How long have cephalopods been around

If it collects mutations as a result of DNA mutations, it would no longer be recognized by the editing enzymes. We normally think of mutations as the currency of evolution. But in this case their accumulation is suppressed.

In University of Chicago neurobiologist Clifton Ragsdale and his team published the first cephalopod genome, that of an octopus. Clifton also noticed an unusually high degree of RNA editing.

No one knows why cephalopods are so keen on RNA editing. Perhaps it is a faster, easier way to adapt to their environment than waiting for a random mutation to occur. Or maybe it better suits their relatively short life spans. Cephalopods grow up fast and die young. Most live only for a few years and they only breed once. Ragsdale feels RNA editing may help them navigate what are often lonesome, fleeting lives.

How to camouflage themselves and attack prey. We want to see which environmental variables influence the RNA editing process—things like variation in temperature…maybe something more complex like experiences. But others maintain that the unique structure was purely a defensive mechanism that allowed the small creature to retreat into its shell in a way that left it inaccessible to predators. These feats of deduction and induction are a reminder that the true protagonists of Squid Empire are not the cephalopods, but the scientists who work on them.

Ultimately, Staaf is telling their story, not that of their tentacled-subjects. A book like Squid Empire is a reminder that in any scientific narrative, there are always two stories at play.

A constant difficulty of any science writer is to give both stories their due, particularly since each has its own chronology and pace. Too often, however, we end up prioritizing the latter, telling a story of human ingenuity and technology, while the world itself—filled with its wonders and strangeness—is reduced to merely the backdrop.

Cephalopods present perhaps a more striking version of this dilemma than other animals, because they are so obviously intelligent, and so completely unlike us. There are other animals whose intelligence likely rivals our own: elephants, dolphins, primates, whales, dogs.

But these are all vertebrate mammals, and their reasoning, to different degrees, often mirrors our own. Cephalopods are wonderfully alien, and how their intelligence works is even more of a mystery. Their brains are tripartite: They have an optic lobe behind each eye, each connected to a central ring of nervous tissue through which their esophagus runs.

Together with Dr Gregor Austermann, she headed the research projects carried out in cooperation with the Bavarian Natural History Collections. The chalky shells of the fossils found on the eastern Avalon Peninsula are shaped like a longish cone and subdivided into individual chambers. These are connected by a tube called the siphuncle. The cephalopods were thus the first organisms able to move actively up and down in the water and thus settle in the open ocean as their habitat.

The fossils are distant relatives of the spiral-shaped nautilus, but clearly differ in shape from early finds and the still existing representatives of that class. But there was a lack of fossil evidence to back up this theory.

The former and little explored micro-continent of Avalonia, which -- besides the east coast of Newfoundland -- comprises parts of Europe, is particularly suited to paleontological research, since many different creatures from the Cambrian period are still preserved in its rocks.

The researchers hope that other, better preserved finds will confirm the classification of their discoveries as early cephalopods. Unlike the squid and octopus, the nautilus sports dozens of sucker-less tentacles, a leathery hood, a pinhole eye, and lacks an ink sac.

Given the long history of their lineage, these features were once thought to reflect what early cephalopods looked like in life. But studies of nautilus embryos suggest otherwise. Though our tailbone is no more than a stub, we humans start out in the womb with a visible tail, a reminder of our ancestry. Nautilus embryos too, reveal that their ancestor likely had ten arms before splitting into dozens of tentacles somewhere in the evolutionary line.

The earliest forms of cephalopods would look unfamiliar to today's viewers. Top left: Plectronoceras , top right: Phragmoceras , bottom: Sphooceras.

Unlikely as it may be, there have been some ancestral cephalopod shell fossils discovered largely intact, even with traces of coloration and growth stages. Take Sphooceras , for example. Shelled cephalopods are born small, then they keep adding new material to renovate a bigger house while keeping their baby crib intact.

Multiple Sphooceras fossils found to represent different stages of its life suggest that in adulthood, Sphooceras actually lost its baby coils. Another fascinating early cephalopod to talk about is Phragmoceras , which is about the same age as Sphooceras.

There are multiple forms known to science, some had striped patterns while others had zigzags near the opening side of the shell. It suggests that they were probably a group of adaptable animals that disguised themselves with different patterns depending on which part of the water they lived in. Unfortunately, not much is known about the earliest cephalopod. There are multiple fossil specimens named Plectronoceras , estimated to be million years old, but none of them are complete.

Despite this, its shape matches the estimated ancestor of all cephalopods, with an air-filled chambered shell that looks like a gnome hat. This kind of modification helped cephalopods stay buoyant and not tied to the ocean floor. Such a new lifestyle set them apart from their close relatives, the snails. Our search for the ancient cephalopods is far from over. Somewhere out there, there are more fossils waiting to be discovered, each one having their own story to tell.

But even with our limited knowledge, we can already see that our squishy cohabitants are the protagonists in their own narrative. Danna Staaf's book Squid Empire: The Rise and Fall of the Cephalopods and her insight have brought forth the latest developments in cephalopod paleontology that are otherwise difficult to track down. References: Danna Staaf. Proteroctopus ribeti in coleoid evolution.

Joanne Kluessendorf, Peter Doyle. Palaeontology 43 5 :