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World's most elusive giant squid could be monogamous, female corpse hints


By Stephanie Pappas 3 days ago

Squid was embedded with sperm from a single male.

A female giant squid caught in a net off Kyoto had dozens of sperm packets from a single male embedded in her muscles. (Image credit: Miyazu Energy Aquarium)

A female of the world's largest squid — sometimes called the "kraken" after the mythological sea monster — that was caught off the coast of Japan apparently had just one amorous encounter in her lifetime.

The female had sperm packets from just one male giant squid embedded in her body, which surprised researchers. Because giant squid are solitary creatures that probably run across potential mates only occasionally, scientists expected that females would opportunistically collect and store sperm from multiple males over time.

"We were almost confident that they are promiscuous," said Noritaka Hirohashi, a biologist at Shimane University in Japan. "We just wanted to know how many males are involved in copulation. So this is totally unexpected."


Related: Release the kraken! Giant squid photos


Mysterious mating

Hirohashi and his colleagues study reproduction and sperm biology in several squid species, but the most mysterious of all is Architeuthis dux, the giant squid. Rarely seen alive, the giant squid has a life cycle shrouded in deep ocean mystery. Video of living giant squid in their natural habitats has been captured only twice. The only thing researchers know about these mysterious creatures' mating habits is that female giant squid are sometimes found with large sperm packets known as spermatangia embedded in their muscles. Researchers writing in a 1997 paper in the journal Nature posited that male giant squid probably use their "muscular elongate penis" to inject the sperm packets into the females.

How sperm meets egg from there isn't entirely clear. It's possible that the female releases chemical cues that activate the sperm when she's ready to spawn, or perhaps she releases her eggs in such a way that they trail along the sperm packets as they leave her body. Squid females do have organs near the mouth called seminal receptacles, where some species storm sperm, and it's possible that in those species, the embedded sperm can travel over the skin to these receptacles.

Knowing that witnessing two giant squid mating is highly unlikely, Hirohashi and his team developed a window into the process, using genetics. Examining squid specimens from fisheries and museum archives, they pinpointed some segments of the giant squid genome that would distinguish one set of squid DNA from another. Think of it like a squid paternity test: Any sperm packets found on a female can be tested to see if they came from multiple males and, if so, how many.

The researchers are always on the lookout for sperm-spangled females. They send out flyers to local museums, fisheries and aquariums, asking them to alert the research lab if a giant squid specimen turns up. In February 2020, they got good news.

"In this case, we found [a] Yahoo News [article] telling that the giant squid was caught," Hirohashi wrote in an email to Live Science.

Saving sperm


The spermatangia, or sperm packets, embedded in the upper layer of muscle on the female giant squid. No one knows how the sperm get to the eggs to fertilize them. (Image credit: Miyazu Energy Aquarium)

The specimen was a female, with a mantle, or main body, 5.25 feet (1.6 meters) long. It was missing a pair of tentacles and one eye but still weighed 257 pounds (116.6 kilograms). The squid had been caught in a fisher's net in Kyoto and was displayed at the Miyazu Energy Aquarium before being dissected.


When Hirohashi's team examined the body, they found that the squid was just reaching maturity and that it had squiggly spermatangia 3.9 inches (10 centimeters) long embedded in five separate locations: three places on the squid's mantle, one by an arm and one on the head. Each location hosted at least 10 spermatangia. Some were near gashes that may have been caused by a mating male's beak.


Genetic analysis of the spermatangia revealed that each and every one came from the same male. This was shocking to the research team; giant squid are often found bearing sperm packets, in a way that suggests that males aren't particularly picky. Spermatangia have been found on immature females, perhaps as a way for males to make their sperm available after the female matures, and even on males, perhaps because males are willing to try anything (or perhaps because they sometimes accidentally self-fertilize). All of the evidence pointed to a species that would mate first and ask questions later.

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The specimen, of course, is just one female, so more research is needed to see if monogamy is the norm among giant squid females. It's possible that this female had simply only encountered one male before she was entangled in the net that ended her life, the researchers wrote in the September issue of the journal Deep Sea Research Part 1. Or perhaps it is typical for females to mate with just one male. The gashes might be part of the males' strategy for ensuring other males don't move in, perhaps by limiting a female's life span after mating so that she doesn't have time to collect more sperm. Or, the researchers speculated, the aggression and injuries could spur the females to mature and spawn so that the sperm is speedily fertilized.

The next step is to study the spermatangia of more specimens, Hirohashi said. And researchers need to figure out how the stored sperm reaches the eggs, which are not deposited particularly close to the spermatangia. Researchers also need to figure out basically everything else about this elusive creature, including its life span, migration and habitats, he added.

"Kids ask these questions at the aquarium, so we must answer," Hirohashi said.

Originally published on Live Science

Rare Bigfin Squid in Australian waters

Scientists record some striking footage.

Australia is home to a host of weird and wonderful creatures, and now it can add the rare Bigfin Squid to its inventory.

Credit: Matthew Marrison (MNF)

Scientists aboard a deep-sea research voyage led by the national science agency CSIRO have recorded five individuals in the Great Australian Bight at depths of up to three kilometres.

It’s a first for Australian waters, and one of only a dozen confirmed sightings worldwide.

Alongside its large fins, the appropriately named Bigfin Squid (family Magnapinnidae) has striking long arm and tentacle filaments.

“Differences in their appearance meant we were able to confirm they were five separate individuals, rather than the same squid multiple times, and although the surveys covered a relatively large area, the squid were actually found clustered close together,” says marine scientist Deborah Osterhage.

From the recordings, the team was able to measure the length of one squid, finding its tentacle filaments were more than 11 times their body length.

They also observed their colours and behaviours, including filament coiling behaviour which has not previously been seen in squids.

The findings are reported in the journal PLOS ONE.

Five Enormous Rarely Seen Squid Have Been Spotted In Australian Waters


THIS FLOCK OF NOODLES HAS NEVER BEFORE BEEN SEEN IN AUSTRALIAN WATERS. 

CSIRO, OSTERHAGE ET AL. PLOS ONE, 2020

By Rachael Funnell11 NOV 2020, 19:00


The ocean is home to some absolute whoppers and some of the largest creatures are also the most elusive. One such giant is the bigfin squid that belongs to the family Magnapinnidae, a group of deep-sea squid with large fins and long, noodly arms and tentacles. It has only been spotted in the flesh on a handful of occasions. Now, new research published in the journal PLOS One details the incredible discovery of five bigfin squid in the Great Australian Bight, the first time they’ve been seen in Australian waters.

Previous reports of these ocean giants have always been of a single individual, so to capture five of these on camera was a big deal for the team from Australia’s national science agency, CSIRO. Though they weren’t spotted all at once, the bigfins have small differences in their appearance, which made it easy for the team to recognize they were five different animals and not just one camera-hungry squid. All five were seen at depths of 2 to 3 kilometers (around 1.5 miles) over a 25-hour period but were within 300 meters (984 feet) of one another, constituting a veritable crowd for an animal that’s never been seen with a party of more than one.

Bigfins have modestly sized bodies compared to their incredible long tentacle filaments. Osterhage et al. (PLOS ONE, 2020) 

VIDEO https://www.iflscience.com/plants-and-animals/five-enormous-rarely-seen-squid-have-been-spotted-in-australian-waters/

The first-of-its-kind discovery offered a unique opportunity to shine some light on these creatures of the deep, and the team were able to get an accurate reading on their size for the first time. Previous in-situ attempts to measure them have involved using nearby objects of known length, such as the arm of a submersible, but this new research used lasers to get a more accurate picture of their size. The results? The largest individual was over 1.8 meters (almost 6 feet) long with a maximum tentacle length of almost 11 times its body size. The animal was mostly white at the tips of its arms and tentacles but was sporting a mix of brown, orange, and pink hues towards its upper limbs, mantle, and fins. The researchers also spotted a behavior never before observed in squid, as a bigfin adopted a raised arm posture known as the ‘elbow’ pose.


“We filmed the five bigfin squid in depths of 2 to 3 kilometers using a towed camera system and remotely operated vehicles (ROVs),” said marine scientist Deborah Osterhage from CSIRO in an email to IFLScience. “We were doing image-based surveys to find out more about the deep-sea environment in the Great Australian Bight. The first two were seen in the towed camera footage when it was watched back onshore in the video lab. We recognized them as bigfin squid and knew how rare it was to see them, so in the subsequent ROV survey we really kept an eye out for them. We were lucky enough to see three more and were able to watch in real-time on the ship while the ROV filmed them — pretty exciting!

“Little is known of bigfin squid, and many other deep-sea cephalopods, largely due to the inaccessibility of their vast yet little explored deep-sea environments and there is much more to learn about the deep-sea and the incredible animals that live there. So, for bigfin squid we need to wait for more sightings, or more ideally an adult specimen in good condition — which has never been collected before.”

Multiple sightings of mysterious bigfin squid documented in the Great Australian Bight

by Bob Yirka , Phys.org

Sighting 3: ROV images of a Magnapinna squid at a depth of 3060 m. (A) Close view of the Magnapinna squid encountered 5.3 m above the seafloor with proximal arms/tentacles seen slightly opened and fins undulating slowly. (B) Full extent of arms/tentacles, the longest being approximately 1680 mm. Credit: PLOS ONE (2020). DOI: 10.1371/journal.pone.0241066

A team of researchers from the CSIRO Energy, Commonwealth Scientific and Industrial Research Organization and Museums Victoria has documented multiple sightings of bigfin squid in the depths of the Great Australian Bight. In their paper published in PLOS ONE, the group describes their study of the unique creatures and what they learned about them.


Bigfin squid live deep in the ocean and are noteworthy for several reasons. The first is that they are rarely seen in the wild—researchers have documented just 12 sightings. They also have unique fins that jut out from the side of the head at an angle that resembles Dumbo's ears—and they serve the same purpose, though in the water instead of the air. They also have long tentacles that are multiple times longer than their bodies. And they live thousands of meters deep in the ocean.

Because of their remoteness, little is known about the bigfin squid other than their general physical attributes. This sighting is the first in the Great Australian Bight (the huge open bay on the country's southern coast). Additionally, this is the first time the squid has been observed in a group of sorts. Though hundreds of meters apart, they were apparently sharing parts of the ocean. Squid are typically loners.

Another first was taking laser measurements of one specimen: a bigfin squid with a body (mantle) that was 15 centimeters long. More impressive were its tentacles, which were measured at 1.8 meters. All previous measurements of bigfin squid had been estimates based on background information such as other fish in the vicinity.


PlaySighting 5 of Magnapinna sp. in the GAB. This video was taken by ROV on 25 March 2017 at a depth of approximately 3056 m. Blue boxes are present in the lower corners to mask embedded logos in accordance with publishing requirements. Credit: PLOS ONE (2020).

 DOI: 10.1371/journal.pone.0241066

The researchers found the squid while they were conducting underwater surveys in the Bight. When they came across the first specimen, they deployed further tools to get a better look. They used both remotely operated underwater vehicles and towed cameras. In all, they carried out over 40 hours of underwater observations at depths ranging from 950 to 2400 meters below the surface—and wound up getting footage of five of the rare squid.


Explore further  Did a shark clash with large squid and live to tell the tale?

More information: Deborah Osterhage et al. Multiple observations of Bigfin Squid (Magnapinna sp.) in the Great Australian Bight reveal distribution patterns, morphological characteristics, and rarely seen behavior, PLOS ONE (2020). 

DOI: 10.1371/journal.pone.0241066

Journal information: PLoS ONE

Revealed: The Mysterious, Legendary Giant Squid’s Genome

TOPICS:GeneticsMarine Biological LaboratoryMarine BiologyPopular

By MARINE BIOLOGICAL LABORATORY JANUARY 15, 2020

How did the monstrous giant squid – reaching school-bus size, with eyes as big as dinner plates and tentacles that can snatch prey 10 yards away – get so scarily big?

Today, important clues about the anatomy and evolution of the mysterious giant squid (Architeuthis dux) are revealed through publication of its full genome sequence by a University of Copenhagen-led team that includes scientist Caroline Albertin of the Marine Biological Laboratory (MBL), Woods Hole.

Giant squid are rarely sighted and have never been caught and kept alive, meaning their biology (even how they reproduce) is still largely a mystery. The genome sequence can provide important insight.

The giant squid has long been a subject of horror lore. In this original illustration from Jules Verne’s ‘20,000 Leagues Under the Sea,’ a giant squid grasps a helpless sailor. Credit: Alphonse de Neuville

“In terms of their genes, we found the giant squid look a lot like other animals. This means we can study these truly bizarre animals to learn more about ourselves,” says Albertin, who in 2015 led the team that sequenced the first genome of a cephalopod (the group that includes squid, octopus, cuttlefish, and nautilus).

Led by Rute da Fonseca at University of Copenhagen, the team discovered that the giant squid genome is big: with an estimated 2.7 billion DNA base pairs, it’s about 90 percent the size of the human genome.

Albertin analyzed several ancient, well-known gene families in the giant squid, drawing comparisons with the four other cephalopod species that have been sequenced and with the human genome.

She found that important developmental genes in almost all animals (Hox and Wnt) were present in single copies only in the giant squid genome. That means this gigantic, invertebrate creature – long a source of sea-monster lore – did NOT get so big through whole-genome duplication, a strategy that evolution took long ago to increase the size of vertebrates.

So, knowing how this squid species got so giant awaits further probing of its genome.

“A genome is a first step for answering a lot of questions about the biology of these very weird animals,” Albertin said, such as how they acquired the largest brain among the invertebrates, their sophisticated behaviors and agility, and their incredible skill at instantaneous camouflage.

“While cephalopods have many complex and elaborate features, they are thought to have evolved independently of the vertebrates. By comparing their genomes we can ask, ‘Are cephalopods and vertebrates built the same way or are they built differently?'” Albertin says.

Albertin also identified more than 100 genes in the protocadherin family – typically not found in abundance in invertebrates – in the giant squid genome.

“Protocadherins are thought to be important in wiring up a complicated brain correctly,” she says. “They were thought they were a vertebrate innovation, so we were really surprised when we found more than 100 of them in the octopus genome (in 2015). That seemed like a smoking gun to how you make a complicated brain. And we have found a similar expansion of protocadherins in the giant squid, as well.”

Lastly, she analyzed a gene family that (so far) is unique to cephalopods, called reflectins. “Reflectins encode a protein that is involved in making iridescence. Color is an important part of camouflage, so we are trying to understand what this gene family is doing and how it works,” Albertin says.

“Having this giant squid genome is an important node in helping us understand what makes a cephalopod a cephalopod. And it also can help us understand how new and novel genes arise in evolution and development.”

Reference: “A draft genome sequence of the elusive giant squid, Architeuthis dux” by Rute R da Fonseca, Alvarina Couto, Andre M Machado, Brona Brejova, Carolin B Albertin, Filipe Silva, Paul Gardner, Tobias Baril, Alex Hayward, Alexandre Campos, Ângela M Ribeiro, Inigo Barrio-Hernandez, Henk-Jan Hoving, Ricardo Tafur-Jimenez, Chong Chu, Barbara Frazão, Bent Petersen, Fernando Peñaloza, Francesco Musacchia, Graham C Alexander, Jr, Hugo Osório, Inger Winkelmann, Oleg Simakov, Simon Rasmussen, M Ziaur Rahman, Davide Pisani, Jakob Vinther, Erich Jarvis, Guojie Zhang, Jan M Strugnell, L Filipe C Castro, Olivier Fedrigo, Mateus Patricio, Qiye Li, Sara Rocha, Agostinho Antunes, Yufeng Wu, Bin Ma, Remo Sanges, Tomas Vinar, Blagoy Blagoev, Thomas Sicheritz-Ponten, Rasmus Nielsen and M Thomas P Gilbert, 16 January 2020, GigaScience.
DOI: 10.1093/gigascience/giz152

Study Reveals That Giant Squid Throughout the World Are Genetically Similar

TOPICS:Evolutionary BiologyGeneticsGiant SquidsUniversity Of Copenhagen

By UNIVERSITY OF COPENHAGEN MARCH 20, 2013

Study reveals that giant squid such as this one are genetically similar throughout the world. David Paul/Museum Victoria

In a newly published study, researchers examine the mitochondrial genome diversity of 43 giant squid samples collected from across the range of the species, finding that there is only one global species of giant squid, Architeuthis.

The giant squid is one of the most enigmatic animals on the planet. It is extremely rarely seen, except as the remains of animals that have been washed ashore, and placed in the formalin or ethanol collections of museums. But now, researchers at the University of Copenhagen leading an international team, have discovered that no matter where in the world they are found, the fabled animals are so closely related at the genetic level that they represent a single, global population, and thus despite previous statements to the contrary, a single species worldwide. Thus the circle, that was first opened in 1857 by the famous Danish naturalist Japetus Steenstrup as he first described the animal, can be closed. It was Steenstrup that realized this beast was the same animal that in the past gave rise to centuries of sailors tails, and even in more recent became immortalized by writers such as Jules Verne and Herman Melville, by demonstrating that the monster was based in reality, and gave it the latin name Architeuthis dux.

It was less than 1 year ago, that the giant squid, Architeuthis dux, was first filmed alive in its natural element. Taken at a depth of 630m and after 100 missions and 400 hours of filming, the footage was captured by a small submarine lying off the Japanese island of Chichi Jima – near to the famous Iwo Jima that was the scene of some of the bloodiest fighting between Japan and the USA in the Second World War.

Now, PhD student Inger Winkelmann and her supervisor Professor Tom Gilbert, from the Basic Research Center in GeoGenetics at the Natural History Museum of Denmark, Copenhagen University, have managed to place new bricks into the puzzle of this giant 10 armed invertebrate, that is credibly believed to grow up to 13 meters long and way over 900 kg.

And the two scientists conclusions are: No matter what a sample looks like, its one species all over the deep oceans of the planet.

Sinking to the depths

PhD student Inger Winkelmann says about these findings, that are published in the esteemed British journal, the Proceedings of the Royal Society B:

– We have analysed DNA from the remains of 43 giant squid collected from all over the world. The results show, that the animal is genetically nearly identical all over the planet, and shows no evidence of living in geographically structured populations. We suggest that one possible explanation for this is that although evidence suggests the adults remain in relatively restricted geographic regions, the young that live on the ocean’s surfaces must drift in the currents globally. Once they reach a large enough size to survive the depths, we believe they dive to the nearest suitable deep waters, and there the cycle begins again. Nevertheless, we still lack a huge amount of knowledge about these creatures. How big a range to they really inhabit as adults? Have they in the past been threatened by things such as climate change, and the populations of their natural enemies, such as the planet’s largest toothed whale, the sperm whale that can grow up to 20 m in length and 50 tons? And at an even more basic level…how old do they even get and how quickly do they grow?

The kraken and the seamonk

These new results about the mysterious giant squid are released, fittingly enough, on the 200th anniversary of the Danish naturalist and polymath, Japetus Steenstrup (born in 1813).

At the age of 44, in 1857, it was Steenstrup who saw that many of the monsters of sea-legend were related to fragments that he had been sent of what appeared to be a giant squid, and in doing so described the species for the first time and removed any hope that sea monsters such as the Kraken and sea-monk really existed (although nevertheless, similar monsters still inspired beasts in literature and even films throughout the 20th century, including Tolkein’s Lord of the Rings in 1957).

Professor Tom Gilbert, who lead the team that undertook the research, says:

– It has been tremendous to apply the latest techniques in genetic and computational analyses, to follow up on Steenstrup’s scientific research 146 years after he started it. But its also been a fantastic experience to work with the giant squid as a species, because of its legendary status as a seamonster. But despite our findings, I have no doubt that these myths and legends will continue get today’s children to open their eyes up – so they will be just as big as the real giant squid is equipped with to navigate the depths.

The work was undertaken in collaboration with researchers around the world, including scientists in Australia, New Zealand, Japan, Spain, Portugal, USA and Ireland.

Publication: Inger Winkelmann, et al., “Mitochondrial genome diversity and population structure of the giant squid Architeuthis: genetics sheds new light on one of the most enigmatic marine species,” Proc. R. Soc. B 22 May 2013 vol. 280 no. 1759; doi: 10.1098/rspb.2013.0273

Image: David Paul/Museum Victoria

SEE  https://plawiuk.blogspot.com/search?q=SQUID

SEE  https://plawiuk.blogspot.com/search?q=GIANT+SQUID

SEE  https://plawiuk.blogspot.com/search?q=KRAKEN

SEE  https://plawiuk.blogspot.com/search?q=CEPHLAPOD

 

Squid Fishing on the High Seas Has Exploded Since 2017

Global squid fishery shows how important it is to strengthen regional management of high seas resources

Squid jiggers use powerful lamps to attract squid to the surface. Simon Ager, Author provided

PUBLISHED MAR 12, 2023 5:20 PM BY QUENTIN HANICH, KATHERINE SETO AND OSVALDO URRUTIA

 

Global squid fishing increased by 68% between 2017 and 2020, according to our international analysis, prompting concerns that much of the international fishing fleet is sidestepping necessary conservation and management.

Our study, carried out with colleagues in Australia, Japan, the United States, Chile and Canada, and published today in Science Advances, reveals that almost all of the increase in squid fishing has occurred in unregulated areas, with 86% of squid fishing now occurring in places with little or no scrutiny of catch sizes.

Unregulated fishing poses a significant challenge to fishery sustainability and raises substantial equity concerns. While attention has tended to focus on illegal fishing, the growth in legal but unregulated fishing may pose an even bigger threat, particularly to species such as squid, whose fisheries can cover entire oceans.

To estimate the scale of global squid fishing, we analysed satellite imagery and vessel tracking data to see how many vessels are fishing for squid, and where and how often they operate.

Squid fishing vessels are typically outfitted with powerful lamps to attract squid to the surface. These lamps are so powerful that they are visible from space. This means we can use satellite data to spot these lights at night, along with data from the ships’ Automatic Identification System (AIS), which allows authorities to monitor the location and course of registered vessels.

Using this data, we estimate that the amount of light-luring vessel effort increased from an estimated 149,000 vessel days in 2017, to 251,000 vessel days in 2020. Of these, 61-63% were by vessels not broadcasting their AIS, and thus only visible by the loom from their lamps. This light-luring vessel effort represents an estimated total of 801,000 vessel days over the period 2017–20.

Finally, we correlated these data with national and regional management bodies, and determine how much of this activity is unregulated.

A complex problem

Regulation and management of globalised squid fisheries is complex, because this fishing takes place both in waters that are under national jurisdiction and on the high seas. Consequently, cooperation is fundamental to ensure fisheries are regulated at sustainable levels and avoid gaps or loopholes.

Regional fisheries management organisations have been established through international treaties to provide the framework for such cooperation, and to regulate so-called “transboundary” fisheries. However, out of 17 such organisations in existence, only two – the North Pacific Fisheries Commission and the South Pacific Fisheries Management Organisation – have dealt with squid fisheries. This means there are still large gaps in the Indian and Atlantic oceans.

Furthermore, it is not enough to create a regional fisheries management organisations; parties must also ensure the organisation actually adopts regulations. The United Nations’ International Plan of Action to Prevent, Deter and Eliminate Illegal, Unreported and Unregulated Fishing defines unregulated fishing (among other things) as that which occurs “in areas or for fish stocks in relation to which there are no applicable conservation or management measures”. Regional fisheries management organisations must do more than simply exist or adopt general measures if their fisheries are to be considered regulated.

What we found

Our analysis defines “regulated” fisheries as those within the exclusive economic zones of coastal countries, or within regional fisheries management organisations that have implemented specific conservation and management measures for squid stocks. In contrast, we define “unregulated” fisheries as those on the high seas where there is no such organisation in place, or where the relevant organisation has failed to adopt regulations pertaining specifically to squid stocks.

Using satellite imagery, vessel tracking, and data monitoring, our study found that globalised light-luring squid fishing fleets are truly global in scope, fishing across multiple oceans within a given year, moving freely between regulated and unregulated spaces, and catching vast amounts of squid with little or no oversight. Often, there is no requirement to report their catches to anyone other than their flag nation, with little or no independent verification.

Globalized squid fishing vessel connectivity. The number and size of circles corresponds to the vessels that fished in each ocean region (NW Pacific Ocean- purple; SE Pacific Ocean- teal; SW Atlantic Ocean- green; NW Indian Ocean- pink). The width of white connecting lines and numbers correspond to the vessels that were observed in both regions connected. Citation forthcoming

Unregulated spaces are often directly adjacent to regulated ones, and different fleets often target the same fisheries. This creates equity concerns for coastal communities that rely on species targeted by large industrial fleets, and for the governments of developing nations that depend on revenue from stocks that move between regulated and unregulated areas.

Furthermore, many of the fishing vessels carrying out unregulated fishing stay at sea for exceptionally long periods (months to years), often refuelling and offloading their catches to other vessels while still at sea, and thus avoiding the oversight that accompanies port calls.

Like all activities that draw on global resources, fishing on transboundary stocks should be fully regulated. Yet the regional bodies with the competence to adopt management measures are often restrained by distant water fishing nations that stall or oppose conservation and management measures.

The global squid fishery shows how important it is to strengthen regional management of high seas resources and to continue international calls for states and regional bodies to take this challenge seriously. These fisheries are ultimately shared by us all, yet few receive any benefit, and nearby countries’ own fish stocks are sometimes unfairly depleted.

Furthermore, the trans-oceanic nature of these fisheries highlights the crucial importance of comprehensive data-sharing agreements between regional fisheries management organisations for improving understanding of the movements of these vessels, and quantifying their impacts on squid stocks.

Quentin Hanich is a Professor at University of Wollongong.

Katherine Seto is a Research Fellow at University of Wollongong.

Osvaldo Urrutia is an Associate professor at Pontificia Universidad Catolica de Valparaiso.

This article appears courtesy of The Conversation and may be found in its original form here.

The opinions expressed herein are the author's and not necessarily those of The Maritime Executive.

Devils of the deep: How jumbo squids survive freezing cold, oxygen-deprived waters
August 26, 2020 12.25pm EDT


According to the Norse sagas, the kraken terrorized sailors off the coasts of Norway and Greenland. (John Gibson)

Humans are a picky species. We are happiest in a near-constant environment and experience severe and often fatal injuries if our core temperature falls below 25 C or if oxygen content of the air drops below 10 per cent.

Many other species, however, live in almost constant change.

Consider the red devil squid. Also known as the Humboldt or jumbo squid (Dosidicus gigas), it rises every night from the depths of the ocean for a few hours of frenzied feeding at the surface. Before dawn breaks, it leaves these warm waters and sinks back into the frigid abyss of crushing pressure and low oxygen.

As molecular biochemistry researchers, we wanted to know how squids adapted to daily changes in the environmental conditions imposed by their vertical lives.
Bears, tardigrades and krakens

Despite the obvious differences between one animal and the next, all animals share a considerable number of similar genes. According to a 2005 study, for example, the genome of the chimpanzee is about 96 per cent similar to the human genome.

The regulation of those genes allows animals to adjust to daily or seasonal changes, respond to environmental stresses or tolerate other stresses, such as extreme temperatures or pressures. Epigenetics — chemical marks that alter the availability of DNA — and RNA modifications, which can silence protein production, are two of the several ways genes are regulated.

Genetic regulation is behind the seasonal hibernation of bears, allows many species to survive in low- or no-oxygen environments and lets others withstand extreme dehydration. It even allows some creatures to endure the freezing, oxygen-deprived, radiation-filled vacuum of space, which may be happening now to the thousands of miroscopic tardigrades that crash-landed on the moon in 2019.

It turns out that is also how krakens survive in the abyss.
Krakens in the abyss

We began our study at Experiment, a platform for scientific discoveries, and crowd-funded the support we needed to work on the red devil squid in the Gulf of California, between the two Mexican states of Baja California Sur and Sinoloa.

On one tranquil, pitch-black night in the middle of the gulf, we noticed a flurry of movement around our boat. Jackpot.

A shoal of red devil squid were rising hundreds of metres from the ocean’s depths to the warm, oxygenated surface waters to join a large feeding frenzy. They mainly ate small fish but sometimes there was a bit of cannibalism.

Kenneth Storey with red devil squids during the research cruise in the Gulf of California. (Kenneth Storey), Author provided

Before the first rays of morning appeared, they began their quiet descent, where they would have to deal with oxygen deprivation (hypoxia), high pressures and near-freezing temperatures.

We successfully caught several juvenile and adult jumbo squid before they descended and placed them in sea-water tanks on the ship.

These aggressive two-metre-long predators calmly occupy the deep ocean by depressing global gene expression, essentially turning down the volume of most of their genome while activating a select number of genes that promote their survival. This is known as “metabolic rate depression,” and is the basis for the dormancy often associated with hibernation.

The central mechanism emerging as a vital driving force behind metabolic suppression and squid survival is epigenetics, or more specifically, the squid’s ability to alter its epigenetic code rapidly and reversibly.
Epigenetics of killer squid

Breaking down the word epigenetics helps reveal what it is. First, we have the Greek prefix epi, meaning outside of, over or around, and then we have genetics, which refers to the cell’s DNA code. So, epigenetics is the study of heritable and non-heritable changes that occur on top of or around DNA without altering the DNA sequence itself.

Squids rely on epigenetic mechanisms to survive environmental extremes and retreat into a state of suspended animation by slowing down their metabolic rate. They reduce the squid’s oxygen requirements, turn off non-essential biological processes and sidestep damage from cold temperatures.

The epigenetic tools that alter gene expression in both squids and humans include DNA and histone modifications, and microRNAs. Adding chemical groups (such as methyl groups) to DNA or histones (proteins that spool DNA) can alter the availability or function of the DNA, making it more — or less — available to the cellular machinery that converts DNA into proteins.
Epigenetic modifications can be initiated by a number of factors from environmental conditions to diet. They change the way genes are expressed. (National Institutes of Health)

While we have yet to explore the state of DNA modifications on oxygen-deprived squid, our study of squid histones shows that histones are modified to promote DNA condensation (or spooling), making DNA less accessible when the squid is deep in the ocean. This critical mechanism allows the squid to save energy while it is oxygen-deprived, as genes are turned off when they are tightly wrapped around histones.

A third mechanism that keeps squid metabolism flexible are microRNAs. These short pieces of RNA do not code for proteins, but silence genes by physically binding to gene transcripts and blocking them from being translated into protein.

We found microRNAs in the hearts and brains of red devil squid that could slow their metabolism while they were oxygen deprived, helping protect these organs from damage. In the muscles, which give squids the jet propulsion they need for daily vertical migrations and to escape from predators, we found another microRNA, expressed under low-oxygen conditions, that likely suppressed growth and energy use while the squid was in its metabolically depressed state.
A diver gets too close to a Humboldt squid (BBC Earth Unplugged)

These seemingly tiny changes have big effects, allowing the red devil squid to go back and forth from the surface of the ocean to its bottom, killing and eating everything in their path. But they also have implications for medicine, and can help researchers understand — and find innovative solutions for — health conditions like stroke, ischemia (inadequate blood flow and oxygen to organs) and organ transplants.

Nature has already solved a lot of the problems we face. We just need to figure out how.

Authors

Hanane Hadj-Moussa
PhD Candidate in Molecular Biology, Carleton University

Kenneth B Storey
Professor of Biochemistry, Carleton University
Disclosure statement

Hanane Hadj-Moussa receives funding from Natural Sciences and Engineering Research Council of Canada.

Kenneth B Storey receives funding from Natural Sciences and Engineering Research Council of Canada.

MUTUAL AID

Bioluminescent bacteria coordinate signaling to colonize squid’s light organ

Peer-Reviewed Publication

PENN STATE

 

IMAGE: NEW STUDY SHEDS LIGHT ON HOW BIOLUMINESCENT BACTERIA COORDINATE CELLULAR SIGNALING TO COLONIZE THE LIGHT ORGAN OF THE HAWAIIAN BOBTAIL SQUID IN A MUTUALLY BENEFICIAL RELATIONSHIP. view more 

CREDIT: MICHELLE BIXBY / PENN STATE

Bioluminescent bacteria and the Hawaiian bobtail squid have formed a longstanding mutually beneficial relationship. How the bacteria coordinate their behavior to colonize the squid—through cellular signaling and cues from the environment—is detailed in new study led by Penn State researchers.

A paper describing the study is available online in the journal eLife. The researchers also show that the mechanism that they describe is likely to be widespread in a broad array of bacteria and that understanding this coordination of cellular signaling will be important for understanding how bacteria colonize their hosts more generally.

“The bacteria we study, known as Vibrio fischeri, is associated with many different marine hosts, but its association with the Hawaiian bobtail squid is the best characterized,” said Tim Miyashiro, associate professor of biochemistry and molecular biology in the Penn State Eberly College of Science and the leader of the research team.

The squid have a specialized light organ tucked within the underside of their mantle that is occupied by the bacteria. The bacteria’s glow is believed to help camouflage the squid when viewed by potential predators from below. The bacteria, in turn, get nutrients from the squid to support their growth. The squid, however, are not born with the bacteria in their light organs. Bacteria from the environment must make their way into the light organ after the squid hatch.

“Aspects of bacterial behavior in the light organ have been characterized,” said Miyashiro, “but the cellular mechanisms that allow the bacteria to colonize the squid in the first place are still poorly understood, so we set out to investigate how the bacteria initiates colonization.”

Inside the light organ, bacterial behavior is coordinated through “quorum sensing.” The bacteria release signaling molecules that increase in concentration as the bacterial population grows and becomes denser. When enough bacteria are present—when a quorum is reached—a signaling pathway is activated such that the bacteria will begin to produce bioluminescence and their ability to move is suppressed. Prior to colonizing the light organ, the bacteria form large aggregates of cells as well, but if the quorum sensing pathway were activated they might not be motile enough to move into the light organ.

“So, the question is ‘how do the bacteria avoid the quorum sensing pathway when they form these large aggregates outside of the squid and instead initiate behavior that promotes colonization?’” said Miyashiro. “What we saw was that the aggregation pathway activates the production of a small RNA molecule that is normally repressed by quorum sensing. Therefore, when the signaling pathway that leads to aggregation is activated outside the squid, the RNA molecule is expressed, which enables the cells to bypass quorum sensing to remain motile and dark.”

The small RNA--called Qrr1—is part of the quorum sensing pathway that represses the ability of the bacteria to produce bioluminescence and promotes motility until a quorum is reached. When a quorum is reached, expression of Qrr1 is subsequently shut down.

“Qrr1 has also been shown to be important for promoting colonization,” said Miyashiro. “You might expect that Qrr1 would be repressed during aggregation like it is during quorum sensing, but that is not what happens. So, we performed a number of experiments aimed at characterizing the molecular control of Qrr1 expression during aggregation.”

The researchers showed that Qrr1 can be activated by a transcription factor—a protein that controls when and where genes are turned on in a cell--that also controls genes involved in aggregation. The transcription factor—a protein called SypG—is similar to the one used to regulate Qrr1 by the quorum sensing pathway This similarity enables SypG to promote expression of Qrr1 in the aggregates during colonization and ensures Qrr1 is not expressed once inside the light organ to allow bioluminescence.

“This complex regulatory architecture that controls Qrr1 expression allows it to play these two important roles and helps coordinate the shift in behavior from colonization to bioluminescence,” said Miyashiro. “When we look across the bacterial family that includes V. fischeri, we see very similar structures that suggest to us that this type of coordination is likely to be important for many symbiotic bacteria.”

In addition to Miyashiro, the research team at Penn State includes Ericka D. Surrett, graduate student in the biochemistry, microbiology, and molecular biology (BMMB) program; Kirsten R. Guckes, postdoctoral scholar in Miyashiro’s lab; Shyan Cousins, and undergraduate student; Terry B. Ruskoski, BMMB graduate student; Andrew G. Cecere, research technologist in Miyashiro’s lab; and C. Denise Okafor, assistant professor of biochemistry and molecular biology and of chemistry. The research team also includes Denise A. Ludvik and Mark J. Mandel at the University of Wisconsin-Madison.

This work was supported by the U.S. National Institute of General Medical Sciences, the Howard Hughes Medical Institute Gilliam Fellowship, and National Institute of Allergy and Infectious Diseases Fellowship. Miyashiro is a member of the One Heath Microbiome Center at Penn State and the Penn State Huck Institutes for the Life Sciences.

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JOURNAL

eLife

DOI

10.7554/eLife.78544.sa0 

METHOD OF RESEARCH

Experimental study

SUBJECT OF RESEARCH

Animals

ARTICLE TITLE

Two enhancer binding proteins activate σ54-dependent transcription of a quorum regulatory RNA in a bacterial symbiont