Previous observations suggest the existence of 'Active sleep' in cephalopods. To investigate in detail the behavioral structure of cephalopod sleep, we video-recorded four adult specimens of Octopus insularis and quantified their distinct states and transitions. Changes in skin color and texture and movements of eyes and mantle were assessed using automated image processing tools, and arousal threshold was measured using sensory stimulation. Two distinct states unresponsive to stimulation occurred in tandem. The first was a 'Quiet sleep' state with uniformly pale skin, closed pupils, and long episode durations (median 415.2 s). The second was an 'Active sleep' state with dynamic skin patterns of color and texture, rapid eye movements, and short episode durations (median 40.8 s). 'Active sleep' was periodic (60% of recurrences between 26 and 39 min) and occurred mostly after 'Quiet sleep' (82% of transitions). These results suggest that cephalopods have an ultradian sleep cycle analogous to that of amniotes.

Many marine species once considered to be cosmopolitan are now recognised as cryptic species complexes. Mitochondrial markers are ubiquitously used to address phylogeographic questions, and have been used to identify some cryptic species complexes; however, their efficacy in inference of evolutionary processes in the nuclear genome has not been thoroughly investigated. We used double digest restriction siteassociated DNA sequencing (ddRADseq) markers to quantify species boundaries in the widely distributed and high value common octopus, Octopus vulgaris, comparing genome-wide phylogenetic signal to that obtained from mitochondrial markers.Phylogenetic analyses, genome-wide concordance and species tree estimation based on 604 genome-wide ddRADseq loci revealed six species within the O. vulgaris group.Divergence time estimates suggested modern-day species evolved over the last 2.5 ma, during a period of global cooling. Importantly, our study identified significant phylogenetic discordance between mitochondrial and nuclear markers; genome-wide nuclear loci supported O. vulgaris sensu stricto and Type III (South Africa) as distinct species, which mtDNA failed to recognise. Our finding of conflicting phylogenetic signal between mitochondrial and nuclear markers has broad implications for many taxa.Improved phylogenetic resolution of O. vulgaris has significant implications for appropriate management of the group and will allow greater accuracy in global fisheries catch statistics.

In the Atlantic Ocean, Octopus insularis (Cephalopoda: Octopodidae) Leite and Haimovici, 2008 inhabits warm and shallow habitats, where it is one of the main targets of cephalopod fisheries. Considering the current trend of increasing seawater temperature, warm-water species are expected to expand their geographic distribution ranges. Ecological niche modeling (ENM) is an important tool to help describe likely changes in geographic distribution patterns of a species in different climatic scenarios. To evaluate changes in the distribution of Octopus insularis over time, the maximum entropy approach was used, which estimated a suitable climatic niche for Octopus under 5 scenarios of global climate change. Four environmental variables were chosen to model the suitable climatic niche of O. insularis in the present, past, and future scenarios. The ENM in different climatic scenarios showed good validation and pointed out an increase of the suitable niche for O. insularis settlement, from the Last Glacial Maximum (21 kya) up to future scenarios. In the future projections, suitable niche space will potentially increase in the tropical Atlantic compared to the current distribution. Modeling pointed out the possibility of expansion from the current range of the species to the temperate northern Atlantic, temperate South America, and temperate South Africa. This may cause potential threats, such as possible extinction of endemic species, habitat displacement of native octopuses, and reorganizations in the trophic chain.

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