Some of the most colorful sea animals that live beneath the waves are bright, beautiful ... and deadly
13 of the Most Colorful Animals of the Ocean
Updated on Jun. 06, 2025
Candy basslet (Liopropoma carmabi)
This secretive native of both sides of the Caribbean—from Belize to the British Virgin Islands—hides out on ledges and in caves of reefs up to 140 feet below the surface of the sea. Although not being spotted is tricky when you are lavender and orange striped with a bright blue tail!
Tunicate (Urochordata)
Also known as sea squirts, tunicates are barrel-shaped, often very vividly colored creatures. They’re members of the subphylum Urochordata, which attach themselves to rocks, docks and other stationary underwater objects. They feed by pulling seawater into their bodies, then siphoning out their all-time favorite meal: plankton.
Bluering angelfish (Pomacanthus annularis)
This almost neon-bright species, native to the Indian Ocean and West Pacific, loves to hang out in cloudy waters near piers and sunken ships. Growing up to a foot-and-a-half in length, an angelfish likes to feast on tunicates, sponges and zooplankton and often forms a bonded pair with a mate—which it greets after time spent apart with a little spinning dance.
Picasso triggerfish (Rhinecanthus aculeatus)
Looking like it originated in the mind of a cartoonist, this bad-tempered triggerfish hangs out—as do others of its ilk, of which there are 40 species worldwide—on the ocean floor. It digs out prey “such as crabs and worms by flapping away debris with [its] fins and sandblasting with water squirted from [its] mouth,” according to National Geographic. One of the most colorful sea animals, it can also “lock” itself into a crevice with its spines—an action unlocked by depressing another “trigger” spine.
Peacock mantis shrimp (Odontodactylus scyllarus)
This shrimp species inhabits the ocean flats of the Indo-Pacific, particularly around coral reefs. The males are multicolored, and the females, while just as bright, are usually monochromatic. According to Oceana, it has one of the fastest punches in the animal kingdom, which it uses to break open the shells of tasty snails, crabs and shrimp. Its complex eyes allow it to see extra colors—a fitting ability for a creature that’s high up on the list of the most colorful sea animals.
Nudibranchs (Nudibranchia)
Also known as sea slugs, nudibranchs are a group of vibrantly colored and patterned shell-less gastropods—2,000 species in all—that live primarily on ocean bottoms in tropical regions of the world. Weighing as much as 3.3 pounds (although many are much smaller), they use their antenna-like rhinophores (a sensory organ equivalent to a nose) to identify their prey: anemones, barnacles and other nudibranchs. Their color comes from the animals they eat, and some of them even retain their prey’s poison to use on would-be predators.
Spotted yellow boxfish (Ostracion cubicus)
Yes, it is decidedly, impossibly yellow. And yes, it is shaped like a box! It’s also speckled all over with brownish or blackish spots, and it plies the waters of the Indo-Pacific near coral reefs, munching on mollusks, crustaceans and worms. Its brilliant color isn’t just for beauty; it’s a warning to predators that it’s poisonous if eaten.
Discus (Symphysodon)
These fish—which are found in green, blue and reddish-brown—are actually river fish rather than ocean fish, inhabiting the Amazon basin and its river systems. These colorful sea creatures take shelter among submerged tree roots and trunks, and they get extra camouflage from their nine vertical stripes. They’re social enough to form mating pairs, but they are known to be aggressive when threatened.
Sea anemone (Actiniaria)
Sure, they’re beautiful and aesthetically pleasing. But this group of marine carnivores living near and on coral reefs spends their time waiting for prey to pass by to tangle them up in their poison-filled tentacles, according to National Geographic. Terrifyingly, some of them can grow out to 6 feet wide. Many of them have symbiotic relationships with algae, protecting them in exchange for a snack of oxygen and sugar that the algae make via photosynthesis.
Blue tang (Paracanthurus hepatus)
Blue tangs, made famous by Dory in the animated film Finding Nemo, are critical cleaners of tropical coral reefs, eating algae that might otherwise prove suffocating. This fish’s color changes at night, usually to a shade of white or lavender. And while Dory seems sweet in the movies, in real life, that’s far from the truth. Blue tangs are poisonous to eat and prickly to the touch, thanks to their razor-sharp spines.
Flower hat jelly (Olindias formosus)
It’s as puffy and pretty as a pom-pom, but the flower hat jelly, a native of the northwest Pacific Ocean around Japan and South Korea, delivers a nasty sting with its numerous tentacles—powerful enough to kill its prey of fish and invertebrates. It’s got “no head, heart, brain, bones, cartilage or real eyes, yet they’re among the major predators in the ocean,” according to the Monterey Bay Aquarium.
Large polyp coral (Blastomussa)
Seen here in a super-up-close macro photograph, this coral that’s native to Australia and nearby regions grows in bright, beautiful tubular clusters. It feeds at night, stretching its tentacles out from its hardened skeleton to catch any zooplankton that floats by. Although the world’s coral reefs are suffering the effects of climate change, they still provide critical habitat for many marine species.
Mandarinfish (Synchiropus splendidus)
Intensely colored and patterned, with an unusual assortment of wavy lines, these shy, small fish can live up to 15 years in the wild. They’re not only some of the most colorful sea animals around, they’re also bottom-feeders, snacking on small crustaceans and worms that live with them in their native region of the Pacific, around the Philippines, Indonesia and New Guinea. They have no scales, but they have a whopping 12 spines and can spawn weekly all year round.
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Sources:
- Fishbase: “Liopropoma carmabi“
- University of Washington: “What’s a Tunicate?”
- PangoVet: “9 Amazing Facts About Angelfish: Species, Lifespan & More”
- Oceana: “Peacock Mantis Shrimp”
- Australian Museum: “Yellow Boxfish, Ostracion cubicus Linnaeus, 1758″
- A-Z Animals: “Discus”
- Live Aquaria: “LiveAquaria CCGC Aquacultured Purple Australian Big Polyp Blastomussa Coral”
- Mental Floss: “Understanding Dory: 5 Facts About the Pacific Blue Tang”
- Monterey Bay Aquarium: “Flower hat jelly”
- Animal Diversity Web: “Synchiropus splendidus, Mandarin-fish”
- National Geographic: “Triggerfish”
- National Geographic: “Nudibranchs”
- National Geographic: “Sea Anemones”
