Talk:Shark Development

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Cite this page: Hill, M.A. (2019, December 13) Embryology Shark Development. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Talk:Shark_Development

2019

2018

Oviparous elasmobranch development inside the egg case in 7 key stages

PLoS One. 2018 Nov 6;13(11):e0206984. doi: 10.1371/journal.pone.0206984. eCollection 2018.

Musa SM1,2, Czachur MV1, Shiels HA1. Author information Abstract Embryological stages of oviparous elasmobranch during development can be difficult to identify, requiring magnification and/or fixation of an anaesthetized embryo. These restrictions are poorly suited for monitoring the development of living elasmobranchs inside their egg cases. There are two major aims of this study. The first was to observe elasmobranch embryonic development non-invasively and produce a non-invasive developmental key for identifying the life stages for an elasmobranch inside the egg case. To this end, 7 key developmental stages were identified for the greater spotted catshark, Scyliorhinus stellaris, and are provided here with diagrams from multiple perspectives to demonstrate the key features of each stage. The physiological and ecological relevance of each stage are discussed in terms of structure and function for embryonic survival in the harsh intertidal zone. Also discussed is the importance of the egg case membrane and the protective embryonic jelly. The second aim of the study was to understand the applicability of the 7 developmental stages from S. stellaris to other oviparous elasmobranchs. Thus, changes in embryonic body size and egg yolk volume at each stage were measured and compared with those of the closely related, lesser spotted catshark, Scyliorhinus canicula. We find nearly identical growth patterns and yolk consumption patterns in both species across the 7 developmental stages. Thus, although the 7 developmental stages have been constructed in reference to the greater spotted catshark, we suggest that it can be applied to other oviparous elasmobranch species with only minor modification.

PMID: 30399186 PMCID: PMC6219803 DOI: 10.1371/journal.pone.0206984


A staging table for the embryonic development of the brownbanded bamboo shark (Chiloscyllium punctatum)

Onimaru K1, Motone F1,2, Kiyatake I3, Nishida K3, Kuraku S1. Author information Abstract BACKGROUND: Studying cartilaginous fishes (chondrichthyans) has helped us understand vertebrate evolution and diversity. However, resources such as genome sequences, embryos, and detailed staging tables are limited for species within this clade. To overcome these limitations, we have focused on a species, the brownbanded bamboo shark (Chiloscyllium punctatum), which is a relatively common aquarium species that lays eggs continuously throughout the year. In addition, because of its relatively small genome size, this species is promising for molecular studies.

RESULTS: To enhance biological studies of cartilaginous fishes, we establish a normal staging table for the embryonic development of the brownbanded bamboo shark. Bamboo shark embryos take around 118 days to reach the hatching period at 25°C, which is approximately 1.5 times as fast as the small-spotted catshark (Scyliorhinus canicula) takes. Our staging table divides the embryonic period into 38 stages. Furthermore, we found culture conditions that allow early embryos to grow in partially opened egg cases.

CONCLUSIONS: In addition to the embryonic staging table, we show that bamboo shark embryos exhibit relatively fast embryonic growth and are amenable to culture, key characteristics that enhance their experimental utility. Therefore, the present study is a foundation for cartilaginous fish research. Developmental Dynamics 247:712-723, 2018. © 2017 Wiley Periodicals, Inc.

© 2018 The Authors Developmental Dynamics published by Wiley Periodicals, Inc. on behalf of American Association of Anatomists.

KEYWORDS: Shark embryonic development; brownbanded bamboo shark; elasmobranchs; evolutionary developmental biology; ex ovo culture; fin development; staging table PMID: 29396887 PMCID: PMC5947634 DOI: 10.1002/dvdy.24623