Divers discovered tiny sea creatures that resemble 'swimming panda bear skeletons'

Divers exploring coral outcrops near Kumejima Island in Japan thought they had found novelty props for an aquarium display. Instead, their cameras captured a tiny siphon‑pumping animal whose stark white stripes and dark eye‑like spots looked like a cartoon panda wearing a skeleton costume.

The inch‑tall surprise soon went viral in diver forums, and what began as a curiosity post led researchers to a bona fide species never cataloged before.

Study coauthor Naohiro Hasegawa of Hokkaido University arranged dives, collected specimens, and confirmed that the creature belonged to the genus Clavelina, yet was distinct enough for its own name.

New Clavelina species

Photos first appeared online in 2017, letting scientists inspect body shapes and color patterns without leaving their desks.

Independent images posted by different dive operators also revealed that the animals occurred at several reef patches between 16 and 66 feet, giving a hint that the oddity was not a photo trick.

Hasegawa’s team located colonies in 2022 and used gentle suction devices to move living clusters into chilled seawater dishes aboard their boat.

Laboratory microscopy then mapped the arrangement of internal vessels, showing transverse white bars that create the “bones” illusion and four discrete black pigment patches on each zooid.

Morphology and genetics

Thanks to the clear photos and field data, the scientists could write a precise morphological description even before genetic work began.

Their approach echoes a broader move toward passive citizen‑science, where researchers mine social media for reliable species observations instead of waiting for mailed specimens.

A final round of underwater surveys returned measurements on abundance and depth range, ensuring that the panda‑masked animal’s ecological niche was documented alongside its anatomy.

Those data are now archived with Japan’s National Museum of Nature and Science for easy access by future investigators.

Clavelina ossipandae

The new animal was christened Clavelina ossipandae, a nod to its bottle‑shaped body (Clavelina is Latin for “little bottle”) and its bone‑and‑panda palette.

Each transparent zooid grows no longer than 0.8 inches, or about 20 millimeters, and sits free of its neighbors rather than sharing a common tunic, one of seven features that separate it from 44 known congeners.

Live specimens show ten to fourteen double‑row gill stigmata and two muscular ribbons running from abdomen to endostyle, details that place the species within the tunicate lineage while ruling out close look‑alikes such as Clavina picta or Clavina moluccensis.

“The white parts that look like bones are the blood vessels that run horizontally through the sea squirts’ gills,” explained Hasegawa.

Another quirk involves the jet‑black endostyle, a mucus‑secreting groove used to trap food.

Comparable grooves in other Clavelina members are pale, so the noir throat offers an easy field mark for photographers trying to separate the skeleton panda from less flashy relatives.

Family ties and feeding

Sea squirts are sessile members of the phylum Chordata, meaning their swimming larvae carry a notochord similar to the backbone we humans develop. Adults, however, cement themselves to rocks and switch to a pump‑and‑filter lifestyle.

The skeleton panda follows the classic filter‑feeding routine, drawing seawater in through an oral siphon, passing it across a mesh of gill slits, and expelling it through an atrial siphon.

Every hour, a zooid the size of a thumbnail can process volumes of water many times its own body capacity, quietly removing bacteria and microalgae that would otherwise cloud the lagoon.

Because the colony sits in sunlit shallows, stray plankton is plentiful, and the animals rarely exceed snorkel depth. For coastal ecosystems, these compact filters act like living water purifiers, clarifying reef zones where corals and juvenile fish need light.

Clavelina genes seal the verdict

To double‑check that the panda mimic was not a color morph of an existing species, scientists sequenced 810 base pairs of the cytochrome c oxidase subunit I gene.

Two individuals differed by ten nucleotides, a 1.26 percent divergence, yet translated into identical amino acids, a pattern typical of intraspecific variation.

Phylogenetic analysis grouped the samples squarely inside the Clavelina clade, confirming that the combination of free zooids, panda mask, and gene signature warranted a fresh binomial.

Collection data were deposited in Japan’s National Museum of Nature and Science, making the record available for future comparative work.

Routine bar‑coding of new finds matters because many tunicates carry compounds of biomedical interest, including anti‑cancer metabolites.

Even if C. ossipandae never yields a drug, accurate placement in the tree of life guides bioprospectors toward branches more likely to host useful chemistry.

Bigger picture for these tiny creatures

Diver photos once rejected as casual snapshots turned out to be first drafts of a taxonomic paper, highlighting how amateurs can accelerate discovery when scientists stay alert to online chatter.

Mobile phone cameras now exceed the resolution of older lab instruments, so crisp images of soft‑bodied creatures travel the globe in seconds, creating virtual voucher collections.

Citizen monitoring platforms such as the Reef Environmental Education Foundation now log more than 300,000 underwater surveys gathered by 18,000 volunteer divers, a reminder that hobbyists routinely cover real estate scientists rarely see.

Their effort frees researchers to focus on analysis instead of boat time, accelerating species checklists worldwide.

The find also underscores how much biodiversity hides in plain sight. Kumejima is a popular snorkel destination, yet a palm‑sized colony remained unnamed until someone noticed its Halloween stripes.

Conservation planners use such surprises to argue for broad habitat protection, not just for charismatic megafauna but for sponge‑sized curiosities that stitch reef food webs together.

“We don’t really know why the pattern is there,” admitted Hasegawa. The skeleton panda invites questions about evolution of color in non‑visual animals. Pigment may discourage predators or shield tissues from ultraviolet light, or it may simply be metabolic spillover with no clear purpose. 

The study is published in Species Diversity.

—–

Like what you read? Subscribe to our newsletter for engaging articles, exclusive content, and the latest updates. 

Check us out on EarthSnap, a free app brought to you by Eric Ralls and Earth.com.

—–