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Nemo, the adorable clownfish in the movie The world of Nemo, rubs on the anemone in which he lives to prevent him from biting and eating it as he does for most fish. According to a new study, this friction leads to the composition of microbes covering the clownfish.
Bacterial coagulation and anemones can help clownfish comfortably nest in the poisonous tentacles of anemones, a strange symbiosis that life scientists – now including a team from the Georgia Institute of Technology – are trying to understand. Marine researchers have studied microbes on clownfish mixed with deadly anemones.
"This is the iconic mutualism between a host and a partner, and we knew that microbes were present on every surface of every animal," said Frank Stewart, badociate professor at Georgia Tech School of Biological Sciences. "In this particular mutualism, these surfaces are covered with a substance that microbes love to eat: mucus."
Mucus swab
Clownfish and anemones exchange a lot of mucus when they rub. The researchers gathered clownfish and anemones and badyzed the microbes present in the mucus that covered them when they were hosted by anemones or when they were not there.
"Their microbiome has changed," said Zoe Pratte, a postdoctoral researcher at Stewart's lab and first author of the new study. "Two bacteria that we have followed in particular have multiplied on contact with anemones."
"In addition to that, there have been radical changes," said Stewart, the study's lead investigator. "If you looked at the total number of microbe bademblies, their appearance was quite different on a clownfish hosted by an anemone and on another one that was not."
The researchers hunted 12 clownfish in six aquariums for eight weeks to buffer their mucus and identify the microbes by gene sequencing. They published their results in the journal Coral reefs. The research was funded by the Simons Foundation.
Questions and answers
Here are some questions and answers about the experience, which have produced amusing anecdotes, as well as fascinating facts about anemones and clownfish. For example: fish that piss on anemones reinforce them. The clown fish changes gender. And it was particularly difficult to catch a fish that the researchers named "Houdini".
Does this solve the mystery of this strange symbiosis?
No, but it's a new approach to the fish-clown-anemone riddle.
"This is a first step that asks the question:" Is there a part of the microbial relationship that is changing? Said Stewart. The study provided the answer from the clownfish side, which was "yes".
An earlier hypothesis on the riddle badumed that clownfish mucus was too thick to sting. Current thinking considers that mucus exchange also covers clownfish with anemone antigens, ie its own immune proteins, or that fish and fish killer can exchange chemical messages.
"The anemone can recognize a chemical on the clownfish that prevents it from biting," Stewart said. "And that could involve microbes. Germs are good chemists.
In the future, researchers want to badyze the chemistry of mucus. They also do not know how the microbes present on the fish are changing because of the bacteria that the fish gleans from the anemone. It is possible that the fish mucus microbiome develops differently on fish due to contact.
What do anemones normally do to fish?
Kill them and eat them.
"The anemone has evolved to kill fish. He sends small darts of poison into the skin of a fish to kill him, then shoots him into his mouth, "Stewart said. "The clownfish gets out of it as it should."
By the way, tentacles are not harmful to people.
"If you touch an anemone, you'll feel like you're sucking your finger," said Pratte. "Their little harpoons have the impression of sticking to you. It does not hurt. "
What do anemones and clownfish remove from the relationship?
For starters, they protect each other from potential prey. But there are many more. Some clownfish even change bad by living in an anemone.
"When they start to be housed, the fish make a big change in development," said Stewart. "The first fish of a group that establishes in a wild transition anemone from a male to a female grows much larger and becomes the dominant member of the group."
She is then the only woman in a school of smaller male fellows.
Anemones appear to be growing and healthier, partly because clownfish urinate there.
"When the fish pee, the anemone algae will absorb nitrogen, then secrete sugars that feed the anemone and grow it," Pratte said. "Sometimes the fish drops its food and it falls into the anemone that eats it."
Fun anecdotes from this experience?
Many: It was a simple but laborious scientific process, partly because the researchers took meticulous care of the fish at the same time.
"Fish and anemones have to be paired, and fish can be housed elsewhere, like corners in the rock," said Pratte.
"Clownfish are smarter than other fish, so they are harder to catch, especially when we want to minimize animal stress," said Alicia Caughman, research badistant at the undergraduate Fast Track to Research program. from the School of Biological Science. "We named a fish" Houdini. "He could sneak between nets and tight spaces and be smarter than anyone else trying to catch him."
"We also had" Bubbles ", which blew a lot of bubbles," Biggie "and" Smalls "," Broad "," Sheila "," Earl "and" Flounder ", who liked to flap," Pratte said. Clownfish have different sizes and details in their bands, which allows people to distinguish them.
The problem of anemones of the microbial question may be more difficult to answer, because for all the tricks of Houdini, the anemones, which are spongy non-vertebrates, are even more painful. They can sneak into uncomfortable niches or plug the aquarium drainage. They also have microbiomes of temperament.
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