Stunning Underwater Plants and Sea Life on the Ocean Floor

The ocean is full of uncharted territory -- and of breathtaking natural wonders that look like they'd be more at home on another planet than in the blue depths just off the beach where you might vacation. These stunning underwater organisms offer an ethereal beauty hard to reproduce on land.

The vibrant hue of this lilac-looking purple coral isn't the only striking thing about it: Though the color is rare, this acropora coral is probably one of the most popular among sealife -- according to Animal World, acropora and monitor corals together comprise nearly 1/3 of reef-building species, which means they're often the first on the scene of a new reef, and they spread to provide homes for other corals. Photo via mattk1979 @ Flickr

With nearly 1,000 different kinds of sea anemone in the ocean, these creatures are responsible for some of the most stunning colors and shapes you'll find underwater. This species, the giant plumose anemone, can grow as high as three feet tall and thrives in cold water from Alaska to San Diego, reports Animal World. And while the soft pouf at the top looks like a nice place for a fish nap, those tentacles are the plumose's primary tool for stinging and catching prey. Photo via Animal World

The bushy red sea whip, also known as the finger gorgonian, is a fragile coral that, like other gorgonians, is most often seen in shallow water. Each branch contains countless coral polyps (which are small tubes fringed with tentacles) that are responsible for bringing in food. Photo via Aquacon

This emerald-colored sea anemone is a dead ringer for the land-based Anastasia flower, a type of spider chrysanthemum. Like other anemones, these attach themselves to hard surfaces -- like rocks and coral reefs -- to wait for fish that inadvertently swim into the stinging tentacles, according to National Geographic. Photo via poplinre @ Flickr

Only one kind of fish is immune to the stings of the anemone, as any kid who's seen "Finding Nemo" can tell you: the clown fish. Here, a black clown fish hides among the grass-like tentacles of a sea anemone. The relationship is beneficial to both creatures: The clown fish can keep the anemone clean by eating dirt that accumulates while scaring off predators, and the anemone acts as a safe space for the fish. Photo via Shek Graham @ Flickr

Despite its misleading name, sun coral are a species that don't require much sunlight at all: They can get the energy they need by feeding on plankton, and therefore make their homes in caves and other dark, underwater spaces, according to coral aquaculture lab Coral Morphologic. They're also the only stony coral that set up permanent digs in the Caribbean after invading the ocean in the ballast of ships coming from the coral's native ocean, the Indo-Pacific. Photo via laslo-photo @ Flickr

Feathery soft corals make up this bouquet of brightly-colored sea life. According to the University of California Museum of Paleontology, soft coral are members of the Octocorallia group, named for their "eightfold radial symmetry," which means they have eight smaller pieces that branch off of each main tube to give the downy appearance. Photo via Inon

Some of these life forms appear more familiar than you'd expect. Take this kelp, that looks like a leafy forest. Nutrient-rich kelp may show up on your beach as torn piles of seaweed, but underwater it has a whole different life: This plant, a type of brown algae, can grow from the surface down as far as 150 feet, where the darkness, still water, and variety of sea life that makes its home feels otherworldly. When scientists stumbled upon a new kelp forest in the Pacific Ocean in 2007, the discovery highlighted how much we still have to learn about the world's waters: According to NPR, biologists had previously thought that kelp couldn't grow in tropical waters. Photo via NPR/NOAA

The brain coral's name doesn't exactly make it sound like a pretty specimen of sealife, but these crater corals are popular in aquariums for their looks. Their skeletons create "miniature valleys with separate, pinched walls," which, according to Environmental Graffiti, is what reminds us of our own brains -- but they also come in bright colors from blue and red to pink and green. Photo by Mark Caruana via SaltAquarium.about.com

According to Ocean World, a coral reef can be home to as many different species and kinds of life as a rainforest -- which is part of why protecting them is so important. But these detailed and dramatic landscapes are threatened by pollution and overfishing, and at their current rate of destruction, we could lose 70 percent of the world's reefs in less than 40 years. Photo from the California Academy of Sciences via Ocean World