When I’m out in the ocean, I’m obsessed by everything I see. I’m the woman in the boat who’s got her fish guide out to look up the names of any unknown fish while throwing out fun facts about the creatures I’ve already identified. Yet so much ocean life is so small, I might miss them entirely. I’m talking about plankton—the tiny plants and animals that make up 90% of the mass of all marine life in the ocean and play an extremely important role in the health of our planet.
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Plankton are the start of the ocean’s food chain. Phytoplankton (a.k.a. plant-type plankton) turn sunlight into energy via photosynthesis and are eaten by zooplankton (a.k.a. animal-type plankton), small fish and invertebrates. Zooplankton, in turn, become food for larger species like fish, whales or crustaceans. Phytoplankton also pump out oxygen and sequester carbon. Five hundred million years ago, a bloom of plankton created the breathable oxygen-rich atmosphere humans depend on today.
Despite being so crucial to life on this planet, plankton are best defined by their go-with-the-flow nature. An organism is considered plankton if it can’t swim or move against the forces of the ocean like currents and tides. That’s why the name comes from a Greek word meaning “drifter.” A vast diversity of life falls under the heading of plankton from krill to single-celled algae to the offspring of crabs to jellyfish. Each plankter (that’s actually the word for individual plankton) is unique, and today I’m going to introduce you to a couple of the wandering creatures.
Dinoflagellates
Dinoflagellates are among the most common type of plankton with more than 1,500 species living in our ocean. They are single-celled phytoplankton with flagella, thread like appendages that allow these microscopic organisms to move. These tiny organisms can be responsible for wonder and destruction in the ocean. If you’ve ever swum in a bioluminescent bay, the light you see is caused by dinoflagellates. The light may help distract or startle would-be predators. In addition, some species have symbiotic relationships, helping corals, jellyfish and other animals thrive.
On the flip side, dinoflagellates are largely responsible for deadly red tides. The term “red tide” comes from the pigment found in these tiny creatures and the color of the water when these blooms happen. When dinoflagellates grow uncontrollably, they can produce toxins and reduce the oxygen in the water leading to die-offs in the ocean. Red tides can cause health hazards for people on land and lead to the deaths of manatees, fish and other creatures in the ocean.
Baby Sea Creatures

My favorite activity growing up was tide pooling, but I never really thought about how many of the creatures I encountered ended up there in the first place. That’s because the offspring star fish, sea urchins, sea anemones, barnacles, crabs, even octopuses start their lives as plankton that look almost nothing like the creatures they will one day become. If you want to play the wildest game of “Where are they now?” try to match ocean creatures with their baby forms in this quiz from The American Museum of Natural History.
Siphonophores

There are about 175 different species of siphonophores, the most famous being the Portuguese Man-O’-War. Another notable siphonophore is the Apolemia, which may be the longest creature on Earth at 150 feet long. That’s about the length of 1.5 blue whales! Proof that not all plankton are the tiny creatures we commonly think of them to be.
While they may appear to be a single organism, they are actually a colony of individuals called zooids. Each zooid has a unique function in the colony. For instance, there are zooids that are responsible for swimming and moving around, while others specialize in digestion and providing food for the whole colony. There are even battle zooids that are always on the ready to inject toxins into prey.
Comb Jellies

When you think of plankton, you often think of tiny animals, not beautiful otherworldly creatures like comb jellies. They are mesmerizing to watch because they produce a dazzling array of colors. This effect is caused by their cilia, which are like little hairs and are what give the comb jellies their name. These combs diffract light, breaking it up like a rain droplet or prism, to create rainbows.
Despite the similar name, comb jellies are not types of jellyfish. In fact, they could be descended from the Earth’s oldest animals. Recent research suggests that they could be the closest relatives of the first group to split off from our common ancestor around 500 million years ago. Comb jellies are pretty simple creatures without intestines, lungs or stomachs but they do have a nervous system that has puzzled scientists. Comb jellies have a nerve net that doesn’t have the usual synapses that humans and most other animals need for their neurons to communicate. Comb jellies could hold the answers to so many questions we have about how life evolved on Earth.
Diatoms

Diatoms are single-celled algae and among the largest groups of life on Earth. You can find diatoms anywhere it’s wet: freshwater, the ocean, even in moist soil. There are more than 100,000 species of diatoms and counting, as scientists find new types every year. What each diatom has in common is a cell wall made of silica, the same component we use to make glass, meaning they literally live in glass houses. Silica is also the main component of opals, and diatoms share some of that beauty, earning the name “jewels of the sea.” Diatoms are not only beautiful but are also powerful. They produce a significant amount of the air we breathe and are critical to marine ecosystems all over the world.
Some of the most amazing creatures on Earth are the ones we can’t easily see on the surface. Plankton play a critical role in sustaining life on this planet. Climate change is causing disruptions that we can see like intensifying storms, but it is also causing issues that we can’t see. That’s why it is so important that we all do what we can now to reduce polluting carbon emissions that are changing the ocean’s temperature, chemistry and function. Ocean Conservancy views climate change as the greatest challenge facing our planet today and is committed to finding ocean-based solutions to address it. Join us in taking action to combat climate change now.
The post Five Types of Plankton appeared first on Ocean Conservancy.
Ocean Acidification
The Strata that Matta
From Desert to Seafloor

Fig. 1) team Strata That Matta: Victoria C., Maeghan D., Maddie B., Vale B. (from left to right)

The months leading up to OCEAN CORE Academy were filled with another type of adventure for me, surveying the badlands of New Mexico in search of dinosaur bones. Yet, my work in the Gulf Coast Repository consisted of examining ocean cores using a microscope. Although these experiences couldn’t be any more different, the two were similar in that each attempted to answer the same question: what did Earth look like in the past?
I focus much of my research on vertebrate paleontological and geological fieldwork, such as prospecting for fossils, measuring strata, or describing ancient paleoenvironments and faunal assemblages. While I knew about microfossils, I had not fully grasped how much geological history is present in them.
Fig. 2) fieldwork, NM (May 2026)
History Through a Microscope

This leads me to one of the most memorable parts of OCEAN CORE Academy, learning to prepare smear slides and identify what existed within the ocean cores. Ocean sediments are fairly recent in that they have not yet been lithified, each layer represents tens to hundreds of years of depositions onto the seafloor. What I looked at was much deeper!
It was a momentous occasion when I first saw a radiolarian beneath the microscope! These tiny fossilized organisms provide surprisingly detailed insights into ancient environments. The conditions in which different groups of microfossils thrive vary, but by tracking how they fluctuate between layers, we can reconstruct climatic shifts over geologic time.
Team Strata That Matta correlated a transition from calcareous to siliceous ooze layers with a cooling climate!
Fig. 3) my first time seeing microfossils

Fig. 4) radiolarian Fig. 5) coccolithophores Fig. 6) sponge spiccules
Bringing OCA Back to AZ
Upon my return to Arizona, I will carry this new perspective with me. As I move forward with future projects and field seasons in New Mexico, volunteer at the Arizona Museum of Natural History, and pursue my degree, the skills I developed here will prove to be invaluable for strengthening my own research.
Prior to attending OCEAN CORE Academy I viewed microfossils as existing, yet somewhat separate from my projects. This place has challenged that perspective. I came to understand that many of the most detailed records of Earth’s past are the microfossils hidden within a single grain of sediment!

Fig. 7) class of OCA 2026
Written by OCA 2026 student, Maddie Baare
Ocean Acidification
Earth’s History at Every Scale
From Desert to Seafloor

Fig. 1) team Strata That Matta: Victoria C., Maeghan D., Maddie B., Vale B. (from left to right)

The months leading up to OCEAN CORE Academy were filled with another type of adventure for me, surveying the badlands of New Mexico in search of dinosaur bones. Yet, my work in the Gulf Coast Repository consisted of examining ocean cores using a microscope. Although these experiences couldn’t be any more different, the two were similar in that each attempted to answer the same question: what did Earth look like in the past?
I focus much of my research on vertebrate paleontological and geological fieldwork, such as prospecting for fossils, measuring strata, or describing ancient paleoenvironments and faunal assemblages. While I knew about microfossils, I had not fully grasped how much geological history is present in them.
Fig. 2) fieldwork, NM (May 2026)
History Through a Microscope
This leads me to one of the most memorable parts of OCEAN CORE Academy, learning to prepare smear slides and identify what existed within the ocean cores. It was a momentous occasion when I first saw a radiolarian beneath the microscope!
Before, I had been hunting for fossils measured in centimeters/meters, but now I am studying those measured in micrometers. These tiny fossilized organisms provide surprisingly detailed insights into ancient environments. The conditions in which different groups of microfossils thrive vary, but by tracking how they fluctuate between layers, we can reconstruct climatic shifts over geologic time.
Using these changing microfossil assemblages, my team correlated a transition from calcareous to siliceous ooze layers with a cooling climate!
Fig. 3) my first time seeing microfossils



Fig. 4) radiolarian Fig. 5) coccolithophores Fig. 6) sponge spiccules
Bringing OCA Back to AZ
Upon my return to Arizona, I will carry this new perspective with me. As I move forward with future projects and field seasons in New Mexico, volunteer at the Arizona Museum of Natural History, and pursue my degree, the skills I developed here will prove to be invaluable for strengthening my own research.
Prior to attending OCEAN CORE Academy I viewed microfossils as existing, yet somewhat separate from my projects. This place has challenged that perspective. I came to understand that many of the most detailed records of Earth’s past are the microfossils hidden within a single grain of sediment!

Fig. 7) class of OCA 2026
Written by OCA 2026 student, Maddie Baare
Ocean Acidification
Microplastic Pollution Research at Sea
I have been studying plastic pollution for more than a decade. I’ve analyzed hundreds of samples in labs, pored over data and spent years thinking hard about where plastics go once they leave our hands and enter the environment. I love doing work on the water—this was a big part of my previous professional roles in Alaska and in Saipan, Northern Mariana Islands.
And here’s where it took me! I was thrilled to have the opportunity to join the first leg of eXXpedition’s voyage in the South Pacific this past spring, trading my lab coat for a lifejacket to study microplastics at sea. Sailing from Auckland, New Zealand, to the Bay of Islands aboard the 70-foot research vessel Wind Shift over 10 days, our crew of 12 women conducted ocean water-surface sampling via manta tow nets (a long cone-shaped mesh net), cleaned up debris on remote beaches and examined city streets with measuring tapes and field equipment. Our purpose? To collect key data to help us better understand the flow of plastics from land to sea.
Our all-female guest crew—hence the XX in “eXXpedition”—brought aboard expertise from the fields of structural engineering, circular economy strategy, sustainable fashion, plastics research, robotics and more. Together, we represented a remarkable cross-section of disciplines united around a shared concern for the health of our ocean.
Seeing it with my own eyes
We found plastics of all shapes and sizes everywhere we went—in the city streets of Auckland, while crossing the Hauraki Gulf and even at Aotea Great Barrier Island (one of the most remote and protected stretches of New Zealand’s coastline). Our ocean is vast and some of these places felt far removed from the centers of human activity, but this eXXpedition was a good reminder that plastic doesn’t respect remoteness. It moves, accumulates and shows up where we least expect.
Working alongside local NGO Sustainable Coastlines, we arrived on a remote stretch of beach on Aotea Great Barrier Island to audit and clean up any plastics we came across. What we found there told the same story our Auckland street surveys did: We found bottle caps, food packaging, fragments, plastic pellets and fishing debris. The everyday materials of modern life—but weathered, broken and scattered.
Science at sea
One of my favorite parts of the voyage (which was also one of the most challenging, if I’m being honest!) was the sea-surface manta trawl analyses we did onboard. I found out quickly that sorting microplastics from krill-laden seawater samples under a microscope while sailing is not for the faint of stomach.
The most common plastic culprit we found in those samples? Microplastic fibers. This type of microplastic is no wider than a human hair and is the most common type of microplastic found in the environment. Microplastic fibers can come from a variety of sources like cigarette butts, weathered ropes or wet wipes, but actually, most microplastic fibers shed from synthetic clothing and textiles. Laundering is a major source— shockingly, a single load of laundry can generate up to 18 million microfibers.
And yet, we found these tiny plastic fibers floating in the ocean many miles away from the nearest washing machine.
In my lab research, I have found microplastic fibers time and time again, but there’s something even more sobering about hand-picking them out of a seawater sample collected from pristine-looking waters. It was a good reminder of why understanding where plastic comes from, how it moves and where it ends up is so critical to addressing the problem at its roots.
Filter Out NSFW Microplastics
What I’m bringing back
Studying plastic pollution from the deck of a boat in some of the most remote waters in the Southern Hemisphere made me appreciate the work I do even more. It also made me appreciate how important people are in this giant puzzle of plastic pollution solutions. The plastic pollution crisis is a human problem, and solving it requires all of us. The courage and dedication of the women I shared those 10 days with is something I won’t forget. Going to sea, doing the science and pushing through discomfort to collect data that matters was not easy. We were seasick some days and exhilarated others. Despite that fact, we showed up for it fully, every day.
The plastic is out there, even in far-flung corners of the ocean. And the answer is not to be paralyzed by that fact, but to use it as fuel. Every sample we collected is now a data point in a larger story about where plastic comes from and where it goes. Every cleanup, every surface trawl, every street block walked and every hour spent at a microscope are parts of building the evidence base that informs policies, regulations and systems-level changes that can actually turn this crisis around.
Cleaning up beaches and coastlines is valuable and necessary work. But we also must stop plastic from entering the ocean in the first place—through stronger policy, better product design and real investment in waste management infrastructure everywhere. Luckily, when it comes to the most common microplastics in the ocean— microplastic fibers—there is already an effective, affordable solution to immediately reduce microplastics coming from our laundry by roughly 90%: washing machine filters. These filters act just like laundry lint filters in our dryers, capturing fibers in tightly-woven mesh and effectively preventing them from leaving our homes and leaking into the environment.
What can you do?
There’s no better time to tackle plastic pollution than right now, during Plastic Free July
! Take two minutes to add your name and call on your elected leaders to combat those pesky, dangerous microfibers that are pouring into our ocean daily—like the ones I found from my samples at sea. Together, we can stop plastic pollution at the source and protect our ocean forever and for everyone.
My biggest takeaways from this experience? People are remarkable. Our ocean is remarkable. And our ocean is worth fighting for, including from 70 feet of sailing vessel in the South Pacific, staring down a microscope with a pair of tweezers and a queasy stomach.
The eXXpedition South Pacific I voyage ran from April 27 to May 6, 2026, sailing from Auckland to the Bay of Islands. Learn more about the research team and our itinerary at https://exxpedition.com/voyage/auckland-to-bay-of-islands/.
The post Microplastic Pollution Research at Sea appeared first on Ocean Conservancy.
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