What Is Commensalism?

In commensal biological relationships, one organism benefits from another's work without harming (or, often, even alerting) the worker organism. Learn more about commensalism in this episode of BrainStuff.

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Episode Transcript

Speaker 1 (00:01):
Welcome to brain Stuff, a production of I Heart Radio,
Hey brain Stuff, Lauren Vogelbaum. Here in nature, there's a
certain ethos of all scratch ere back if you scratch mine.
Living things never exist in isolation, and organisms of different
species occasionally need to cooperate in order to get stuff done,

(00:22):
And sometimes one organism takes the benefit from another while
that other one blithely lives its life unharmed but blissfully
unaware of the service it's performing. Collegists call this form
of half passive cooperation commence all is um, and it's
different from some other ways that members of an ecosystem
can interact. For instance, commence allism isn't the same thing

(00:44):
as parasiteis m, where one partner the parasite lives on
or in the body of a host and only one
partner actually benefits while the other is harmed. It's also
not exactly the same as mutualism, where both partners benefit
from the partnership. But think about the relationship between bees
and flowers. Of the bee gets food while the flower
accomplishes its reproductive goals. Commence ali is um involves one

(01:08):
organism just going about its business while one or more
others called commence als just sort of hang out and
benefit from that one guy's hard work. We spoke with
Amanda Hips, director of Communications and Development at wild Landscapes International.
She said, one of my favorite commensal relationships is the
one of Eastern screech owls and blind snakes. The owls

(01:30):
bring live blind snakes to their chicks, while some of
the snakes are eaten. The lucky ones burrow into the
nest and eat insect larva that they find there, lava
that would likely parasities the chicks. A study by scientists
from Baylor University found the chicks who grew up in
nests with blind snakes grew faster and experienced lower mortality
rates compared to nests without blind snakes. We can observe

(01:53):
three main types of commence all is um in Quillinism
is when one species lives on or inside of another species,
the way that our gut bacteria live inside us or
within a nest, burrow or dwelling created by another species.
For instance, gopher tortoises, which are native to the southeastern
United States, did long burrows for shelter, some of them

(02:13):
reaching forty feet or twelve meters in length. Hundreds of
other animals have been recorded using these burrows. Some of
them have even evolved to require the burrows of the
gopher tortoise in order to survive. Most of the commence
als are insects, but these burrows are also important to
a variety of species of snakes, frogs, and small mammals.
Hips said, there are fourteen recognized insects that are fully

(02:37):
reliant on gopher tortoises. One of these species is a
moth that feeds exclusively on the keratin of the shells
of dead gopher tortoises. Some of the remaining insects feed
on gopher tortoise doung Others feed on pest flies or
other organic matter inside the tortoise burrows. I like to
think of them as a housekeeping service to the gopher tortoise.

(02:57):
Although the impacts they have on gopher tortoises is not
yet understood, they likely lower parasite loads for tortoises and
the other vertebrates that also take advantage of the burrows.
Another kind of commence all is um is called metabiosis,
wherein one organism unintentionally forms a habitat for another while
just going about its normal business. For example, maggots need

(03:19):
to live somewhere, and it's often on or in the
carcass of a dead animal that, to be fair, wasn't
using that carcass anymore. Similarly, the gilo woodpecker makes its
nest in the cavity of the saara cactus, and hermit
crabs protect themselves and the discarded shells of snails and
other gastropods that have outground them. Meanwhile, for a c

(03:40):
is a type of commence ali is um when one
animal attaches to another in order to catch a ride
from one place to another. For instance, a nematode or
might can't really get very far on its own unless
it climbs on board a bee or a fly. The
might or nematode gets a huge benefit from the exchange,
whereas the bee or fly doesn't really benefit or suffer
from the interaction. While commence all um is a huge

(04:04):
benefit for some of the organisms in the deal, it
can be really tricky for an ecosystem under stress. Hips said, Ultimately,
I think having more commence ali is um in an
ecosystem could make an ecosystem more vulnerable if you lose
one species you could lose another If gopher tortoises went extinct,
we will undoubtedly lose other species along with it. Today's

(04:29):
episode was written by Jescelin Shields and produced by Tyler Klain.
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