Shedding new light on the evolution of the squid – Phys.Org

February 28, 2017 Belemnoteuthis antiquus NHM OR25966, a 166 million year old exceptionally preserved extinct squid-relative was found near Bristol (Christian Malford). These ancient cephalopods with their large internal shell were not as fast as their recently evolved relatives, which survived until today's squid and cuttlefish. Credit: Jonathan Jackson and Zo Hughes, NHMUK

Octopus, cuttlefish and squid are well known in the invertebrate world. With their ink-squirting decoy technique, ability to change colour, bizarre body plan and remarkable intelligence they highlight that lacking a back-bone doesn't always mean lacking sophistication.

Examining their deep evolutionary past, researchers have been spoiled by their generous fossil record, as demonstrated by drawer after drawer of ammonites and belemnites in every natural history museum shop. But, the mostly shell-less modern cephalopods have been less easy to understand.

Now a new study, led by researchers from the University of Bristol, has found out how these remarkable creatures evolved by comparing their fossil records with the evolutionary history chronicled in their gene sequences to shed light on their origins.

Published today in Proceedings of the Royal Society B, it shows that the cephalopods diversified into the familiar modern octopuses, cuttlefish and squid during a time of great change in the marine world, known as the Mesozoic Marine Revolution, 160 to 100 million years in the past.

Lead author, Al Tanner, a PhD student at the University of Bristol's School of Biological Sciences, is a molecular biologist and bioinformatician at the Bristol Palaeobiology Research Groupa world leading evolutionary research group.

He said: "On land this was the time of the dinosaurs, but beneath the seas, ecologies were changing rapidly. Fish, squid and their predators were locked in evolutionary 'arms-races', leading to increasingly speedy and agile predators and prey.

"The cephalopods are now known to have also been caught up in this major transition, evolving to lose the shells of their ancestors and develop as dynamic and uniquely adapted marine animals."

The researchers used a technique called molecular clocks to investigate the timing of when the groups split from each other. Bristol co-author, Professor Davide Pisani, added: "Complex Bayesian models take all sorts of information into account to build a tree of evolutionary time.

"The key element of molecular clocks though is the fact that mutations steadily accumulate in genetic material over time - so by figuring out how many mutations per million years you find, and how it may vary between different groups, we can estimate evolutionary time."

Al Tanner said: "The molecular clock results can be compared to the fossil record. What we see is that while there is some uncertainty in molecular clock estimates, octopuses and squid appear during the Mesozoic Marine Revolution and the two lines of evidence come together to tell the tale of evolution".

Co-author Dr Jakob Vinther said: "By having a reduced internal skeleton compared to their ancient relatives, the modern squids and octopuses could compress their body and more efficiently jet away leaving a baffling cloud of ink with the attacking predator. Before the predator realises what has happened and gains clear view again, the squid is far out of sight."

Al Tanner added: "The research exemplifies why evolutionary biologists are increasingly seeking to understand deep history from the combined study of both living organisms and the geological record. Through this synoptic view, so called molecular palaeontologists are transforming our understanding of how life became so complex and diverse."

Explore further: Despite multicolor camouflage, cuttlefish, squid and octopus are colorblind

More information: Molecular clocks indicate turnover and diversification of modern coleoid cephalopods during the Mesozoic Marine Revolution, Proceedings of the Royal Society B, rspb.royalsocietypublishing.org/lookup/doi/10.1098/rspb.2016.2818

Researchers at The University of Queensland have established that colourful coastal cephalopods are actually colourblind but can still manage to blend beautifully with their surroundings.

(Phys.org)An international team of researchers has found a trove of marine fossils at a North American site that offers evidence of life bouncing back faster than thought after the most devastating mass extinction in Earth's ...

A study by researchers at the University of Toronto and the Royal Ontario Museum sheds new light on a previously unclassifiable 500 million-year-old squid-like carnivore known as Nectocaris pteryx.

A team of researchers from the University of Bristol studying the 'living fossil' Sphenodon - or tuatara - have identified a new way to measure the evolutionary rate of these enigmatic creatures, giving credence to Darwin's ...

A previously undiscovered species of an extinct primordial giant worm with terrifying snapping jaws has been identified by an international team of scientists.

The researchers from the Bristol Palaeobiology Group, part of the School of Earth Sciences, studied the best way to understand relationships of extinct animals to other extinct species as well as those alive today.

Intensive selective breeding over the past 200 years and high extinction rates among feral populations has greatly reduced the genetic diversity present in domestic goat breeds. The effect these pressures have had on Irish ...

Octopus, cuttlefish and squid are well known in the invertebrate world. With their ink-squirting decoy technique, ability to change colour, bizarre body plan and remarkable intelligence they highlight that lacking a back-bone ...

A University of Florida study shows that mollusk fossils provide a reliable measure of human-driven changes in marine ecosystems and shifts in ocean biodiversity across time and space.

Organic additives found in road salt alternativessuch as those used in the commercial products GeoMelt and Magic Saltact as a fertilizer to aquatic ecosystems, promoting the growth of algae and organisms that eat algae, ...

The Zika virus taking hold of the inner organelles of human liver and neural stem cells has been captured via light and electron microscopy. In Cell Reports on February 28, researchers in Germany show how the African and ...

In the world of fungi, Aspergillus is an industrial superstar. Aspergillus niger, for example, has been used for decades to produce citric acida compound frequently added to foods and pharmaceuticals through fermentation ...

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Originally posted here:

Shedding new light on the evolution of the squid - Phys.Org