Squid: Your New Favorite Scientific Critter!

Aug 20, 2020

The Caribbean Reef squid uses chromatophores to change the colors and patterns on its body. hhttps://en.wikipedia.org/wiki/File:Squid_colors _2.jpg).

By Rami Major

Scientific researchers spend large portions of their days asking hard questions and searching for answers and it’s not uncommon for scientists to themselves conducting dozens or even hundreds of experiments to answer a single question!  Research experiments can include observing the role of proteins on a biological process, investigating the effects of different drugs on disease states or figuring out how different traits are passed down to offspring.  To answer their questions, scientists often turn to model organisms that have physiological and biochemical similarities to humans.  You may have heard of scientists using mice or worms, but have you ever heard about scientists using squids?

The Hawaiian bobtail squid is a master of camouflage and pulses with bioluminescent microbes. https://commons.wikimedia.org/wiki/ File:Hawaiian_Bobtail_Squid.jpg (Credit: Narrissa Spies).

Squids are a member of the class cephalopoda, which includes animals like the octopus or cuttlefish. Squids come in all shapes and sizes and can perform some really cool tricks!  Firefly squid, for example, are bioluminescent, which means they can produce light using special organs on their bodies called photophores.  The colossal squid is thought to be the most massive of all the squids and can weigh more than a polar bear!  Some squid species have started to break into the scientific spotlight by virtue of their more mysterious characteristics, like tentacle regeneration.  Squids are also valued for their complex nervous systems and brains. In fact, a squid was used to prove that nerve cells produce electrical pulses, and this discovery was so important that the scientists involved earned a Nobel Prize!  A fun use of a complex nervous system can be observed in Caribbean reef squid.  These squid are able to change their colors and patterns with the help of nervous-system controlled chromatophores.  These color and pattern changes allow the squid communicate with each other and help them hide from predators!

A giant squid axon. https://www.flickr.com/photos/historyatnih/14356033761 (Credit: NIH History Office)

More recently, scientists have been using squids to conduct research on the microbiome and brain diseases like Alzheimer’s. Larger squids are particularly useful in research about the nervous system and brain because they have large nervous system cells that scientists can easily manipulate.

In addition to their more natural characteristics that lend themself to scientific inquiry, researchers have begun to experiment on squids in less natural ways. If you’ve ever heard of gene editing, you’re probably familiar with CRISPR-Cas9, which is a tool used to manipulate DNA. Scientists recently proved that CRISPR-Cas9 could work in squids by using the gene-editing technique to delete the gene TDO, which is responsible for pigment formation in the squids. As a result, the squids that were edited by CRISPR-Cas9 were as clear as glass! 

Scientists used the longfin inshore squid, pictured, to knock out the gene responsible for causing the red pigmentation seen dotting the squid’s body.  https://www.flickr.com/photos/noaaphotolib/5187513523 (Credit: SEFSC Pascagoula Laboratory; Collection of Brandi Noble, NOAA/NMFS/SEFSC.)

Squids are fascinating organisms that should not be overlooked. Although the use of CRISPR to make squids clear may seem trivial, it proves that their DNA can be manipulated. Combine this new technology with the squid’s nervous system and complex brain, and scientists could have a new organism in which to manipulate the brain and model human disease! What would you choose to study with the squid as your model organism?

Edited by Zoe Terwilliger and Meryem Ok