Posted on 09/22/2018 9:37:26 AM PDT by ETL
Did the octopus evolve its unique intelligence by playing fast and free with the genetic code? Elizabeth Finkel investigates
-BIG snip-
Some 400 million years ago, cephalopods – creatures named for the fact that their heads are joined to their feet – ruled the oceans. They feasted on shrimp and starfish, grew to enormous sizes like the six-metre long Nautiloid, Cameroceras, and used their spiral-shaped shells for protection and flotation.
Then the age of fishes dawned, dethroning cephalopods as the top predators. Most of the spiral-shelled species became extinct; modern nautilus was one of the few exceptions.
But one group shed or internalised their shells. Thus unencumbered, they were free to explore new ways to compete with the smarter, fleeter fish. They gave rise to the octopus, squid and cuttlefish – a group known as the coleoids.
Their innovations were dazzling. They split their molluscan foot, creating eight highly dexterous arms, each with hundreds of suckers as agile as opposable thumbs. To illustrate this dexterity, Mather relates the story of a colleague who found his octopus pulling out its stitches after surgery.
But those limber bodies were a tasty treat to fish predators, so the octopus evolved ‘thinking skin’ that could melt into the background in a fifth of a second. These quick-change artists not only use a palette of skin pigments to paint with, they also have a repertoire of smooth to spiky skin textures, as well as body and arm contortions to complete their performance – perhaps an imitation of a patch of algae, as they stealthily perambulate on two of their eight arms.
“It’s not orchestrated by simple reflexes,” says Roger Hanlon, who researches camouflage behaviour at the Marine Biological Laboratory in Woods Hole, Massachusetts. “It’s a context-specific, fast computation of decisions carried out in multiple levels of the brain.” And it depends critically on a pair of camera eyes with keen capabilities.
It takes serious computing power to control eight arms, hundreds of suckers, ‘thinking skin’ and camera eyes. Hence the oversized brain of the octopus. With its 500 million neurons, that’s two and a half times that of a rat. But their brain anatomy is very different.
A mammalian brain is a centralised processor that sends and receives signals via the spinal cord. But for the octopus, only 10% of its brain is centralised in a highly folded, 30-lobed donut-shaped structure arranged around its oesophagus (really). Two optic lobes account for another 30%, and 60% lies in the arms. “It’s a weird way to construct a complex brain,” says Hanlon. “Everything about this animal is goofy and weird.”
Take the arms: they’re considered to have their own ‘mini-brain’ not just because they are so packed with neurons but because they also have independent processing power. For instance, an octopus escaping a predator can detach an arm that will happily continue crawling around for up to 10 minutes.
Indeed, until an experiment by Kuba and colleagues in 2011, some suspected the arms’ movements were independent of their central brain. They aren’t. Rather it appears that the brain gives a high-level command that a staff of eight arms execute autonomously.
“The arm has some fascinating reflexes, but it doesn’t learn,” says Kuba, who studied these reflexes between 2009 and 2013 as part of a European Union project to design bio-inspired robots.
And then there’s their ‘thinking’ skin. Again the brain, primarily the optic lobes, controls the processing power here. The evidence comes from a 1988 study by Hanlon and John Messenger from the University of Sheffield. They showed that blinded newly hatched cuttlefish could no longer match their surroundings.
They were still able to change colour and body patterns but in a seemingly random fashion. Anatomical evidence also shows that nerves in the lower brain connect directly to muscles surrounding the pigment sacs or chromatophores.
Like an artist spreading pigment on a pallet, activating the muscles pulls the sacs apart spreading the chromatophore pigments into thin discs of colour. But the octopus is not composing a picture. Hanlon’s experiments with cuttlefish show they are deploying one of three pre-existing patterns – uniform, mottled or disruptive – to achieve camouflage on diverse backgrounds.
As far as detailed brain circuitry goes, researchers have made little progress since the 1970s when legendary British neuroscientist J.Z Young worked out the gross anatomy of the distributed coleoid brain. Escaping Britain’s dismal winter for the Stazione Zoologica in balmy Naples, Young’s research was part of an American Air Force funded project to search for the theoretical memory circuit, the ‘engram’.
“They were ahead of their time,” says Hanlon, who experienced a stint with Young in Naples. Nevertheless they were limited by the paucity of brain-recording techniques that were suited to the octopus.
It’s a problem that has continued to hold back the understanding of how their brain circuits work. “Is it the same as the way mammals process information? We don’t know,” says Ragsdale.
-BIG snip-
Fossils must really freak you out.
Fossils don’t freak me out at all. Millions of them were made during the great flood, you know, the one that God used to cover the earth during the life of Noah. You really should read and study both the Bible and how it holds up under both scientific and historical scrutiny. Hint: it holds up very, very well.
My fossil remnants of ammonites that lived and died 125 million years ago refute your timeline.
Did the dinosaurs and man coexist in your world? Are many of the creatures known only as fossils now extinct because Noah didn’t round them up and put them on the ark?
How did you determine your timeline for your fossils? Proof?
To your first question, yes. To your second question, I don’t know. I recommend you look up Pastor Paul Veit in Maine. He will be able to help you with additional questions. He can bring you more specific knowledge than I have. He is known as the Dinosaur Pastor.
Geology. From the Greek. Geo- for Earth, and logos, for principle or reason. The latter also has implications in theology. Empirical evidence can be one way that God speaks to us through nature.
I may look it up. Man and dinosaurs coexisted on The Fintstones and in some bad movies and TV. Until “Jurassic Park” comes to pass, that’s all.
Pastor Paul Veit travels and speaks all around the USA, even though he is Maine based. He is very down to earth and full of facts that you would appreciate. Thanks for the conversation. God bless you and your family.
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.