8 Unexpectedly Beautiful Sea Creatures

You've likely ogled at playful dolphins and majestic blue whales, but when is the last time you paid mind to the humble snail or mollusk? In 2019, a lobsterman in Maine reminded us of the lesser-known beauties of the ocean when he caught a rare cotton candy lobster, named and admired for its bright blue, pink, and purple shell. If a species as pretty as this is lurking in the water, what other beautiful sea creatures are out there?

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Nudibranch

black and green spotted sea slug on yellow and pick coral — Chriswan Sungkono / Wikimedia Commons / CC BY-SA 3.0

You probably know of nudibranchs by their informal name: sea slugs. These soft-bodied marine mollusks include more than 3,000 species and live in seas all over the world, from warm tropical seas to all three of Canada's frigid oceans.

Nudibranchs can be a variety of bright, beautiful colors and patterns. This is a defense mechanism because of their lack of shell. They resemble the plants around them to camouflage themselves from predators. National Geographic photographer David Doubilet once described them as "the high fashion models" out of all the sea creatures.

Additionally, bright colors scare away potential dangers as they generally signal that a creature is poisonous (even if it isn't). Amazingly, these animals can soak up their prey's pigment into their own tissue, which "allows them to be camouflaged while feeding atop the very animals they eat."

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Coconut Octopus

The coconut octopus is considered one of the most intelligent invertebrates in the animal kingdom. It impressively uses tools—such as coconut shells—to conceal itself and protect from predators. (You can see a fascinating demonstration of this self-defense tactic in the 2020 documentary film, "My Octopus Teacher," although that was a common octopus, not a coconut one.)

When it's not hiding in a self-made bunker, the coconut octopus is a beautiful sea creature. Its appearance is notable for its contrast between light and dark tones. The textured pattern of its main body is reminiscent of snakeskin, and light-colored suckers pop underneath the darker body as this cephalopod swims and even walks along the ocean floor. They are found in tropical waters of the western Pacific Ocean.

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Brittle Star

Closely related to starfish, brittle stars move briskly along the seafloor, thanks to long, slender arms. Their attractiveness can be attributed to their symmetry, with each arm protruding from a central disk.

Brittle stars, which are also known as serpent stars, are majestic and agile in their movement. They combine a graceful, snakelike quality with flexibility to pull themselves toward their intended direction.

They are also excellent multitaskers, with a five-jawed mouth and the ability to regenerate lost arms. They usually hide under rocks or in crevices during the day, venturing out to feed at night.

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Mantis Shrimp

Neither a shrimp nor a mantis, this stomatopod is only four inches long. With a long, colorful body and big, bright eyes, the mantis shrimp surely turns heads.

However, this sea creature is more dangerous than it lets on. It uses its tiny but powerful clubs to break the shells of its prey with punches with the force of a .22 caliber bullet. In fact, when being studied, scientists must keep mantis shrimp in thick plastic tanks because their powerful punches can actually break glass. Even the Guinness Book of World Records states that the mantis shrimp packs the most powerful punch of anyone in the animal kingdom.

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Leafy Seadragon

Though they may look like pieces of seaweed, the leafy seadragon is a fish more closely related to the pipefish than to a seahorse, though it's considered something of an intermediate between the two. Known as "leafies," these creatures are kings of camouflage, living among kelp and seaweed in the waters off south and east Australia.

The flowing protrusions may look like functioning appendages, but the leafy seadragon uses thin, nearly transparent fins to propel itself through the water. Most impressively, this beautiful sea creature has the ability to change color to match its surroundings for better camouflage.

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Flying Gurnard

The flying gurnard is most notable for its eye-catching "wingspan." Gurnards usually keep their huge pectoral fins held close against their body, but they flare out spectacularly when a predator is near. The transparency of the fins combined with the colorful blue spots that adorn them make this creature especially beautiful underwater.

While their name suggests that they fly through the water, flying gurnards are bottom-dwellers. Their large fins do little to help them swim—they don't soar so much as move in short bursts. The name gurnard is derived from the French word for "grunt," which is the sound made by their swim bladder as water moves through it. Flying gurnards grow up to 20 inches in length.

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Christmas Tree Worms

One look at a Christmas tree worm is all it takes to know where they get their name. These beautiful creatures are scattered throughout tropical oceans worldwide, but you'll most likely find them embedded in coral reefs. The feathery "crowns" that give them their distinct yuletide appearance act as both a filter for food and a harness for oxygen. Each worm has two.

Unlike their namesake, Christmas tree worms come in a variety of colors including red, blue, orange, and yellow. They can live for as long as 40 years, making them a much better investment than your typical Christmas fir tree. You only see the crown protruding from the coral, and when the worm gets startled, it retracts rapidly into its burrow. They're not very big—only about 1.5 inches in length.

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Enypniastes Eximia

bright pink transparent sea cucumber on black background — NOAA Okeanos Explorer / Wikimedia Commons / Public Domain

Despite being discovered in the 1880s, the enypniastes eximia was not caught on camera until 2017. This genus of deep-sea sea cucumber is unkindly called a "headless chicken monster" by scientists, and it has neither a true brain nor sensory organs. A better descriptor is the "swimming sea cucumber." Still, it plays a valuable role in filtering sediment off the ocean floor.

The colors of the enypniastes eximia vary from bright pink to reddish-brown. Notably, it is also transparent, which allows its digestive system to be visible. It's considered quite active for being a small, deep-sea creature, and it grows to a length of 9 inches.