Odd Ocean Critters to Inspire Your Next Halloween Costume

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October 2023

It’s spooky season, and if you’re an ocean-lover looking for unique DIY Halloween costume ideas, we have some inspiration from across your National Marine Sanctuary System. Learn a few fun facts about strange and interesting animals found in the ocean, along with ideas on how to make a one-of-a-kind costume utilizing common craft supplies, such as paint, ribbons, and construction paper, and items found around the house, like cardboard, an old sheet, or a milk jug. These costumes can be made for anyone from babies to adults. Take the ideas below, get creative, and make it your own! While you’re out trick-or-treating in your homemade Halloween costume, don’t forget to share the fun ocean animal facts you learned in this guide.

Gulper Eel (Eurypharynx pelecanoides)

The gulper eel, also known as a pelican eel, is a deep-sea-dwelling eel found at depths of 1,600 to almost 10,000 feet in tropical and temperate regions. In 2018, the E/V Nautilus had a rare opportunity to film a gulper eel within Papahānaumokuākea Marine National Monument, showcasing their unique abilities. These odd eels have a pouch-like throat and stomach that they can quickly inflate in order to scoop up larger prey, such as a big squid, a school of fish, or a swarm of shrimp. This behavior reminds many people of a pelican expanding its throat pouch to scoop up fish, which is where the nickname comes from.

While their mouths are an impressive adaptation, they’re actually not the best of hunters because they have very small eyes, making it tough for them to locate prey in the deep, dark, depths that they live in. They have a very thin whip-like tail and lack pelvic fins, which help fish with balance, and do not have a swim bladder, which help fish maintain buoyancy. For these reasons, they are not the best of swimmers.

Portuguese Man O’ War (Physalia physalis)

Portuguese man o’ war may look like a type of jelly, but they are actually a type of siphonophore, which are closely related to corals and jellies. These colonial animals are made up of groups of specialized organisms, known as zooids, that work together as a unit. Each of the four specialized zooids of a man o’ war is responsible for a specific task, such as floating (the pneumatophore), capturing prey (the dactylozooids, or tentacles), feeding (gastrozooids), and reproduction (gonozooids).

These ocean drifters generally live in warm tropical and subtropical waters and get carried by wind and currents into the waters such as Florida Keys National Marine Sanctuary, Gray’s Reef National Marine Sanctuary, and Flower Garden Banks National Marine Sanctuary, and can appear in groups of more than 1,000. The top part of their body is a float, or a sail, referred to as a “pneumatophore,” that is partially filled with carbon monoxide. Like other animals in the Phylum cnidaria, Portuguese man o’ war have stinging organelles, called nematocysts, that line their long dactylozooids and are meant to stun and capture their prey. These long tentacle and polyp colonies that extend below the ocean’s surface from the float can reach lengths of up to 30 feet!

Black Seadevil Anglerfish (Melanocetus spp.)

The deep sea is a dark place, and food can be hard to find without a good strategy. An anglerfish is a type of bony fish that lives in the deep sea, that uses fishing rod-like projection with a light at the end to lure in its prey. The light is produced by millions of bacteria inside of a specialized organ (the “esca”) through a chemical process called bioluminescence. There are over 200 species of anglerfish, but the most widely known and recognizable is the black seadevil anglerfish, which has long, spiky teeth protruding from its jaws.

The black seadevil anglerfish, like the one in this video from Monterey Bay National Marine Sanctuary, uses its bioluminescent lure to attract prey. When the timing is right and an unsuspecting prey swims too close, the anglerfish snatches it up. This sneak attack style of feeding is known as “ambush predation.”

Decorator Crab (Superfamily Majoidea)

Decorator crabs are one of nature’s masters of disguise. There are several different species of decorator crab, all belonging to the superfamily Majoidea. These creative crabs use materials from their environment to hide from, or ward off, predators. They do this by covering their hard outer shell (exoskeleton) and legs with algae and animals such as sponges, anemones, tunicates, and bryozoans in order to blend in with the seafloor environment.

Their bodies are covered in fine bristly hairs that act like a type of Velcro, latching onto the chosen decorations. Some decorator crabs are highly selective about the decorations they choose, such as the furcate spider crab (Stenocionops furcatus), which often chooses to wear the hitchhiker anemone (Calliactis tricolor) on parts of its body to deter predators. In this symbiotic relationship, the crab gets protection, and the anemone gets a place to live and discarded scraps of the crab's food. This particular relationship has been observed throughout the tropical Atlantic and Gulf of Mexico, and was first documented in Flower Garden Banks National Marine Sanctuary in 2007 during a Stetson Bank Long Term Monitoring Cruise.

Crabs are crustaceans that have 10 legs. Most decorator crabs are a type of spider crab, which tend to have long, thin limbs and a triangular carapace (shell). They have a front pair of legs with pincers, and the remaining four pairs of legs are pointy at the end. Like many other crustaceans, rather than the shell growing along with the body of the decorator crab, the crab has to shed its shell in a process known as “molting.” Each time the decorator crab molts, it carefully removes its anemones, sponges, and other decorations so it can use them on its newly grown exoskeleton.

Can you find the decorator crab hiding on the reef in this 360 video of Cordell Bank National Marine Sanctuary?

Dumbo Octopus (Grimpoteuthis spp.)

It’s not a flying elephant that lives in the sea; the dumbo octopus is a type of umbrella octopus that is found deeper in the ocean than any other type of octopus (over 13,000 feet). Umbrella octopuses swim by flapping a pair of very large fins that protrude from the mantle above the eyes. There are 14 known species of umbrella octopus, all belonging to the Grimpoteuthis genus. These eight-armed inhabitants of the deep-sea feed on snails, worms, bivalves, isopods, and other small prey.

Unlike many of the other octopuses found at shallower depths, dumbo octopuses lack chromatophores and are unable to color-change to camouflage with their surroundings. Their bodies are usually pale or unpigmented, with some dark purple pigmentation on the oral surface of the arms (the side that has the suckers on it).

Dumbo octopuses are a rare sighting and a special treat for researchers exploring the ocean, Recently, Ocean Exploration Trust’s E/V Nautilus spotted a dumbo octopus in Papahānaumokuākea Marine National Monument at over 5,250 feet (1,600 meters) deep while exploring Woollard Seamount, roughly 40 nautical miles north of Hōlanikū (Kure Atoll).

Fun fact: Octopuses do not have tentacles! They have eight appendages, each of which has rows of suckers running its length. But these are not “tentacles” like you would see on a squid. In strict anatomical terms, they are referred to as “arms.”

Other Possibilities

There are lots of other bizarre-looking, funky, and spooky animals found throughout your national marine sanctuaries and beyond. If the examples above didn’t get you into the Halloween spirit, see if any of the other options below can inspire your next ocean-themed costume idea!

• Lionfish
• Mantis shrimp
• Nudibranch
• Barreleye fish
• Sea hare
• Sea cucumber

 

Rachel Plunkett is the writer/editor for NOAA’s Office of National Marine Sanctuaries