Despite being multicellular and photosynthetic, organisms such as kelp and sea moss are macroalgae, not plants, because they lack specialized roots and stems to pump water.

The world's largest species of marine algae is giant kelp, which can grow as much as two feet per day from depths of about 100 feet up to the ocean surface.

Algae can capture carbon dioxide at rates up to 50 times faster than land-based plants and can be grown in tanks that use one-tenth the land footprint of terrestrial plants.

Some organisms are composed of a single cell visible to the naked eye

By incorporating tough, cellulose-rich cell walls, rapid movement of molecules via cytoplasmic streaming, and other biological techniques, some unicellular organisms can bypass the physical limitations that restrict the size of cells. Organisms such as the Stentor coeruleus and Acetabularia can be seen without microscopes.

Molecules derived from algae can be found in foods such as ice cream, salad dressings, brownie mix, and gravies, as well as in products such as toothpaste, multivitamins, and egg substitutes.

Some algae have helped remove microplastics from water after being bioengineered to clump together with these contaminants, forming an easily collectible microplastic-algae sludge.

Scientists have collected critical minerals from ocean water using seaweed, a type of algae that leaves behind a mineral-rich powder called bio-ore after being processed into biofuels.

Green algae have lived on Earth for about one billion years, roughly twice as long as the first plants.

The cells of spotted salamander embryos and early-stage larvae harbor algae that support embryonic development by increasing oxygen levels and removing waste.

As of 2026, the Great Atlantic Sargassum Belt is the world's largest macroalgal bloom, with seaweed stretching from the Caribbean to West Africa.

Harmful algal blooms can occur in warm, nutrient-rich, stagnant waters and are often associated with the rapid reproduction of blue-green algae—a misnomer for cyanobacteria, not algae.

Massive blooms of microscopic algae called dinoflagellates produce the neon blue light seen in glowing tides.

Acetabularia jalakanyakae is one of the largest known single-celled organisms and is nicknamed the 'mermaid's wineglass' for its umbrella-shaped cap.

Deep water corals—located throughout the world's ocean basins at depths beyond 200 meters (660 feet)—slowly build small coral gardens in the dark with the help of underwater worms.

Coral reefs are built by thousands of coral polyps—tiny animals whose mouths both consume food and expel waste.

The term 'symbiosis' was coined during the study of lichens—composite organisms in which algae or cyanobacteria partner with a fungus, alongside bacteria.

View a gallery of diatoms—algae surrounded by glass-like shells—captured via microscope.

The Amazon rainforest is considered the 'lungs of the Earth,' but it contributes less than a quarter of the oxygen of phytoplankton—microscopic plants, algae, and bacteria capable of photosynthesis.

Over 1 million fish, marine mammals, and invertebrate species depend on coral reefs for habitats, camouflage, and food.

Meet siphonophores, breathtaking jellyfish-like organisms

Siphonophores are colonial jelly-like creatures made up of specialized segments that work together as one. They're fairly unknown despite being a significant sea predator. Sink into their strange beauty with this video.

Despite lacking a traditional nervous system, plants have specialized cells that help detect gravity, enabling them to identify which way is down to grow roots and which way is up to push shoots toward the surface.

About 1,500 species of tardigrades have been identified by their unique physiology

Freshwater-bound eutardigrades live on mosses and lichens and are distinguished by variations in the shape and number of claws at the end of their legs. Marine heterotardigrades, which live on algae and deep-sea sediments, have been observed to possess feathers, inflatable appendages, and flagpole-like tails.

Photoautotrophs, which include plants, algae, bacteria, and Euglena, are organisms at the base of the food web that convert light energy from the sun into chemical energy stored in sugars.

Cells are categorized by the presence of contained genetic material and other organelles

While prokaryotes contain one or more cells with free-floating genetic material in a region called the nucleoid, eukaryotes possess a nucleus specialized for DNA storage. Plant cells possess cell walls—a reinforced structure surrounding their membrane—made of cellulose, while fungal cell walls contain chitin. Animal cells have lysosomes housing enzymes that break down biomolecules. (Some readers may experience a paywall.)

Coral reefs get their colors from zooxanthellae—photosynthetic algae that line corals' digestive tracts and provide them with sugars in exchange for a home within this protective tissue.

An analysis of fossilized reefs from northern Africa and Germany suggests that shallow water corals and photosynthetic algae formed the mutualistic partnership seen today between 419 and 359 million years ago.

Watch underwater photosynthesis make water look like champagne

In shallow waters where sunlight can reach, photosynthetic reactions absorb water and dissolved carbon dioxide, producing bubbles of oxygen at the surface of plants. As these bubbles rise to the water's surface, a fizzy appearance is created.

As immobile animals, corals and the organisms that live on them have evolved a suite of chemical compounds to prevent disease and ward off predators they cannot outrun.

Some organelles are believed to have once been independent cells

Mitochondria and chloroplasts, which are both responsible for energy production in cells, have DNA distinct from that of their host cells and are surrounded by cellular membranes resembling those of bacteria. Through symbiogenesis, these and other specialized structures were absorbed into larger cells, forming the modern-day biological units.

Astronauts on the International Space Station have tested an algae-powered bioreactor that converts carbon dioxide, water, and light into oxygen and edible, protein-rich biomass.

Breaking down the challenges of alkaline environments and how extremophiles survive them

These areas are far less acidic than the interiors of most organisms' cells, and this imbalance draws protons that are needed for various metabolic processes, including energy production, out of cells. To counter these effects, some alkaliphiles have developed stronger proton regulation across their cellular membranes and proteins that drive these processes with greater stability amid such acidity imbalances.

Adhesion molecules and intercellular junctions allow cells to connect together

While some organic structures are mostly composed of non-cellular components (e.g., collagen and calcium phosphate minerals in bones), tissues and organs composed of connected cells rely on specialized proteins and connections to create watertight seals that protect cells within the interior from environmental molecules.

Stony corals form a type of calcium carbonate called aragonite from ions brought to the ocean by rivers that have broken down terrestrial rocks.

Cell theory originated from microscopic observations of cork and dental plaque

In the mid-1600s, Robert Hooke identified compartment-like structures—which he called cells—in cork, and Anton van Leeuwenhoek discovered bacteria in samples of his dental scrapings. Almost 200 years later, Matthias Schleiden and Theodor Schwann showed that plants and animals, respectively, are composed of cells, proving that cells are the foundation of all living things.

Watch how deep-sea mining equipment collects and processes polymetallic nodules—metal-rich, potato-shaped rocks—from the ocean floor and creates environmentally damaging plumes of sediments.

Explore a gallery of tardigrades

Although sometimes called moss piglets, tardigrades are most often white or clear with some dark pigments. Tardigrades only move by crawling, not swimming, and depictions of organisms with caved-in heads or other coloration result from sample preparation for microscopes.

Learn how chloroplasts—the photosynthesis factories—may have once been independent cells

Possessing DNA of their own that differs from that of their host cell and surrounded by cellular membranes like those observed in bacteria, chloroplasts are believed to have evolved from a cyanobacterial cell. The endosymbiotic theory explains that these organelles were absorbed into larger cells, leading to the photosynthetic cells seen today.

Plants use physical and chemical defenses to protect themselves

Tree bark is difficult to chew and resistant to pathogens, while the waxy cuticle on the surface of leaves deters insects and microbes. Some plants possess thorns, spines, and prickles to discourage predators. Plant cells can also produce antimicrobial toxins or release compounds to alert parasitic wasps to lay eggs in attacking insects.

Research suggests microplastics disrupt photosynthesis in plants and algae, and this damage in crops may already rival the impact of climate change on food supplies.

A chemical overview of water, whose uncommon properties help sustain life on Earth

The uneven distribution of charge in water molecules allows them to bond to each other and to surfaces, enabling them to move against gravity, including up plants through roots and stems. These bonds also keep water in a liquid state over a wider temperature range and make it less dense as it freezes. This causes ice to float and form an insulating layer for underwater ecosystems, from which all life originated.

Multiple species exhibit convergent evolution by developing crab-like features

Various organisms that appear to be different types of crabs, such as porcelain crabs and coconut crabs, have been shown to belong to distinct decapod lineages whose predecessors resemble shrimp or lobsters. Environmental pressures and other factors have caused these species to develop similar characteristics, which nature has shown are beneficial to survival.

Oxygen and nutrients are circulated in tardigrade bodies through physical movement

Rather than having a circulatory system, oxygen is directly absorbed through their skin and spreads through a fluid called hemolymph as tardigrades crawl. When molting to grow, they shed their outer skin and stylets—sharp mouth parts used to pierce prey—which are regrown in their salivary glands.

Mangrove forests can store up to four times as much carbon as other forests and protect inland areas through complex root systems that absorb wave energy and hold mud and soil in place.

Tardigrades average about half a millimeter in size, with rear legs used for grasping

Their physiology and size, which is even smaller in the tun state, allow them to be carried by the wind and latch onto moist surfaces. They have been found in ocean trenches approximately 5 kilometers deep and at altitudes of six kilometers in the Himalayas.

Watch tardigrade samples under an optical microscope

Tardigrade samples can be collected by gathering moss and submerging it in tap water for 24 hours. The moss should then be cut and drained with a mesh sieve, and the water should be collected. Samples are observable in the water between 10x and 40x magnifications.

The ‘humongous fungus’ may be the largest organism on Earth at more than 2,300 acres

Discovered in 1988, when it was only covering 400 acres, this massive colony of Armillaria ostoyae, based in Oregon, has taken hold among the tree roots of the Malheur National Forest. It consists of a vast network of unique long black filaments of fungal tissue called rhizomorphs that grow under the soil and infect tree roots, nourishing the fungus but killing the trees. Researchers believe this fungal growth dates back more than 8,000 years and currently weighs approximately 35,000 tons.

Organoids: 3D organs grown from stem cells in the lab

An organoid is a three-dimensional construct composed of multiple cell types that originate from stem cells that can simulate the architecture and functionality of native organs. One big benefit of these lab-grown organs is that drug candidates can be tested in model systems without needing live patients.

View the fluorescently stained internal structures of a tardigrade

The photograph won the Olympus Global Life Science Light Microscopy Americas regional award in 2019. Using chemicals from biofluorescent organisms, the image illuminates internal structures with multiple hues in an otherwise mostly colorless organism.

Why tardigrades are a model extremotolerant species rather than an extremophile

By expelling most of the water from their bodies, water bears assume a state resembling a dried-up cyst and can withstand extreme environments, such as arid deserts. But in this state and these environments, tardigrades cannot grow, reproduce, or perform other functions associated with life, unlike extremophiles like dry-loving xerophiles.

Fungi can cause disease, but they’re also our planet’s key decomposers

Fungi are their own taxonomic kingdom separate from flora and fauna, acting as the key decomposers and nutrient recyclers for our planet. Watch this video to understand the diverse types of fungi and the stages of the fungal life cycle. This video illustrates how fungi species may spread, eat nematode worms, damage nearby plants, and much more.

What do psychedelic plants look like?

Far from the drippy aesthetic often associated with psychedelics, the plants powering naturally occurring psychoactive experiences may not stand out as anything special. This database offers a visual guide to psychoactive plants and fungi. Clicking on the title of a particular plant, such as yerba mate, will bring up a secondary screen with various hyperlinked images, such as the plant itself, related botanical drawings, and molecular structures.