title: Comparative embryology of eleven species of stony corals (Scleractinia).
abstract: A comprehensive understanding of coral reproduction and development is needed because corals are threatened in many ways by human activity. Major threats include the loss of their photosynthetic symbionts (Symbiodinium) caused by rising temperatures (bleaching), reduced ability to calcify caused by ocean acidification, increased storm severity associated with global climate change and an increase in predators caused by runoff from human agricultural activity. In spite of these threats, detailed descriptions of embryonic development are not available for many coral species. The current consensus is that there are two major groups of stony corals, the "complex" and the "robust". In this paper we describe the embryonic development of four "complex" species, Pseudosiderastrea tayamai, Galaxea fascicularis, Montipora hispida, and Pavona Decussata, and seven "robust" species, Oulastrea crispata, Platygyra contorta, Favites abdita, Echinophyllia aspera, Goniastrea favulus, Dipsastraea speciosa (previously Favia speciosa), and Phymastrea valenciennesi (previously Montastrea valenciennesi). Data from both histologically sectioned embryos and whole mounts are presented. One apparent difference between these two major groups is that before gastrulation the cells of the complex corals thus far described (mainly Acropora species) spread and flatten to produce the so-called prawn chip, which lacks a blastocoel. Our present broad survey of robust and complex corals reveals that prawn chip formation is not a synapomorphy of complex corals, as Pavona Decussata does not form a prawn chip and has a well-developed blastocoel. Although prawn chip formation cannot be used to separate the two clades, none of the robust corals which we surveyed has such a stage. Many robust coral embryos pass through two periods of invagination, separated by a return to a spherical shape. However, only the second of these periods is associated with endoderm formation. We have therefore termed the first invagination a pseudo-blastopore.
authors.affiliation: Research and Education Center for Natural Sciences, Keio University, Yokohama, Kanagawa, Japan ; Seto Marine Biological Laboratory, Field Science Education and Research Center, Kyoto University, Nishimuro, Wakayama, Japan ; Evolution, Ecology and Genetics Group, Research School of Biology, Australian National University, Canberra, Australian Capital Territory, Australia.
authors.forename: Nami
authors.initials: N
authors.lastname: Okubo
authors.affiliation: Kuroshio Biological Research Foundation, Hata, Kochi, Japan.
authors.forename: Takuma
authors.initials: T
authors.lastname: Mezaki
authors.affiliation: Biodiversity Research Center, Academia Sinica, Taipei, Taiwan, Republic of China.
authors.forename: Yoko
authors.initials: Y
authors.lastname: Nozawa
authors.affiliation: Tropical Biosphere Research Center, Sesoko Station, Ryukyu University, Motobu, Okinawa, Japan.
authors.forename: Yoshikatsu
authors.initials: Y
authors.lastname: Nakano
authors.affiliation: Seto Marine Biological Laboratory, Field Science Education and Research Center, Kyoto University, Nishimuro, Wakayama, Japan.
authors.forename: Yi-Ting
authors.initials: YT
authors.lastname: Lien
authors.affiliation: Faculty of Agriculture, Miyazaki University, Gakuen-Kibanadai-Nishi, Miyazaki, Japan.
authors.forename: Hironobu
authors.initials: H
authors.lastname: Fukami
authors.affiliation: Evolution, Ecology and Genetics Group, Research School of Biology, Australian National University, Canberra, Australian Capital Territory, Australia.
authors.forename: David C
authors.initials: DC
authors.lastname: Hayward
authors.affiliation: Evolution, Ecology and Genetics Group, Research School of Biology, Australian National University, Canberra, Australian Capital Territory, Australia.
authors.forename: Eldon E
authors.initials: EE
authors.lastname: Ball
mesh_terms: D000818:Animals; D037421:Anthozoa / Q000196:embryology*; D005855:Germ Layers / Q000196:embryology; D013045:Species Specificity