9 Bizarre Sea Creatures: From the Shallows to the Dark Depths

 9 Bizarre Sea Creatures: From the Shallows to the Dark Depths

Image Credit: YouTube

Not all sea creatures are blessed with good looks. In fact, odd-looking sea creatures, like the flabby blobfish and spooky frilled shark, make up the vast majority of marine fauna. Since their appearance doesn’t conform to our notion of beauty, these animals don’t get the same amount of attention and conservation funding as whales, reef sharks, and orcas do.

But while strange animals like the frogfish, blue dragon fish, and gob-faced squid look like evolution skipped them, on the inside, it’s quite the opposite. Their biological makeup and genetic predisposition are beyond fascinating. Allow us to introduce you to nine of the most bizarre sea creatures lurking in the world’s oceans, from the shallows to the deep abyss.

Bobbit Worm

bobbit worm or sand striker poking out of ocean floor

First on the list is the bobbit worm, arguably one of the most terrifying and bizarre sea creatures living within the seabed.

Eunice aphroditois, or the bobbit worm, is a predatory polychaete worm that lives on the ocean floor at depths of 10 to 40 meters in the Indo-Pacific. The Bobbit worm is omnivorous, but it has some special features that make it a particularly skilled and ruthless hunter. Growing up to three meters in length, this clever worm buries itself in the substrate, which could be gravel, coral, sand, or even mud, leaving only its five antennae protruding from the sea floor.

When these antennae are stimulated by passing prey, the bobbit worm bites with its razor sharp teeth, pulling its victim into the substrate to be consumed. This bite can be delivered with such speed, slicing the prey in half! But it’s not just the bobbit worm’s bite you should fear; it’s also covered in stinging bristles that can result in permanent numbness in the area of human flesh that touches it. Check out what happens when an equally fearsome lionfish stumbles unwittingly across the lair of a Bobbit worm.

Living Rock

living rock or piure, a delicacy in Peru & Chile

Photo by sergio.majluf / CC BY 2.0

Contrary to its name, living rock is actually a tunicate, a type of marine invertebrate sometimes called a sea squirt or piure in Chile and Peru. Other marine invertebrates, like coral, also have soft living parts inside a hard shell, but living rock takes it to an entirely new level.

Living rock or Pyura chilensis does not move—ever. Instead, it survives by taking in water and extracting microorganisms for food while remaining in the same place throughout its lifetime, making it appear like another rock on the seabed. When cut open, however, it reveals a vibrant red, semi-solid flesh with clear fluid—its blood. Some locals prize the meat as a delicacy, but consider it as somewhat of an acquired taste.

One of the most interesting facts about these strange sea creatures is how they reproduce. The piure begins life as a male, but as it grows and approaches reproduction age, it becomes hermaphroditic, meaning that it has both male and female traits. When it’s fully mature, it will send both eggs and sperm into the water, relying on ocean currents and chance to fertilize the eggs. This species is found in clusters, but even a single organism has the ability to reproduce without help from its friends.

Sea Angel

sea angel swimming in the midnight zone

Nearly every diver has seen the James Cameron blockbuster The Abyss. And who could forget those weird sea creatures that end up saving everyone’s butt several times in the movie? While the creatures in that tale were intended to have a supernatural affectation, many keen minds have noted the similarities between those fictional beings and actual marine organisms, specifically salps, pyrosomes, and a little creature called the gymnosomata, or the sea angel.

Although its moniker suggests an otherworldly creature, the sea angel is nothing more than a pelagic gastropod mollusk, but without the protective shell the rest of its kind has. The feet of these free-swimming organisms have evolved into wing-like appendages that help them swim through the water column. They feed almost exclusively on sea butterflies, small pelagic swimming sea snails with similar wing-like appendages. While sea butterflies have a shell, this doesn’t stop the sea angel from consuming them using a series of hooks and a toothed radula. Due to its transparent body, the entire act of feeding is visible from beginning to end. Check out this fascinating footage of a sea angel in the wild.


3D illustration of a tardigrade or swimming water bear

The tardigrade or “water bear” may be a microscopic organism (no more than 2 mm in length) but it’s one of the most remarkable creatures on the planet. Our cute little water bear is capable of living in environments where other insects can’t. You’ll also find it in every corner of the Earth: from volcanic hot springs to the poles, from the top of the Himalayas to ocean depths of more than 14,000 feet.

Researchers have even launched tardigrades into orbit to see whether they could withstand the vacuum of space, not to mention the intense radiation, a journey from which they returned completely unscathed. Various tests show that tardigrades can withstand temperatures as low as -459F, and as high as 304F, while simultaneously taking on 1,000 times the radiation other animals can stand.

Not to be outdone by itself, the tardigrade can also go nearly a decade without water by going into a dormant state called cryptobiosis. Rehydration brings it back to life, a cycle which the tardigrade can repeat as often as necessary throughout its life, significantly expanding its life span. The tardigrade’s curious abilities have led some scientists to speculate on its true origin and explore the possibility that it’s a migrant from another planet.

Tardigrades are so abundant in our ecosystems that a bit of foraged dry moss, beach sand, seawater, soil, or freshwater sediment holds at least one, whether active or in cryptobiosis. So grab yourself a microscope, a petri dish, and some natural debris and try your luck at hunting the world’s most common “bear”!


Atlantic spiny lumpsucker underwater

Of all the strange ways sea creatures have evolved over the millennia to better adapt to their environment, one that never fails to elicit curiosity is the lumpsucker. With a name based purely on visual characteristics, the lumpsucker is a small, rotund fish that resembles a puffer fish. But the really interesting part of its anatomy is its pelvic fins, which have evolved into adhesive discs or “suckers.” These sucker fins allow the lumpsucker to stick securely to ocean substrates, where it can remain stationary while it seeks out prey.

Like the puffer fish, this bizarre little fish is not a strong swimmer, relying only on a tail fin and small pectoral fins for propulsion through the water column. To survive in the wild, it relies on its ability to adhere to surfaces for safe feeding and self-defense. The lumpsucker feeds on sessile invertebrates, including marine worms, mollusks, and small crustaceans. There are also some pelagic species that prey on jellies, which can be easily pursued and overtaken by this awkward fish. Because of their comedic appearance and relatively docile temperament, lumpsuckers are popular among aquarists. Check out a Pacific Spiny Lumpsucker holding it down inside a tank, capturing the bemusement of a tiny Crescent Gunnel.

Sarcastic Fringehead

sarcastic fringehead bizarre sea creature

The sarcastic fringehead hails from the blennioid suborder of the Chaenopsidae family, and is essentially like all other blennies in every way but one: that enormous mouth. It burrows into the substrate, holes up in coral or even the abandoned shells of a hermit crab, and is ruthlessly defensive of its territory.

The sarcastic fringehead poses no threat to humans except for its alarming appearance. But it is this look that wards off predators and other passersby from lingering too long in its burrow. Should another sarcastic fringehead take up residence too close, however, that’s when the show begins. Both fish will expand their formidable mouths and needle-like teeth, and if that doesn’t do the trick, then there’s nothing left to do but begin wrestling. Mouth wrestling. Until one of them skulks away, ashamed of its weak mouth.

This behavior makes them fierce father figures as well. The female sarcastic fringehead will lay her eggs in an abandoned shell or other fairly concealed opening, and then leaves dear old dad to it. She unfortunately will never be around to witness the birth of her own children because even she isn’t exempt from the “Get off my %@#& lawn!!”

You don’t even have to go somewhere exotic to find these weird sea animals; sarcastic fringeheads populate areas of the Pacific Ocean between three and 73 meters deep, from San Francisco, California, down to central Baja California in Mexico. If you happen to run into one on a dive, feel free to engage in a battle of wits, but just remember: sarcasm hurts everyone. In the meantime, watch this fantastic sarcastic fringehead fight for its right to dominate the seafloor.

Melibe Leonina

hooded nudibranch or melibe leonina bizarre sea slug

Here at Aquaviews, we are huge fans of nudibranchs for their amazing variety of shapes, colors, and sizes, not to mention the fact that they’re found in virtually every sea across the globe. Our favorite species is the Melibe leonina, more commonly known as the hooded nudibranch or the lion’s mane nudibranch, found primarily in colder waters and kelp forests off the western coast of North America.

This bizarre sea creature travels the same way other nudibranchs do, by propelling itself through the water with a side-to-side sort of gyration. It is a predatory species, feeding on minute creatures that proliferate the water column, including amphipods, copepods, small mollusks, larvae, ctenophores, and even jellyfish.

The jelly is the most interesting form of prey for the Melibe leonina. The sensory tentacles it uses to detect prey resembles the appearance of a jellyfish, making it an easy target. When a jelly finds its way inside the oral hood, it shuts close rapidly with the tentacles intertwined so it can bring the food into its mouth—like Venus flytraps of the sea. The entire body of this weird sea animal is translucent, with four to six pairs of paddle-like appendages that can be shed when threatened, distracting the attacker while it makes its escape.

One of the most curious features of the Melibe leonina is its odor (similar to that of fruit-flavored gum), which it emits when removed from the water or kept in captivity. For this reason, along with their flower-like appearance, a group of this species is called a bouquet. Check out these incredible videos of the Melibe leonina in action.

Dumbo Octopus

grimpoteuthis or dumbo octopus swimming in deep sea

Photo by NOAA / CC BY-SA 2.0

Cephalopods have long captured the human imagination, whether it be in bemused curiosity or morbid fear. Fear is certainly an understandable reaction, as squid and octopus have been stigmatized over centuries as fearsome and strange sea creatures of the deep—man-eaters capable of disappearing entire ships in the still of the night. Although they are predatory creatures, the typical diet of a cephalopod consists of crustaceans, shelled mollusks, and gastropods, prey that can be pierced with their sharp beak and torn to pieces—not the dense and awkward bone structures of humans. Indeed, cephalopods have much more reason to fear man than the other way around!

But one cephalopod that most certainly elicits “ooh’s” and “aww’s” rather than terrified panic is the Grimpoteuthis, or more adorably, the Dumbo octopus. Named for a pair of fins that protrude from either side of its head, the Dumbo octopus is a bathypelagic creature, residing in depths of 1,000 to 4,000 meters, with reports of sightings as deep as 7,000 meters. This region of the sea receives no natural light, resulting in clever adaptations of the creatures who live there.

Although the Grimpoteuthis is capable of propulsion through the use of its funnel, arms, and ear-like fins, it spends much of its time hovering over the seabed, searching for worms, amphipods, and crustaceans to swallow whole. Instead of the usual crushing and tearing methods that other cephalopods employ, this method of predation allows this unusual cephalopod to conserve energy—a valuable resource in these Cimmerian reaches of the ocean.


The Teuthidodrilus, or squidworm, is a recently discovered species of marine polychaete worm. In 2007, marine biologists discovered this interesting sea worm in the western part of the Celebes Sea, a deep oceanic basin in the depths of the Philippines that is part of the Coral Triangle. This marine worm has intrigued scientists everywhere due to its unique body structure and its very recent discovery.

The squidworm is measured to be nearly four inches long, quite sizable for a marine worm. It is named for its head that looks like it’s covered in squid-like tentacles. This worm has various appendages, some of which are even longer than its body. Eight arms are used for breathing, and two long, coiled appendages are used for feeding. Six pairs of sensory organs emerge from its head to provide the squidworm the ability to taste and smell, and propulsion paddles are present down the length of its body to allow upright swimming.

As a newly recognized species, not much is known yet about this type of marine worm, but scientists believe that its numerous appendages and odd body structure have a deeper meaning for this creature. Because of its strange body characteristics, the squidworm may be a transitional form of worm, evolving as it exists in two diverse habitats. The squidworm lives in a sort of in-between area of the ocean, making it subject to conditions that are not typically the first choice of marine worms. It does not exist near the light-filled surface of the water, nor does it inhabit the dark, rocky seafloor.

The worm uses its two coiled appendages on its head to feed on plankton in the ocean water. It does not seem to be a predator, as it has only been noted to eat plankton and sinking particles of microscopic plants and animals. Multiple sets of observations have reported a profusion of this worm in the Celebes Sea, suggesting that it is quite common. The new type of marine worm is a captivating example of the continued discoveries of new species and of the vast wonders that this world holds.

This artcile was copied verbatim from Leisure Pro

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