly from the aortic arch. The right and left subclavian arteries ran ventral to the subclavian vein and the vagus nerve, in a similar manner to the secondary subclavian arteries in birds. These findings suggest that the replacement of the primary (or dorsal) subclavian artery by the secondary (or ventral) subclavian artery might occur at a certain embryonic stage in dolphins as well.
Journal of Veterinary Medical Science, 2019
Two stranded whales were found dead on the coast of Jeju, South Korea. Based on the outer appeara... more Two stranded whales were found dead on the coast of Jeju, South Korea. Based on the outer appearance and autopsy findings, one was determined to be an adult and the other a calf. The carcasses were dissected for species identification and pathological examination. A genetic analysis was performed, and the morphological characteristics of the skull observed. Then, 448 bp of the 5′ half of the mitochondrial (mt) DNA control region and 413 bp of the mtDNA cytochrome b gene were sequenced. A BLAST search revealed that the whales were ginkgo-toothed beaked whales (Mesoplodon ginkgodens). Morphological comparison of the adult skull with the holotype specimen confirmed the result. This is the first record of a stranded ginkgo-toothed beaked whale in Korea.
Genetics and molecular biology
The genus Mesoplodon (Cetacea: Odontoceti: Ziphiidae) is one of the few cetacean genera with the ... more The genus Mesoplodon (Cetacea: Odontoceti: Ziphiidae) is one of the few cetacean genera with the karyotype 2n = 42. The 2n = 42 karyotype of M. europaeus and M. carlhubbsi is largely consistent with the general cetacean karyotype 2n = 44, although other 2n = 42 karyotypes do not exhibit clear homologies with the general cetacean karyotype. Therefore, the chromosomes of Mesoplodon species may be the key to understanding cetacean karyological evolution. In the present study, the male karyotypes of M. stejnegeri and M. carlhubbsi were examined. In both species, the diploid number of the male karyotype was 42. Both species had the following characteristics: 1) a huge subtelocentric X chromosome with a large C-block; 2) a small metacentric Y chromosome; 3) nucleolus organizer regions (NORs) in the terminal regions of a large autosome and one or two small metacentric autosomes; 4) small metacentric autosomes; 5) large submetacentric and subtelocentric autosomes; 6) less accumulated C-hete...
Marine environmental research, Jan 5, 2016
This study investigated the accumulation of polybrominated diphenyl ethers (PBDEs) and their hydr... more This study investigated the accumulation of polybrominated diphenyl ethers (PBDEs) and their hydroxylated and methoxylated analogues (OH-PBDEs and MeO-PBDEs) in the blood of harbor porpoises, Dall's porpoises, and finless porpoises stranded or bycaught in Japanese coastal waters and in the North Pacific Ocean. Moreover, we suggested the origins of these contaminants and the factors affecting their pattern of accumulation. Levels of PBDEs in Dall's porpoises were one order of magnitude greater than those in the other species. OH-PBDE and MeO-PBDE levels were comparable to those of PBDEs. However, no correlation was found between the levels of OH-PBDEs and PBDEs, whereas a strong correlation was found between that of OH-PBDEs and MeO-PBDEs (p < 0.001). 6OH-BDE47, reported compound biosynthesized by marine low-trophic level organisms, was the dominant congener. These results suggest that PBDEs found in these porpoise species derive from flame retardants, but OH-PBDEs and MeO...
Kaibogaku zasshi. Journal of anatomy, 1986
Cells Tissues Organs, 1991
ABSTRACT
TRENDS IN THE SCIENCES, 2010