Brooding in the deep-sea sea anemone Actinostola crassicornis (Hertwig, 1882) (Cnidaria: Anthozoa: Actiniaria) from the
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ORIGINAL PAPER
Brooding in the deep‑sea sea anemone Actinostola crassicornis (Hertwig, 1882) (Cnidaria: Anthozoa: Actiniaria) from the southwestern Atlantic Ocean Daniel Lauretta1 · Camila Vidos1 · Mariano I. Martinez1 · Pablo E. Penchaszadeh1 Received: 3 May 2019 / Revised: 29 May 2020 / Accepted: 25 June 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Marine invertebrates can display several reproductive strategies, from external reproduction to parental care. Internal brooding is particularly relevant in harsh conditions, like Antarctic/sub-Antarctic waters and deep-sea, since it maximizes the survival of the young. Actinostola crassicornis is an abundant and widely distributed sea anemone from the southwestern Atlantic Ocean. It can be found all along the Argentinean sea down to 1200 m depth, usually in large numbers. It is a unique species in the area, since it is a large white brooding sea anemone. We studied 75 specimens collected by the O/V Walther Herwig and the O/V Puerto Deseado all along its distribution, from about 60 m to 800 m depth, in different seasons of the year. All the specimens were sexed, and the presence of free oocytes and juveniles inside the coelenteron were assessed. Large oocytes (over 500 μm) and juveniles were found in samples from most of the sampled months. We found a larger number of female specimens, and most of the brooding specimens were female. No early developmental stages were found smaller than a sea anemone with about 12 tentacles. We conclude that A. crassicornis reproduces continuously throughout the year and that although most of the juveniles were found in females, male specimens can breed. Brooding has great benefits in terms of protecting the offspring, since predation upon the juveniles is prevented, but dispersal of the offspring is low, shown by the aggregated distribution of the species. Keywords Actinostolidae · Argentina · Reproduction · Sub-Antarctic waters
Introduction Marine invertebrates can display several reproductive strategies, from external reproduction to parental care. Pelagic development of the larvae has been assumed to be plesiomorphic, so the particular reproductive strategy may be an adaptation to the particular environmental conditions or the reflection of a phyletic constraint (Pearse et al. 2009 and references herein). For example, despite the fact that parental care is quite common in the Southern Ocean, it seems not Lauretta Daniel and Vidos Camila have contributed equally to this work. * Camila Vidos [email protected] 1
Laboratorio de Ecosistemas Costeros, Plataforma y Aguas Profundas ‑ Malacología, Museo Argentino de Ciencias Naturales “Bernardino Rivadavia” (CONICET), Av. Ángel Gallardo 470 (C1405DJR), Buenos Aires, Argentina
to be related with the conditions of the area (Pearse et al. 2009). Sea anemones (Cnidaria: Actiniaria) are usually well represented in the benthic community. They are widely spread: from the intertidal zone to the oceanic depths and from the equator to the poles, but since
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