A squid whisperer might be about to help revolutionise experimental biology.
Bret Grasse is one of the most renowned keepers and breeders of cephalopods, a group of animals that includes squid, cuttlefish and octopus, and his expert knowledge of these creatures may soon help biologists open up a whole new avenue of research.
Thanks in large part to his unique skills in rearing these animals, a major scientific endeavour to create a new line of animals for lab experiments is now becoming a reality, one that would unlock many of biology’s mysteries.
‘A global first’
In december, scientists at the Marine Biological Laboratory introduced the world to the first “cultured octopus laboratory organism” —pygmy zebra octopus (O. chierchiae)—following successful culturing methods for O. chierchiae that were developed at the University of Chicago’s Marine Biological Laboratory, under Grasse’s supervision.
They managed to breed the octopus through multiple generations, which they say is “a global first” and is critical for lab animals used in biological research because it “lets scientists study gene function and mutational effects from one generation to the next”.
This opens up “novel science that hasn’t been possible before,” the team says, meaning “the sky’s the limit” for what researchers want to do with these octopuses.
On the plus side, it means such creatures won’t have to be caught in the wild for experimentation anymore. But it also means that populations of this species that has so far enjoyed a free life in the wild, will now be kept indefinitely in captivity, purely as a new kind of lab rat.
I visited the lab in the earlier days of the project’s development, in 2017 and 2018, and spoke to Grasse and others about this project, its aims, and also about the ethics of turning what many consider to be advanced creatures into subjects for experiments behind the closed doors of research labs. Here’s what I learnt.
As a senior aquarist at Monterey Bay aquarium, in California, Grasse designed and developed the world’s first large-scale public exhibition of cephalopods.
“Cephalopods have been kept by public aquariums for many decades, but because of the difficult nature of keeping and breeding cephalopods no one has done it on a large scale before,” he told me in 2018. “Part of the R&D work that went along with that was trying to figure out how to optimise keeping these species, and how to perfect and refine breeding protocols and methods.”
The exhibit included multiple species with around 1000 individuals on display at any one time. “We were writing the book as we went along,” he says.
The success earned him accolades and renown, and he was recruited to run a facility dedicated to developing a cephalopod model organism at Marine Biological Laboratory in the coastal town of Woods Hole, Massachusetts, where he is currently manager of cephalopod operations.
Since April 2017, MBL has been trying to develop a new cephalopod model organism, that would expand scientists’ usual toolbox of animals for genetic research, which currently includes fruit flies and rats.
Because cephalopods are so advanced and yet so different to vertebrates, this would allow for studies of evolution of complex brains and social behavior than have so far been impossible, possibly yielding universal rules that govern aspects of development and behaviour.
One of the main challenges is to learn how keep these marine animals alive and happy enough to breed in a lab, and it’s Grasse’s expertise that has helped make this possible.
Floating and flashing
Most scientists worry about how many research papers they publish, but Grasse’s main worry is keeping his cephalopods alive and happy.
“Cephalopods are one of the few groups of animals that communicate with their skin and their body posturing, and based on those visual cues that I see from them, I can adjust our animal care practices, or our population dynamics or gender ratios—things of that nature,” says Grasse. “They give subtle cues with the coloration of their skin, and with very, very subtle behaviours, just the way they’re breathing or swimming or siphoning at one another or colour displaying at one another will signal, give me clues and allow me to proactively address these changes.”
By the time more obvious signs of stress or ill health emerge it’s often too late to save them, he says, so this sort of experiential knowledge is key to successfully breeding them.
For example, flamboyant cuttlefish are normally stationary at the substrate floor bottom. “When you see them floating around, or flashing colours in certain ways, those are direct indicators that they’re hungry or that something in that environment is stressful or suboptimal,” says Grasse. Similarly, if dwarf cuttlefish swim along the edge of the tank and breathe rapidly, that’s a sign they are hungry.
The team has honed in on a number of suitable species: small, with a short lifespan and predictable reproduction cycle. The list was reduced from an initial eight to a handful which are showing most promise, including species such as Hawaiian bobtail squid, two-spot octopus, flamboyant cuttlefish, striped pyjama squid, and dwarf cuttlefish.
Cephalopods have an extremely fast metabolism, requiring frequent feeding—and they need live food with high protein content.
Meeting the dietary requirements of different stages of development and moving them to larger tanks in good time as they grow is crucial. “Understanding specific species and their associated spatial and social dynamics is very important.”
Grasse says attention to detail matters, and that the tweaks he’s been making to parameters of water content and tank enrichment have already improved results: and have been able to obtain an egg survival rate of 90% or above for some species.
The team have also been periodically replenishing the stock with wild-caught animals to avoid inbreeding, which causes dwarfism and earlier maturing in some of these species. While these are precisely the characteristics that are good to have in a model organism, inbred animals don’t survive and breed well. In future, it might be possible to achieve this without the downsides of inbreeding to achieve a “perfect experimental model in cephalopods”.
“We’re not just keeping and breeding these animals, we’re hatching embryos and raising them to adulthood through multiple consecutive generations and in doing that we can alleviate some of the wild collection pressure to get those animals from the wild,” Grasse says. “And that way we can also have every life stage of every species we’re working with.” That means, he adds, that depending on the scientific question posed, the researchers can have exactly the kind of resource they need.
Which species might win out as the new model organism? Grasse hoped it would be the flamboyant cuttlefish, which is visually striking and played a role in launching his career at Monterey Aquarium as a key component of the large exhibit he put together. But his bet was on the bobtail squid, which already has a community of researchers studying it, or the striped pyjama squid, which seem to be the hardiest and also easiest to breed. So the eventual success with pygmy zebra octopus was somewhat unexpected—but no one knew at the time which ones would prove successful to keep and breed through several generations.
But despite the recent success with pygmy zebra octopus, the MBL is still prioritizing a different species to develop as a cephalopod research organism: the hummingbird bobtail squid (Euprymna berryi).
“We’re keeping the pygmy zebra octopus in our back pocket and will develop it as an octopus model only after we have worked out the kinks on our concentrated efforts to make the first cephalopod model, a squid, using E. berryi,” says senior scientist Joshua Rosenthal.
For researchers interested in ordering pygmy zebra octopus eggs for their studies, Grasse, says: “We hope to be able to provide cheirchiae eggs and individuals to the scientific community in the near future. Currently, we are optimizing our internal culture so we can offer this resource to others soon, but they are not currently available for purchase.”
Noriyosi Sato, Shimane University, Matsue, Japan, told me the project may provide a great contribution to evolution because cephalopods have many characteristic traits and it would be interesting to compare the findings to those from other model animals.
But he said that cephalopod cultivation will be tricky. For example, his team can see the mating and spawning behaviour of a small coastal squid (Idiosepidae, Sepiolidae) easily in tanks, but they don’t know what the para-larvae feed on, which makes it tricky to keep them.
Jennifer Mather, a cephalopod researcher at the University of Lethbridge in Alberta, also thinks it might prove hard to raise cephalopods in captivity. “I think they are a bit optimistic,” she said at the time of the MBL team. “But we shall see.”
Grasse promised to eventually share their findings and know-how with the wider community; the whole aim of the project is to provide the research world with a new resource to advance science.
The scientific value of model species notwithstanding, it’s hard not to think about the ethics of turning such charming and arguably intelligent creatures into ‘lab rats’.
And we know large parts of the public take a dim view of animal experimentation, especially with intelligent animals. Is it right, then, to keep cephalopods captive just to collect their eggs and experiment on them?
The question becomes more pressing after I visit the National Xenopus Resource at MBL, just across the road from the Marine Resource Center, where a somewhat dystopian vision of the future awaits. Here, I find tank after tank crowded with largely immobile frogs that have been raised here for many generations, over decades. They are pumped with hormones to make them lay eggs, and otherwise they just float in an utterly sterile environment.
It’s a far cry from their natural habitat and lifestyle in the wetlands of Nigeria—and also far from the public image of the center: in a nearby MBL accommodation center, Swopes, are two tanks with natural vegetation, rocks and only a couple of frogs sitting in each. At least a couple of other journalists find the visit uneasy, and it’s difficult not to think of the movie The Matrix, even if these are just unremarkable frogs, perhaps without much intelligence or any self-awareness.
“It doesn’t feel natural when you walk in there,” Grasse agrees. “You see these animals, with no habitat, they’re all mashed in there together: it doesn’t feel that good even though they probably don’t mind for all we know.”
A simple frog is perhaps a sacrifice worth making for advancing biomedical science. But what of the more advanced cephalopods?
“There is considerable research documenting the complex nature of octopuses and other cephalopods, suggesting that it’s time to let these sensitive beings live in peace,” Emily Trunnell, neuroscientist and PETA Research Associate told me at the time. “They have a will to live and be free, as evidenced by their reputation as skilled escape artists, and it is horrific to imagine the suffering these playful and charming animals would endure when restrained, poked, prodded, drugged and cut up in the name of ‘science’. Such research, it in its inherent cruelty and scientific uselessness, can never be justified.”
Instead, she said, research should turn to non-animal, human-relevant research methods, such as those using human induced pluripotent stem cells, microfluidic technology, bioprinting, and computer and mathematical modeling.
Others have less black and white views on the issue.
“My attitude to this is guided mostly by the animal welfare considerations,” said Peter Godfrey-Smith, professor in the School of History and Philosophy of Science at the University of Sydney. “Working on embryos is not a big problem, and a lot of very valuable developmental research can be done that way. So that would be OK with me, if the animals producing the embryos were kept in a good environment—an enriched one that gives them good behavioral opportunities, as well as providing basic needs.”
“What worries me a bit is a resurgence in neurobiological work on adult cephalopods,” he said. “There should be a reduction in scientific work that is primarily curiosity-driven and causes a lot of harm to the animal studied—I’d apply this to all animals that can very probably suffer, not just cephalopods.”
Mather thinks if the right species are chosen, whose ecology and natural history are well understood, and proper care is given, there should be no problems keeping them in captivity.
“The public has an understanding when they hear ‘experimental model’ that it’s going to be just dissected, brains pulled out and all this sort of thing,” Grasse says. In reality, a lot of research on genetic model organisms happens before embryos even hatch, and a lot of it is not invasive research.
He also says there is a danger of anthropomorphising octopuses and that there is no evidence that cephalopods feel pain.
To keep their animals happy, his team is providing natural habitats in the tanks, by mimicking conditions in the wild. As a result, the captive cephalopods here live even longer than in the wild. “There’re no predators, they have the habitat that they want, and they have a personal chef to bring them all the live food they want every day—so it’s actually a pretty good gig for them.”
And he says egg harvesting doesn’t seem to stress these animals, and they’re happy to go back to their normal behaviours. “Ethically we feel pretty good about it.”
I visited the MBL on two fellowships, one of which was funded by the MBL
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