Lineages among oceanic squids which have been said to puzzle researchers for over a century have been resolved by scientists at NUI Galway (NUIG).
A team at the NUIG Ryan Institute has been able to name the different family groups and says this provides important clues as to how squid evolved.
The findings have been published in the Zoological Journal of the Linnean Society.
Lead study author Dr Fernando Angel Fernández-Álvarez at NUIG's School of Natural Sciences spent five years collecting tissue from squid during oceanic cruises and when sampling from commercial trawlers.
Oceanic squid on the bottom of the ocean floor with relatively close-up view of tentacles and suckers. Photo: NOAA OKEANOS Explorer Progra, 2013 Northeast U. S. Canyons Expedition
“The aim was to solve the relationships among this amazing group of animals. I believe this study is an important milestone for the field and a good starting point for performing in-depth studies on the evolutionary trends that shape the huge diversity of oceanic squids,” he said.
“Our research could also be useful as we try to understand how our oceans will respond to ever-increasing pressures from human activities,” he added.
The research team used a method known as genome skimming to reveal the full sequence of DNA and identify relationships among squid.
Each of the discovered groups was named based on the rules dictated by the International Code of Zoological Nomenclature, the team says.
It suggests that scientists will have a way to accurately identify and describe the biodiversity of these marine creatures in the future.
Oceanic squids are a highly significant part of the marine food web.
They are voracious predators and provide the main meal of toothed whales and other endangered megafauna.
They include the largest group of commercially fished cephalopods, the flying squids.
The researchers also discovered what they say are "unexpected and as yet, unexplained, relationships".
"For instance, delicate deep-sea glass squids are more closely related to powerful muscular Humboldt squids and to the unusual monogamous diamondback squid, than to other oceanic squids," the NUIG team states.
“How these remarkable changes in form came about is not yet understood," Prof Louise Allcock of NUIG's School of Natural Sciences, Ryan Institute, explained.
An oceanic squid resting on the seafloor, changing colour as it sits on its elbows to breathe. Photo: NOAA OKEANOS Explorer Program, 2013 Northeast U. S. Canyons Expedition
“Oceanic squids are an amazingly diverse group of cephalopods – molluscs with arms and tentacles like squid, octopus and cuttlefish - with fascinating adaptations to their watery environment," she said.
" For example, glass squids use their body cavity as a fluid-filled buoyancy chamber, while chiroteuthids develop fishing lures at the end of their tentacles," she said.
“This study also highlights the importance of public scientific collections in addressing long-standing scientific issues," Prof Allcock added.
"We supplemented the material we collected ourselves with samples from various museums including the Smithsonian Institution in the USA, the Biological Reference Collection of the Marine Science Institute in Spain and the Australian Museum, allowing us to have a truly comprehensive oversight of oceanic squids globally,“ she said.
The study was funded by the Irish Research Council through the Government of Ireland Postdoctoral Fellowship Awards.
Read the full study in Zoological Journal of the Linnean Society here
