Welcome To Octlantis

Communal Living Among Cephalopods

Evolution, Natural Selection, Medicine, Psychology & Neuroscience.

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Welcome To Octlantis

#1  Postby Calilasseia » Sep 23, 2017 2:19 am

Welcome to Octlantis.

What is this place, I hear you ask?

It's a communal octopus settlement. Yes, that's right, it's a place where individuals of an octopus species known as the Gloomy Octopus, Octopus tetricus, live and interact communally, in a manner that has only recently been alighted upon by scientists, and which could, upon further study, rewrite some of the content of textbooks on cephalopod behaviour. As might be expected, a scientific paper documents the find, namely this one:

A Second Site Occupied By Octopus tetricus At High Densities, With Notes On Their Ecology And Behaviour by David Scheel, Stephanie Chancellor, Martin Hing, Matthew Lawrence, Stefan Linquist & Peter Godfrey-Smith, Marine And Freshwater Behaviour And Phsyiology, DOI: 10.1080/10236244.2017.1369851 (1st September 2017) [paper can be read in full online here]

Scheel et al, 2017 wrote:Abstract

We report wild octopuses (Octopus tetricus) living at high density at a rock outcrop, the second such site known. O. tetricus are often observed as solitary individuals, with the species known to exist at similar densities and exhibiting complex social behaviors at only one site other than that described here. The present site was occupied by 10–15 octopuses on eight different days. We recorded frequent interactions, signaling, mating, mate defense, eviction of octopuses from dens, and attempts to exclude individuals from the site. These observations demonstrate that high-density occupation and complex social behaviors are not unique to the earlier described site, which had been affected to some extent by remains of human activity. Behavior at this second site confirms that complex social interactions also occur in association with natural substrate, and suggest that social interactions are more wide spread among octopuses than previously recognized.

The authors open with this:

Scheel et al, 2017 wrote:Introduction

A growing number of studies show that some species of octopuses are not as habitually solitary and asocial as previously supposed. Recent studies have documented aspects of social behavior, such as aggregation, interaction, and signaling, in several octopus species (e.g. Abdopus aculeatus, Huffard 2007; Larger Pacific Striped Octopus, Caldwell et al. 2015; Octopus tetricus, Scheel et al. 2016). Much of this change in the perceptions of octopuses has happened over the past decade: Boal (2006) in a review of social recognition in cephalopods listed only three species (Octopus joubini, O. briareus, O. bimaculoides) reported to occur at high densities in the wild as exceptions to the description of octopuses as “generally solitary.” Ten years later, Scheel et al. (2016) included 14 species as exceptions to the “predominant view that octopuses are solitary and asocial.”

Among the species recently recognized as exceptions is the gloomy octopus, Octopus tetricus Gould, 1852. This species commonly can be observed as solitary individuals (Anderson 1997), but Godfrey-Smith and Lawrence (2012) described a single site at which O. tetricus occurs in high density, interacts, and mates – the only such site known to exist at the time. Their observations were from a field site in Jervis Bay on the east coast of Australia at a depth of 17 m. The site was discovered by Matthew Lawrence in 2009 and comprised an extended midden forming a bed of shell hash around what is probably a single human artifact, of unknown origin (Godfrey-Smith & Lawrence 2012 ; Scheel et al. 2014). The artifact is a single flat object about 30 cm long, heavily encrusted but possibly made of metal, that we have not identified. The site has been observed occupied by 2 to 16 octopuses since its discovery through December 2016 (Scheel et al. 2014, 2016).

Shelters have important roles in octopus ecology (e.g. Octopus bimaculatus, Ambrose 1982 ; O. tehuelchus, Iribarne 1990), and remarkably so at this site. Godfrey-Smith and Lawrence (2012) hypothesized that the artifact provided a locus for initial settlement. Octopuses carry prey items back to their dens for consumption and discard the hard remains in a midden pile, leading to the formation of the extended shell bed of discarded remains. As the shell bed expanded and stabilized surrounding soft sediment, additional octopuses were able to excavate dens. Scheel et al. (2014) have further argued that the expanding shell bed provides resources for other organisms, and thus that the octopuses were acting as ecosystem engineers. The key role of a human artifact in this scenario raises the question whether the behavioral interactions at this site could occur without the anthropogenic object providing hard shelter in a soft-sediment environment.

In this note, we report the discovery of a second site where O. tetricus is found at high densities, and interacts in similar ways to those described at the original site. The second site was discovered by Martin Hing and Kylie Brown in December 2016, at 10–15 m depth a few hundred meters distant from the first site. Hing reported the site to researchers working at the original site nearby. Subsequently, divers David Scheel and Stephanie Chancellor surveyed the second site and left cameras to record octopus behavior. We also include in this report observations made informally during recreational dives on several subsequent days. Video recorded at this site is still being analyzed, and more detailed analyses of the behavior will be forthcoming.

The previous site where this species was observed living communally, dubbed "Octopolis", was considered to be unusual, in part because the site was centred upon a large discarded human artefact, which the octopus species may have chosen opportunistically as a den site. The latest site, "Octlantis", however, involves no pre-discarded human remains embedded in the substrate, though beer bottles and caps materialising at the site after den construction have been relocated to midden piles by the octopus residents.

As a consequence of observations made at this site, which include such gems as "evictions" of occupants from dens, the existence of unoccupied dens (this is beginning to sound like the octopus version of London :mrgreen: ) and territorial behaviour involving attempts to exclude certain octopus individuals from entering the site, the repertoire of observed cephalopod social behaviour has now expanded.
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Re: Welcome To Octlantis

#2  Postby Rumraket » Sep 23, 2017 8:28 am

What happened, they didn't pay the rent on time? :grin:

Naturally the mind wonders about alternative evolutionary histories where Octopi/Octopussies(YEAH, I SAID IT) evolve complex societies, cooperation and ultimately technology.
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Re: Welcome To Octlantis

#3  Postby DavidMcC » Sep 23, 2017 9:46 am

Rumraket wrote:What happened, they didn't pay the rent on time? :grin:

Naturally the mind wonders about alternative evolutionary histories where Octopi/Octopussies(YEAH, I SAID IT) evolve complex societies, cooperation and ultimately technology.

They woud have to be brave (probably to the point of suicidal) to exploit under-water volcanoes as their heat source for technology!
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