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.

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深海章鱼的远洋寿命延长

底栖章鱼的浮游阶段在某些物种中可以达到相对较大的尺寸，通常在海洋、上层水域，同时作为大型浮游生物的一部分生活。这些年轻的章鱼似乎会在一段不确定的时间内延迟在海床上的定居，这可能比生活在沿海浅海水域的那些章鱼副幼虫要长。这种延迟的原因是未知的，关于它们生物学的现有信息非常稀少。在这里，我们报告了南大西洋和北大西洋海域中深海底栖章鱼 Pteroctopus tetracirrhus 的幼年和亚成体形式的存在，及其与 Pyrosoma atlanticum 的关联，显然被章鱼用作避难所或庇护所。生活在海洋水域的 P. tetracirrhus 的体型相对较大，正如这里的个体所报告的那样，连同这种深海底栖物种的形态特征，包括其凝胶状体、嵌入肿胀皮肤的微小吸盘和深臂间网，表明 P. tetracirrhus 可被视为过渡章鱼物种的模型，该物种通过避免下降而定殖于远洋环境到深海底栖生物。这个过程似乎与 Amphitretidae、Bolitaenidae 和 Vitreledonellidae 科的 ctenoglossan 全息八足类的假定起源相同，它们是通过底栖章鱼的浮游副幼体阶段的幼体产生的。tetracirrhus 可被视为过渡章鱼物种的模型，该物种通过避免下降到深海底栖动物而在远洋环境中定殖。这个过程似乎与 Amphitretidae、Bolitaenidae 和 Vitreledonellidae 科的 ctenoglossan 全息八足类的假定起源相同，它们是通过底栖章鱼的浮游副幼体阶段的幼体产生的。tetracirrhus 可被视为过渡章鱼物种的模型，该物种通过避免下降到深海底栖动物而在远洋环境中定殖。这个过程似乎与 Amphitretidae、Bolitaenidae 和 Vitreledonellidae 科的 ctenoglossan 全息八足类的假定起源相同，它们是通过底栖章鱼的浮游副幼体阶段的幼体产生的。