Published Papers - Ikeda Yuzuru

Erratum to: Structure of the seminal receptacle and sperm storage in the Japanese pygmy squid: Structure of the seminal receptacle of pygmy squids (Journal of Zoology, (2010), 282, 3, (151-156), 10.1111/j.1469-7998.2010.00733.x)

N. Sato, T. Kasugai, Y. Ikeda, H. Munehara

Journal of Zoology ( Blackwell Publishing Ltd )  282 ( 3 ) 151 - 156   2018.02 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

　View Summary

To examine the mechanism of sperm storage in Idiosepius paradoxus, here we describe aspects of the mating behavior of I. paradoxus and the morphology of the spermatozoa and the seminal receptacle after copulation. The seminal receptacle is located in the ventral portion of the buccal membrane surrounding the buccal mass, and opens inside the buccal membrane. It branches into approximately six sacs, similar in appearance to a bunch of bananas, and its wall consists of cuboidal ciliated epithelial cells (with oval nuclei) surrounded by a connective tissue. Multiple vacuoles are distributed in the bottom region of each sac. These histological and morphological characteristics differ from previous reports for loliginid squids and cuttlefish. In all except one receptacle observed in this study, sperm were stored near the bottom of each sac, and each sperm was facing the sac bottom. We observed spermatozoa in the entrance of the seminal receptacle in only one squid. These results suggest that spermatozoa were actively moving, and that sperm actively swam to the seminal receptacle. The volume of sperm in the seminal receptacles of the squid that had copulated eight times was the same as that in the squid that had copulated 29 times, which suggests that the seminal receptacle was filled after approximately eight copulation events. A squid that had copulated nine times retained a significant number of sperm in the seminal receptacle after spawning, suggesting that all of the sperm in the receptacle was not depleted after one spawning event. © 2010 The Authors. Journal of Zoology © 2010 The Zoological Society of London.

• Access this article

  DOI

Correction to: Unique arm-flapping behavior of the pharaoh cuttlefish, <i>Sepia pharaonis</i>: putative mimicry of a hermit crab.

Okamoto K, Yasumuro H, Mori A, Ikeda Y

Journal of ethology ( Journal of Ethology )  36 ( 2 ) 219 - 219   2018 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

　View Summary

The article, “Unique arm-flapping behavior of the pharaoh cuttlefish, Sepia pharaonis: putative mimicry of a hermit crab”, written by Kohei Okamoto, Haruhiko Yasumuro.

• Access this article

  DOI
• Search related information
  PubMed

A catalog of the chromatic, postural, and locomotor behaviors of the pharaoh cuttlefish (Sepia pharaonis) from Okinawa Island, Japan

Ryuta Nakajima, Yuzuru Ikeda

MARINE BIODIVERSITY ( SPRINGER HEIDELBERG )  47 ( 3 ) 735 - 753   2017.09 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

　View Summary

Coleoid cephalopods such as cuttlefishes, squids, and octopods are able to produce a diverse array of visual expressions that are used for mimesis and inter- and intraspecific communication. They achieve this by intricately combining several neurally controlled behaviors, which include chromatic, textural, postural, and locomotor components. To understand this diverse range of body patterns, it is necessary to develop an accurate and extensive catalog of them, which can then be used as a tool for future behavioral monitoring and quantitative analyses, as well as for the identification of morphologically identical sub-species. In this study, a catalog of the chromatic, postural, and locomotor behaviors was produced for the pharaoh cuttlefish (Sepia pharaonis) from coastal waters of Okinawa Island, Japan. Data were collected from aquacultured animals using egg masses sampled from around the island and hatched in aquaria during 2010, 2011, 2012, and 2014. In total, 53 chromatic, four supplementary chromatic conditions, three textural, 11 postural, and nine locomotor components were identified and described in detail. Many of the described components are similar to previously described body patterns of Sepia officinalis. However, there are notable differences between the two species, which may indicate that they use body patterns in different ways for cryptic behavior and inter- and intraspecific communication.

• Access this article

  DOI

Unique arm-flapping behavior of the pharaoh cuttlefish, <i>Sepia pharaonis</i>: putative mimicry of a hermit crab.

Okamoto K, Yasumuro H, Mori A, Ikeda Y

Journal of ethology ( SPRINGER JAPAN KK )  35 ( 3 ) 307 - 311   2017 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

　View Summary

Cephalopods are able to control their arms sophisticatedly and use them for various behaviors, such as camouflage, startling predators and hunting prey. Here, we report a previously undescribed arm-flapping behavior of the pharaoh cuttlefish, Sepia pharaonis, observed in captivity. S. pharaonis raised the first pair of arms and wrinkled the parts near the distal end, where the skin color was darkened. Additionally, S. pharaonis spread the second and third pairs of arms and bent them as if they were jointed, and flapped the distal ends. S. pharaonis showed this behavior in two different situations: after being introduced into a large space, and during hunting. We discuss the putative functions of this behavior, including possible mimicry of a hermit crab, considering the situations in which the behavior was observed.

• Access this article

  DOI
• Search related information
  PubMed

Salt soluble without jelly-like component from the oviducal gland induces chorionic expansion in the ova of the Japanese common squid Todarodes pacificus

Kohsuke Adachi, Mao Yabumoto, Haekyun Yoo, Katsuji Morioka, Yuzuru Ikeda, Yukio Ueta, Yasunori Sakurai

INVERTEBRATE REPRODUCTION & DEVELOPMENT ( TAYLOR & FRANCIS LTD )  60 ( 4 ) 281 - 289   2016.12 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

　View Summary

In vitro fertilization of squid requires the jelly substance found in the female oviducal gland; yet, the active component of this substance that facilitates fertilization remains unknown. Here, we used biochemical methods to separate the jelly substance of Todarodes pacificus (Oegopsida) and Sepioteuthis lessoniana (Myopsida family) into four fractions; specifically, two water soluble fractions (Molecular weight&gt;10,000 and&lt;10,000), one salt soluble fraction, and one insoluble fraction. The salt soluble fraction of T. pacificus induced chorionic expansion (perivitelline space formation), which precedes the normal embryonic development of ova. In contrast, the salt soluble fraction of S. lessoniana elicited insufficient expansion of the ova, only producing embryos with high abnormality rates. These results suggest that the salt soluble component(s) (not the jelly-like substances) in the oviducal gland induce chorionic expansion and hatching in Oegopsida, and that these components may be similar in Myopsida.

• Access this article

  DOI

Environmental Enrichment Accelerates the Ontogeny of Cryptic Behavior in Pharaoh Cuttlefish (Sepia pharaonis).

Yasumuro H, Ikeda Y

Zoological science ( ZOOLOGICAL SOC JAPAN )  33 ( 3 ) 255 - 65   2016.06 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

　View Summary

We examined effect of environmental enrichment on cuttlefish, the most neutrally advanced invertebrate, to compare species variation of genetic and environmental influences. Cuttlefish were reared from seven to 117 days in one of three environments, namely, "poor" (artificial bottom without objects), "standard" (sandy bottom), and "enriched" (sandy bottom with objects). In Experiment 1, we explored whether enrichment affects the exhibition of crypsis in the cuttlefish. The cuttlefish in the standard and enriched environments spent most of their time at the bottom, exhibiting the mottled or disruptive pattern starting at 27 days of age. On the contrary, those in the poor environment exhibited uniform pattern starting at 87 days of age. Additionally, they repeatedly attempted to dig from 27 to 87 days of age, and moved around by hovering from 77 to 117 days of age. In Experiment 2, we exposed the cuttlefish to six novel substrates every other month after 53 days of age to verify whether enrichment actually affected the maturation of cryptic ability. Cuttlefish from the poor environment tended not to dig into white sandy bottom at 53-55 days of age. Additionally, they did not clearly exhibit appropriate body patterns in response to the six substrates compared to those from the other two environments at 81-83 days of age. However, at 113-115 days of age, most cuttlefish from the three environments exhibited similar cryptic behaviors in response to novel substrates. We conclude that physical enrichment promotes crypsis and accelerates the maturation of this ability in cuttlefish.

• Access this article

  DOI
• Search related information
  PubMed

Effects of Visual Cues of a Moving Model Predator on Body Patterns in Cuttlefish Sepia pharaonis.

Okamoto K, Mori A, Ikeda Y

Zoological science ( ZOOLOGICAL SOC JAPAN )  32 ( 4 ) 336 - 44   2015.08 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

　View Summary

We examined the effects of predator-prey distance (PPD) and trajectory of the predator on the body patterns that the pharaoh cuttlefish, Sepia pharaonis, shows in response to a predator. A model predator moving in three different trajectories was presented to the cuttlefish: T1, approached the cuttlefish but bypassed above; T2, approached directly toward the cuttlefish; T3, bypassed the cuttlefish both vertically and horizontally. We divided the body patterns that the cuttlefish expressed into seven categories, i.e., "uniform light", "disruptive", "center circle", "dark square", "vertical stripe", "all dark"and "eyespots". In T1, the number of individuals that showed "dark square"increased as the model approached the cuttlefish, whereas the number of individuals that showed "disruptive" decreased. In T2, the number of individuals that showed "all dark"and "eyespots"increased as the model approached the cuttlefish. In T3, the number of individuals that showed "dark square" and "vertical stripe"increased as the model approached the cuttlefish, and it tended to decrease as the model receded from the cuttlefish. These results demonstrate that S. pharaonis changes its body patterns according to PPD and the trajectory of the predator, which would affect predation risk and/or predator perception.

• Access this article

  DOI
• Search related information
  PubMed

Cuttlefish can school in the field

Haruhiko Yasumuro, Shogo Nakatsuru, Yuzuru Ikeda

MARINE BIOLOGY ( SPRINGER HEIDELBERG )  162 ( 4 ) 763 - 771   2015.04 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

　View Summary

Cuttlefish (Sepiidae) are usually solitary in nature, but we have found evidence that the broadclub cuttlefish (Sepia latimanus) forms schools. S. latimanus groups of various sizes were observed for 145 min in Okinawa, Japan. The groups were comprised of 2-9 members that were usually of similar body sizes. The groups continuously changed shape, forming either clusters or lines. The groups were regarded as schools and had characteristic structures such as synchronized and polarized swimming with similar distances apart from each other (similar to 4.0 mantle length), and swam in parallel (under 20A degrees or over 110A degrees in angle) to their nearest neighbours, regardless of the numbers of members in the group. Small members sometimes followed larger members within the school. These characteristics were similar to those observed in schools of Teuthoidea squid. Schools comprising large numbers of members frequently exhibited hunting behaviour for small crustaceans and fish. This is the first observation of schooling behaviour in wild Sepiidae.

• Access this article

  DOI

6. 頭足類学という可能性

池田 譲

日本水産学会誌 ( 公益社団法人 日本水産学会 )  81 ( 1 ) 139 - 139   2015

Type of publication: Research paper (research society, symposium materials, etc.)

• Access this article

  DOI

はじめに

池田 譲, 宮崎 多恵子

日本水産学会誌 ( 公益社団法人 日本水産学会 )  81 ( 1 ) 133 - 133   2015 [ Peer Review Accepted ]

Type of publication: Research paper (research society, symposium materials, etc.)

• Access this article

  DOI

Notes on an exhausted Japanese common squid, Todarodes pacificus (Cephalopoda: Ommastrephidae), with an unusually short arm

Kidokoro　Hideaki,Uji　Ryosuke

No.77 (2004/3) ( 琉球大学理学部 )  ( 77 ) 143 - 148   2009.08

Type of publication: Research paper (bulletin of university, research institution)

　View Summary

A Japanese common squid, Todarodes pacificus with an unusually short left fourth arm was captured from the Sea of Japan on October 1996. This specimen was a mature male (mantle length 216 mm, body weight 186 g) ""Kawa-ika"" squid that seemed to be nearing the end of its reproductive life. About two-thirds of the left fourth arm of this individual was lost and the surface of the arm's tip was completely covered with skin. This short arm was either caused by i) malformation or ii) accidental loss of the tip, followed by regeneration. Arm regeneration is common in cephalopods, and the left fourth arm of the present specimen was very similar to the regenerating arms of other cephalopods. Therefore, the arm of the present specimen may be regenerating. Since T. pacificus is a terminal spawner, this specimen indicates that regeneration can still occur even during later phases of the life cycle. （管理者追加）リポジトリ登録情報を移行しました。確認のうえ、加除修正をしてください。

• Access this article

  DOI

Reproduction and life span of the oval squid Sepioteuthis lessoniana (Cephalopoda: Loliginidae): comparison between laboratory-cultured and wild-caught squid

Y. Ikeda, Y. Ueta, F. E. Anderson and G. Matsumoto

JMBA2-Biodiversity Records ( その他の出版社 )    2008.08 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

• Access this article

  DOI

Low genetic diversity of oval squid Sepioteuthis cf. lessoniana (Cephalopoda: Loliginidae), in Japanese waters inferred from a mitochondrial DND non-coding region

M. Aoki, H. Imai, T. Naruse, Y. Ikeda

Pacific Science ( その他の出版社 )  62   403 - 411   2008.03 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

Mirror image reactions in the oval squid Sepioteuthis lessoniana

Ikeda, Y. and G. Matsumoto

Fisheries Science ( その他の出版社 )  73   1401 - 1403   2007.12 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

• Access this article

  DOI

Egg brooding behavior and embryonic development of Octopus laqueus (Cephalopoda: Octopodidae).

Kaneko, N., Osima, Y., and Ikeda, Y.

Molluscan Research ( その他の出版社 )  26   113 - 117   2006.01 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

Rearing of squid hatchlings, Heterololigo bleekeri (Keferstein 1866) up to 2 months in a closed seawater system.

Ikeda Y., Sakurazawa I., Ito K., Sakurai Y., Matsumoto G.

Aquaculture Research ( その他の出版社 )  36   409 - 412   2005.01 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

• Access this article

  DOI

Transport of the oval squid Sepioteuthis lessoniana Feussac, 1831 in Lesson 1830-1831 (Cephalopoda: Loliginidae) for up to 24 hours and subsequent transfer to an aquarium

Ikeda.Y,et al

Fisheries Sci ( その他の出版社 )  ( 70 ) 21 - 27   2004.03

Type of publication: Research paper (other science council materials etc.)

Feeding, external digestion in Japanese pygmy squid, Idiosepius paradoxus (Cephalopoda：Idiosepiidae)

Kasugai.T,et al

J. Mollus. St. ( その他の出版社 )  70   231 - 236   2004.03 [ Peer Review Accepted ]

Type of publication: Research paper (other science council materials etc.)

Note on fertilizing capacity of spermatozoa stored in spermatangium: a possible extra sperm storage site in the Japanese common squid Todarodes pacificus

Ikeda.Y,Sakurai.Y

Suisanzoshoku ( その他の出版社 )  51   101 - 102   2004.01 [ Peer Review Accepted ]

Type of publication: Research paper (other science council materials etc.)

Notes on an exhausted Japanese common squid, Todarodes pacificus (Cephalopoda: Ommastrephidae), with an unusually short arm.

Ikeda Y., Uji R., Kidokoro H.

Bulletin of the Faculty of Science, University of the Rykyus ( その他の出版社 )  77   143 - 147   2004.01 [ Peer Review Accepted ]

Type of publication: Research paper (bulletin of university, research institution)