It’s possible that I shall make an ass of myself. But in that case one can always get out of it with a little dialectic. I have, of course, so worded my proposition as to be right either way (K.Marx, Letter to F.Engels on the Indian Mutiny)
Sunday, November 13, 2022
Octopuses caught on video throwing silt and shells around themselves and at each other
Octopus debris-throwing recorded for first time, at times during aggressive interactions with other octopuses
IMAGE: PANEL A — OCTOPUS (LEFT) PROJECTS SILT AND KELP THROUGH THE WATER; B – AN OCTOPUS (RIGHT) IS HIT BY A CLOUD OF SILT PROJECTED THROUGH THE WATER BY A THROWING OCTOPUS; C – SHELLS, SILT, ALGAE OR SOME MIXTURE IS HELD IN THE ARMS PREPARATORY TO THE THROW, MANTLE IS INFLATED PREPARATORY TO VENTILATION DURING THE THROW, SIPHON AT THIS STAGE MAY STILL BE VISIBLE IN ITS USUAL POSITION PROJECTING FROM THE GILL SLIT ABOVE THE ARM CROWN; D – SIPHON IS BROUGHT DOWN OVER REAR ARM AND UNDER THE WEB AND ARM CROWN BETWEEN THE REAR ARM PAIR (ARMS R4 AND L4), AND WATER IS FORCIBLY EXPELLED THROUGH THE SIPHON, WITH CONTRACTION OF THE MANTLE, AS HELD DEBRIS IS RELEASED, PROJECTING DEBRIS THROUGH THE WATER COLUMN. ILLUSTRATIONS BY REBECCA GELERNTER.view more
CREDIT: GODFREY-SMITH ET AL., 2022, PLOS ONE, CC-BY 4.0 (HTTPS://CREATIVECOMMONS.ORG/LICENSES/BY/4.0/)
Octopuses appear to deliberately throw debris, sometimes directed at other octopuses, according to a study publishing November 9 in the open-access journal PLOS ONE led by Peter Godfrey-Smith at the University of Sydney and colleagues.
Researchers recorded the behavior of gloomy octopuses (Octopus tetricus) in Jervis Bay, Australia in 2015 and 2016 using underwater video cameras. They analyzed 24 hours of footage across several days and identified 102 instances of debris throwing in a group of roughly 10 octopuses, although individual identification was not always possible.
Octopuses gathered material such as silt or shells, and released it while using a jet of water from their siphon (a tube-shaped structure that can eject water at speed) to propel it between their arms and through the water, often throwing material several body lengths away. To perform the throws, octopuses had to move their siphon into an unusual position, suggesting the behavior was deliberate. Both sexes were observed throwing, but 66% of throws were performed by females. Around half of throws occurred during or around the time of interactions with other octopuses, such as arm probes or mating attempts, and about 17% of throws hit other octopuses. Octopuses can change their skin coloration, with dark colors generally associated with aggression, and the researchers found that dark-colored individuals tended to throw more forcefully and were more likely to hit another octopus. Octopuses hit by thrown material often altered their behavior by ducking or raising their arms in the direction of the thrower.
This is the first time that throwing behavior has been reported in octopuses. The authors say that although it is difficult to determine the intent of octopuses propelling debris through the water, the behaviors observed suggest that at least in some social contexts, octopuses are capable of targeted throws towards other individuals, a behavior that has only been observed previously in a few non-human animals.
The authors add: “Wild octopuses project various kinds of material through the water in jet-propelled ‘throws,’ and these throws sometimes hit other octopuses. There is some evidence that some of these throws that hit others are targeted, and play a social role.”
Citation: Godfrey-Smith P, Scheel D, Chancellor S, Linquist S, Lawrence M (2022) In the line of fire: Debris throwing by wild octopuses. PLoS ONE 17(11): e0276482. https://doi.org/10.1371/journal.pone.0276482
Author Countries: Australia, USA, Canada
Funding: General financial support was provided to PGS by the City University of New York (https://www.cuny.edu) and to DS through Alaska Pacific University (https://www.alaskapacific.edu) from donations by the Pollock Conservation Consortium. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
IMAGE: FOUR SQUID EMBRYOS IN THEIR EGG SAC. THESE ARE THE SQUID SPECIES DORYTEUTHIS PEALEII.view more
CREDIT: KRISTEN KOENIG
Cephalopods — which includes octopus, squid, and their cuttlefish cousins — are capable of some truly charismatic behaviors. They can quickly process information to transform shape, color, and even texture, blending in with their surroundings. They can also communicate, show signs of spatial learning, and use tools to solve problems. They’re so smart, they can even get bored.
It’s no secret what makes it possible: Cephalopods have the most complex brains of any invertebrates on the planet. What remains mysterious, however, is the process. Basically, scientists have long wondered how cephalopods get their big brains in the first place? A Harvard lab that studies the visual system of these soft-bodied creatures — which is where two-thirds of their central processing tissue are focused — believe they’ve come close to figuring it out. The process, they say, looks surprisingly familiar.
Researchers from the FAS Center for Systems Biology describe how they used a new live-imaging technique to watch neurons being created in the embryo in almost real-time. They were then able to track those cells through the development of the nervous system in the retina. What they saw surprised them.
The neural stem cells they tracked behaved eerily similar to the way these cells behave in vertebrates during the development of their nervous system. It suggests that vertebrates and cephalopods, despite diverging from each other 500 million years ago, not only are using similar mechanisms to make their big brains but that this process and the way the cells act, divide, and are shaped may essentially layout the blueprint required develop this kind of nervous system.
“Our conclusions were surprising because a lot of what we know about nervous system development in vertebrates has long been thought to be special to that lineage,” said Kristen Koenig, a John Harvard Distinguished Fellow and senior author of the study. “By observing the fact that the process is very similar, what it suggested to us is that these two independently evolved very large nervous systems are using the same mechanisms to build them. What that suggests is that those mechanisms — those tools — the animals use during development may be important for building big nervous systems.”
The scientists from the Koenig Lab focused on the retina of a squid called Doryteuthis pealeii, more simply known as a type of longfin squid. The squid grow to be about a foot long and are abundant in the northwest Atlantic Ocean. As embryos the look quite adorable with big head and big eyes.
The researchers used similar techniques to those made popular to study model organisms, like fruit flies and zebrafish. They created special tools and used cutting edge microscopes that could take high resolution images every ten minutes for hours on end to see how individual cells behave. The researchers used florescent dyes to mark the cells so they could map them and track them.
This live-imaging technique allowed the team to observe stem cells called neural progenitor cells and how they are organized. The cells form a special kind of structure called a pseudostratified epithelium. Its main feature is the cells are elongated so they can be densely packed. The researchers also saw the nucleus of these structures move up and down before and after dividing. This movement is important for keeping the tissue organized and growth continuing, they said.
This type of structure is universal in how vertebrate species develop their brain and eyes. Historically, it was considered one of the reasons the vertebrate nervous system could grow so large and complex. Scientists have observed examples of this type of neural epithelium in other animals, but the squid tissue they looked at in this instance was unusually similar to vertebrate tissues in its size, organization and the way the nucleus moved.
The research was led by Francesca R. Napoli and Christina M. Daly, research assistants in the Koenig Lab.
Next, the lab plans to look at how different cell types in cephalopod brains emerge. Koenig wants to determine whether they’re expressed at different times, how they decide to become one type of neuron versus another, and whether this action is similar across species.
Koenig is excited about the potential discoveries that lie ahead.
“One of the big takeaways from this type of work is just how valuable it is to study the diversity of life,” Koenig said. “By studying this diversity, you can actually really come back to fundamental ideas about even our own development and our own biomedically relevant questions. You can really speak to those questions.”
No comments:
Post a Comment