Beautiful Undersea Creepy Crawlies

On land, the idea of creepy crawlies — critters that creep, crawl, or both — tends to give folks the heebie jeebies. But those found in the ocean’s depths tend to be more visually interesting. Here are some to feast your eyes on.

Crinoid Shrimp

Crinoid shrimp live in a symbiotic relationship with their host, the crinoid. Crinoids are sea creatures found attached to a substrate when in their adult phase. They have feather-like arms that filter food from seawater. Symbiosis arises when the crinoid serves as a hiding place for the shrimp, while the shrimp helps clean up the crinoid. As two of these photos reveal, crinoid shrimp are carefully camouflaged against their host crinoid. But the shrimp are known to occasionally leave their host, particularly when shedding their older carapace. Notice the almost-transparent shedding above the crinoid shrimp in the far left photo.

Christmas Tree Worm

There’s a marine worm reminiscent of a Christmas tree, hence its common name of the Christmas tree worm. The worm has a tube-like body that is anchored to the coral substrate it has burrowed into. Radiating from its central spine are two crowns that look like Christmas trees. The crowns are in fact appendages that help catch phytoplankton for the worm to feed on. If the worm is startled, it retracts its crown-appendages back into its tube-like body, hidden within the coral substrate.

Sea Cucumbers

Sea cucumbers have long, cylindrical bodies. They look almost like underwater versions of caterpillars. Their mouth region has a ring of tentacles that can be retracted. Sea cucumbers are considered a delicacy in Asian and Pacific cultures, like that of the Japanese and the natives of Guam. Interestingly, there are reports that sea cucumbers have cancer-killing compounds, but more scientific research is needed for verification.


Crossaster — known sometimes as sunstars, rose stars, or even snowflake stars — look like starburst versions of the sun. They are a species of sea star and are thereby related to starfish. Crossaster, however, typically have more arms than the regular starfish. Nonetheless, crossaster share characteristics that all echinoderms have: radial symmetry and regeneration of body parts. Also, crossaster might not have eyes per se, but they do have light-sensitive organs called “eye spots.”

Sea Butterflies

Sea butterflies are sea snails that can swim. As members of the mollusk phylum and gastropod class, they have shells. Their shells are colorless, almost transparent. Sea butterflies are noted for having body adaptations that allow them to float and even swim freely in the ocean water. Wing-like lobes on a sea butterfly’s foot can be flapped for propulsion, as these photos illustrate.


Argonauts are octopi that live in chambered shells similar to those of the nautilus. They can alter their color as a camouflaging defense mechanism. Their shells, meanwhile, trap surface air and are used as buoyancy devices. Argonauts live close to the surface, which is unlike other octopi who prefer being closer to the seabed. The name ‘Argonaut’ etymologically refers to the Greek myth about the sailors who found the Golden Fleece.

Ribbon Eel

The ribbon eel is a type of moray eel. It is slender and elegant in color combination. Some have even likened its appearance to a Chinese dragon. In the wild they can live up to 20 years. But in captivity they rarely survive more than a month because they get easily stressed. It is thereby suggested that ribbon eels remain free in the wild, not to be captured nor sold off as pets nor as specimens.


Flounder are speckled flat fish that reside on the seafloor. They are known for having eyes that migrate. That is, up until their juvenile years, flounder eyes are located on either side of their brain. But, as they grow into adulthood, their eyes migrate onto the top surface of their body. Flounder are masters of disguise, capable of camouflaging themselves thanks to their mottling. Sadly, flounder are overfished for their tasty meat.


Nudibranchs are arguably the most beautiful of the marine creepy-crawlies. They are soft-bodied and in fact belong to the mollusc phylum as well as the gastropod class. They’ve merely shed their shells, which accounts for their etymological root nudus (Latin for naked). At times nudibranchs are called sea slugs, but that is inaccurate since there are sea slugs that belong to other taxonomic groups unrelated to the nudibranch. Nudibranchs have highly developed defense mechanisms. A nudibranch’s vibrant colors warn predators that it has toxins and stinging cells on its skin. Here are more pictures showcasing the gorgeous coloration and patterns of nudibranchs.

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