New Analysis Shows Chephalopod Genomes Are Even Weirder Than You'd Expect

Squishy cephalopods have many clever features, including brained arms, escape artistry, and puzzle-solving skills. The genetics of squid, octopus, and cuttlefish are just as weird as the animals themselves.

The cephalopod genome is churned up, according to developmental Biologist, Caroline Albertin, who led one of two new studies.

The California two-spot octopus is the first of the soft-bodied cephalopods to have its genome mapped back in 2005.

The bobtail squid uses its color gene clusters. The images are from David_Slater/iStock.

The researchers found a bunch of new gene families, many expressed in the squid brain, as well as expansions in genes we are already familiar with, like clusters of genes involved with shifting coloration, their suckers, and beaks.

The genes that may be involved in building complex nervous systems in humans and cephalopods are included in other unique genes. In humans, this variation comes about in the different ways the genes are expressed.

The California two-spot octopus is 90 percent the size of ours, and the Doryteuthis is 1.5 times larger, thanks to these copies.

Our genomes expanded through the process of whole genome duplication, a feature credited for our advanced complexity and its ability to create new evolutionary features. As with many things they do, ceps have added their own unique flavor.

We now know that the evolution of soft-bodied cephalopods involved similar massive genome changes, but the changes are not whole-genome duplications but rather immense genome rearrangements, as if the ancestral genomes were put in a blender.

The squid is from the Atlantic. Elaine Bearer.

These unique sea beasties may have been helped by this genetic shuffling by being able to use their large nervous systems. Between their arms and their heads, the amount of neurons possessed by dogs is roughly 500 million.

We compared the squid genome to that of a scallop, and we found that many genes that were scattered in the scallop genome had come together on specific areas of the squid chromosomes. Regulatory units are formed by the new gene clusters. The second study that took a closer look at the bobtail squid's genome shows that they can interact with each other.

One of the genes in the squid genome is involved in the development of the nervous system.

The clustering of genes allowed for different forms of genetic regulation.

There is a California two-spot octopus. (Tom Kleindinst)

The cephalopod has a famous ability to modify their own brain genes. In humans, less than 1 percent of nervous system proteins have this ability, but in cephalopods, it is much more widespread.

Changes to an animal's construction are usually due to genetic changes. The messenger RNA is making the changes. There is a suggestion that this ability allows the builder to adapt to new conditions, but this is still not fully established.

Albertin and her team found that the animals have two different types of edits, neural and non-neural. Not only do these occur in different tissues, but the frequency in which they occur is vastly different, suggesting that it is very important to how these animals function.

In the 300 million years since squid and octopus last shared a common ancestor, these unusual mechanisms have contributed to building alien intelligences. We can't wait to find out what else their strange genomes reveal.

The research was published in Nature Communications.