Extended Pelagic Life in a Bathybenthic Octopus

Planktonic stages of benthic octopuses can reach relatively large sizes in some species, usually in oceanic, epipelagic waters while living as part of the macroplankton. These young octopuses appear to delay settlement on the seabed for an undetermined period of time that is probably longer than for those octopus paralarvae living in coastal, neritic waters. The reason for this delay is unknown and existing information about their biology is very scarce. Here we report on the presence of juvenile and subadult forms of the bathybenthic octopus Pteroctopus tetracirrhus in oceanic waters of the South and North Atlantic and its association with the pyrosomid species Pyrosoma atlanticum, apparently used by the octopus as a refuge or shelter. The relatively large size of the P. tetracirrhus living in oceanic waters as the individuals reported here, together with the morphological characteristics of this bathybenthic species including its gelatinous body, minute suckers embedded in swollen skin and the deep interbrachial web, indicates that P. tetracirrhus may be considered a model of a transitional octopus species that is colonizing the pelagic environment by avoiding descending to the bathyal benthos. This process seems to occur in the same way as in the supposed origin of the ctenoglossan holopelagic octopods of the families Amphitretidae, Bolitaenidae, and Vitreledonellidae, which have arisen via neoteny from the planktonic paralarval stages of benthic octopuses.© 2020 Villanueva, Laptikhovsky, Piertney, Fernández-Álvarez, Collins, Ablett and Escánez. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms

First record of an adult Taningia danae (Cefalopoda: Octopoteuthidae) in the Canary Islands (Central-east Atlantic)

The deep-sea hooked squid, Taningia danae Joubin, 1931 (Octopoteuthidae) is one of the largest oceanic squids, reaching dorsal mantle lengths (DML) of 1700 mm (Nesis 1982; 1987), and has been reported to weigh up to at least 161.4 kg (Roper & Vecchione 1993). This species is characterised by a conical mantle with large triangular fins that occupy almost the entire mantle length and its width exceeds up to 130% of the DML. This species has eight short robust arms, with two series of hooks on each arm, and arm pair II with two large oval terminal photophores, which are covered by black eyelidlike skin folds that allow for the controlled flashing of each photophore. Another pair of photophores is embedded on each side of the ink sac. Tentacles are robust on paralarvae but are lost at a dorsal mantle length of 40 to 45 mm (Jereb & Roper 2010). This species has a cosmopolitan distribution, being more abundant in tropical and temperate waters, but has also been observed in boreal areas, e.g. 57º N in the NE Atlantic. Paralarval and juvenile individuals of T. danae have been caught within Scottish waters (Santos et al. 2001), the North Atlantic Ocean (Clarke & Lu 1974; Okutani 1974; Lu & Clarke 1975), and off Bermuda, Cape Verde and the Madeira Islands (Roper & Vecchione 1993). In the Pacific Ocean the species has been reported from the Hawaiian Islands and New Zealand (Roper & Vecchione 1993) and in the Mediterranean Sea from Algerian waters (Quetglas et al. 2006). Santos et al. (2001) reported an incomplete adult female caught at 400 m depth by a commercial trawler in Galician waters. Posteriorly, González et al. (2003) recorded three specimens (two females and a mature male), in the Carrandi fishing ground (Cantabrian sea). A further large specimen (1600 mm ML) was captured at Georges Bank (USA) in the NW Atlantic (Roper & Vecchione 1993). Three living specimens have been video-recorded: two in the Ogasawara Islands’ waters (Japan), in the western North Pacific at 240 and 900 m depth (Kubodera et al. 2007) and one in the waters of the Azores (Seine Seamount) at 2717 m depth (Gomes-Pereira & Tojeira 2014). Despite the small number of catches of large individuals of T. danae, several hundred large beaks have been recorded from sperm whale (Physeter macrocephalus) stomach contents, suggesting that it is not a rare deep-sea squid species in tropical and subtropical oceans (e.g. Clarke et al. 1993; Smith & Witehead 2000; Evans & Hindell 2004; Clarke 2006). In the Canary Islands, previous records of T. danae come from beaks found in the stomach contents of three Cuvier's beaked whales (Ziphius cavirostris) stranded in Lanzarote and Fuerteventura in 2002 (Santos et al. 2007) and from the stomach contents of a sperm whale stranded in Fuerteventura in 2005 (Fernández et al. 2009). Later, Bordes et al. (2009) reported three juvenile individuals of 30-100 mm ML caught in mesopelagic trawling nets around Gran Canaria and on the south-eastern side of Fuerteventura in 2000 and 2002. This study reports the occurrence of the first adult deep-sea hooked squid in the Canarian archipelago. The studied specimen was collected off SW Tenerife, confirming the presence of all life stages of this species in Canary waters.En prens

Opportunistic acoustic recordings of (potential) orangeback flying squid Sthenoteuthis pteropus in the Central Eastern Atlantic

7 pages, 6 figures, 1 tableSquids are fast swimmers that are difficult to catch by nets and to record with echosounders in the open ocean. A rare detection of orangeback flying squid Sthenoteuthis pteropus in the Central Eastern Atlantic Ocean off the coast of Senegal was accomplished during the MAFIA oceanographic survey carried out between Brazil and the Canary Islands in April 2015. Although net sampling did not yield any subadult or adult individuals, dozens were visually detected from the vessel jumping out of the water at night and displaying their characteristic dorsal photophore patch. A few squids were caught with fishing lines and identified at the species level. The acoustic echograms revealed distinctive previously unobserved acoustic echotraces that seemed to be caused by those squids, which were the only new species detected at that station (over a bottom depth ranging from 4010 to 5215 m, between 10° 45′ N 22° 41′ W and 10° 53′ N 22° 40′ W). The acoustic response and swimming behaviour shown by those echotraces reinforced this hypothesis. The (potentially) squid recordings dove rapidly (0.19 m/s to 0.48 m/s) from around 10 m below the mesopelagic fish layer, which had migrated to the subsurface at night (35 m depth), to depths of 70–95 m, and swam upward, apparently attacking fish from below. The morning squid migration to deeper waters (250–300 m) was also recorded acoustically. Downward movements of squid swimming at speeds of 0.22 m/s were calculated from the echogram, while the mesopelagic migrating fish swam at 0.27 m/s reaching 250 m depth. S − S averaged 2.7 ± 3.2 dB for the squid echotraces while the mesopelagic layer showed values of −8.8 ± 0.9 dB. These ranges agreed with values in the literature and from theoretical models. This study provides more insight into the migrating behaviour of oceanic squids, a species group that is poorly represented in the acoustic literature due to challenges in studying themThis research was funded by Spanish Ministerio de Economía y Competitividad (MINECO) through project CTM2012-39587-C04-03. RV was financed by the MINECO project AGL2012-39077Peer Reviewe