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Think of animals traditionally used in scientific research, and you probably think:
rats, mice, guinea pigs, fruit flies...
But there might be a new player in town,
and it’s one we’re more used to seeing at the raw bar than at the lab bench:
bivalves like mussels, clams, and oysters.
Animals that researchers use to help find answers to basic biological questions
are known as model organisms.
They’re generally chosen because their biology is well known
and they’re easy to care for in the lab.
Not only that though, we usually pick specific animals
because they resemble us in some key way,
so they make good models to help us understand more about ourselves.
There are already a few well-established model organisms
that might seem like bizarre choices compared to mice and rats:
things like ferrets, nematodes, and even sea urchins.
Bivalves may soon make this shortlist of favorite model organisms.
They meet the requirement of being easy to care for —
you don’t even need a supply of ocean water.
And it turns out there’s a lot they can tell us about ourselves.
In the last decade, researchers have been working hard to learn more about them,
and apply what they’re learning to improve our own health and wellbeing.
For example, bivalves have the potential to teach us a lot about how immunity works.
The ocean is positively crawling with viruses and other microbes.
And it’s not like bivalves’ shells keep the water out:
water supplies the oxygen and nutrients they need to survive.
Which means they are constantly encountering disease-causing pathogens —
for example, the microorganism that causes paralytic shellfish poisoning,
which you do not want to get! — but the bivalves themselves don’t seem to get sick.
And they do it without the help of antibodies.
Their immune systems can’t make them.
The adaptive immune system, which produces antibodies,
is something only vertebrates have.
Instead, as a part of their immune system, invertebrates like bivalves produce
chains of amino acids that have the ability to kill microbes —
earning them the name antimicrobial peptides, or AMPs.
These seem to be at least partly responsible for why bivalves can withstand
being constantly bathed in disease-causing microorganisms.
This is especially true for mussel: they have a huge variety of AMPs,
even compared to other bivalves,
which allows them to fend off many different pathogens and diseases.
Pharmaceutical companies are especially interested in studying mussel AMPs,
in the hopes that they might make good alternatives to existing antibiotics,
which is really important because we’re dealing a lot
with antibiotic resistance right now.
Additionally, learning more about the immune system strategies that have evolved in
bivalves could inspire new treatment options for all kinds of human diseases.
Speaking of immunity, several types of bivalves —
including clams, mussels and cockles —
are subject to a contagious form of cancer.
The cancer that they get typically spreads between animals of a single species —
but as researchers have dug deeper,
they’ve found that it’s also been able to spread between species.
In the past, contagious cancers were considered a fluke of nature, but now
researchers believe they could be more widespread than they originally thought.
The discovery of this type of contagious cancer has inspired scientists
to look into it as a model for human cancers.
They hope that understanding more about how it spreads between these animals
can help us understand more about how cancer spreads within our own bodies.
Finally, despite the obvious cosmetic differences, the way bivalves form their shells
can teach us a lot about how our bones are formed and repaired.
Nacre in particular is of interest to researchers.
That’s the iridescent layer lining bivalve shells —
the stuff that oysters use to make pearls.
Nacre from oyster shells has been used to help with the mineralization and growth
of bones in sheep, mice, rats and humans.
Basically, nacre stimulates bone-forming cells in the body,
activating the process by which bones grow and then fill in with minerals.
Along these same lines, it’s also been found to delay osteoporosis in lab rats,
through the activation of bone-forming cells.
Nacre may also help make bone grafts more compatible
with our bodies and immune systems.
Along these same lines, oysters have become a model to study tissue implants,
due to their pearl-growing abilities.
The pearl industry makes natural pearls by inserting a piece of tissue
from a donor oyster, along with a nucleus for the pearl to form around,
into the gonad of a recipient oyster.
This means that, much like a tissue implant,
the two genetically distinct tissues have to play nice.
But while implants are often rejected by the recipient, this is not the case in oysters.
Understanding more about these processes will help us improve
our implant and bone graft procedures to increase their success rate
and decrease the potential for rejection.
Bivalves are already being used as a model system in a lot of research,
but they’re not yet as established as model organisms like mice, rats, and fruit flies.
These creatures have extremely rich genomes, as they’ve evolved in an aquatic
environment with exposure to a lot of different environmental conditions.
We’ve only begun to scratch the surface when it comes to
understanding their genetics, which means there is lots of hidden potential
for innovating and improving upon our understanding of human health.
Model organisms are a huge part of how biology is done.
If you’re interested in even more insight into how scientific inquiry works,
you might like Brilliant’s course Scientific Thinking.
It’s designed to introduce you to the laws of physics without the number crunching,
instead demonstrating principles through puzzles.
And there are tons more courses on Brilliant, covering math, science,
engineering, and computer science.
Right now, the first 200 people to sign up at Brilliant.org/SciShow
will get 20% off an annual Premium subscription.
So check it out if you’re interested — and thank you for your support.
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