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Life on Earth has always been shaped by other bodies in space, and life in our oceans is especially susceptible to interactions that have huge effects on life as we know it!

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Our rocky planet is a great place for life, but we can't give it all the credit. Life on Earth has always been shaped by other bodies in space.

Thanks to the Sun and Moon, we have important cycles like days, seasons, and tides—and we have meteors and asteroids to thank for helping deliver our planet's water. But those aren't the only ways these celestial objects influence life on our planet—and life in our oceans is especially susceptible to their meddling. For example, whales seem to be sensitive to activity in the Sun.

For years, researchers were trying to figure out why whales that seemed perfectly healthy kept getting stranded on beaches. Early studies pointed to human activities like shipping, which generate massive amounts of noise underwater. They thought the whales might be getting disoriented because they were overloaded with sound.

Then, a 2020 study that looked at gray whales suggested that another reason they're getting stranded is because solar storms are messing with their ability to sense Earth's magnetic field. Solar storms happen when the Sun releases huge amounts of energy in a burst of charged particles that radiate outward. During severe storms, these charged particles rain down on Earth's magnetic field and can make it change in shape.

For humans, that's bad news because it can mess with communications and produce electrical surges in our power grids. But scientists suspected that it might also interfere with whale navigation, since they were pretty sure whales relied on magnetic fields to get around. To find out, researchers compared 31 years' worth of data on gray whale strandings and solar activity—and, sure enough, the most strandings happened during times with lots of solar storms.

So they think that outbursts from the Sun are getting in the way of whale navigation—which backs up the idea that whales are using magnetic navigation to get around the globe. And it could also give us a starting point to explore how solar activity affects the navigation of other creatures on Earth. But interactions with celestial bodies aren't all disruptive.

In some cases, they can be really helpful. For instance, the Moon appears to play a big role in the development of a reef-dwelling fish called the common triplefin. We don't know a whole lot about these baby reef fish, because they're tiny and hard to track.

But we do know that as babies, common triplefins trek out to the open ocean and spend at least 51 days there before moving on to full-time life on the reef. The thing is, the journey to and from the reef is not especially safe for baby fish, so scientists wondered why they would have evolved that strategy. In a 2018 study, they hypothesized that moonlight in the open ocean might be helping the fish track down the food they need to grow into adults—since the open ocean would be better lit than the shadowy reefs.

To investigate, they studied a structure in the fish's inner ear called the otolith. All fish have this structure, and it's useful because it lays down growth rings, kind of like a tree. So, by examining it, scientists can see how the fish grow over time.

In this study, researchers examined the otoliths of more than 300 adult triplefins. They looked at how patterns in the rings lined up with the lunar cycle and weather conditions to see what factors influenced their growth. And they found that when the triplefins were babies, they grew faster during bright, moonlit nights.

The researchers believe that brighter moonlight helps the baby fish see at night, so they can hunt more plankton—and pack on the pounds. They also think the Moon might help the baby fish relax—because their predators are hiding from their own predators on bright nights, so the triplefins have less to look out for! While the Moon is helping baby fish to grow, meteors are fertilizing the growth of phytoplankton.

These are tiny plants that make up the base of the entire ocean food chain. And to grow in large numbers, they need some help from outer space. See, these tiny organisms rely on a bunch of dissolved nutrients, like nitrogen, phosphorus, and especially metals, like iron.

But dissolved metals are often in short supply. Like, they're around a thousand times less concentrated than other nutrients—and that puts a limit on the amount of phytoplankton that can grow. Which could put these organisms in a tight spot in remote places like the Southern Ocean, where there's not a lot of dust blowing off the land to put iron in the sea.

That's where meteors come into the picture. Every day, thousands of mostly-small meteors burn up in the planet's atmosphere and turn into space dust. It's estimated that around 40 thousand metric tonnes of space dust accumulates on our planet each year!

And this dust is full of iron. Researchers estimate that in remote marine regions, space dust contributes up to 300 percent more iron than any other source, providing the nutrients phytoplankton need to thrive! Without the help of space dust, the ecosystems of far-flung locations would likely look completely different, with a lot less phytoplankton to fuel the food web.

So every day, along with driving the natural cycles living things depend on, objects in space are meddling with marine organisms in subtle ways that have huge effects on life as we know it. Thanks for watching this episode of SciShow Space! And if you enjoyed it, you might like our episode on eight truths and myths about the full Moon, which you can find right after this! {♫Outro♫}.