''Chaetopterus pugaporcinus'', commonly known as the pigbutt worm or flying buttocks, is a species of worm first described by scientists at the

Monterey Bay Aquarium Research Institute The Monterey Bay Aquarium Research Institute (MBARI) is a private, non-profit oceanographic research center in Moss Landing, California. MBARI was founded in 1987 by David Packard, and is primarily funded by the David and Lucile Packard Foundation ...

in 2007. The worm is round in shape, approximately 10 to 20 millimeters in length (roughly the size of a

hazelnut The hazelnut is the fruit of the hazel tree and therefore includes any of the nuts deriving from species of the genus ''Corylus'', especially the nuts of the species ''Corylus avellana''. They are also known as cobnuts or filberts according t ...

), and bears a strong resemblance to a disembodied pair of buttocks. Because of this, it was given a Latin species name that roughly translates to "resembling a pig's rear." The worm has been observed residing just below the

oxygen minimum zone The oxygen minimum zone (OMZ), sometimes referred to as the shadow zone, is the zone in which oxygen saturation in seawater in the ocean is at its lowest. This zone occurs at depths of about , depending on local circumstances. OMZs are found worl ...

(OMZ) between 875 and 1,200 meters (2,800 to 4,000 feet) deep — even when the sea floor is significantly deeper. The worms are neutrally buoyant, and have been observed floating along with their mouth parts facing downward, and their hind parts towards the ocean surface. As these worms have shown no ability to swim or otherwise propel themselves through the water, and have no long, protruding appendages to catch prey with, they must rely on filter feeding to survive. Current theories suggest that they reside in the oxygen minimum zone because of its cornucopia of detritus and

marine snow In the deep ocean, marine snow (also known as "ocean dandruff") is a continuous shower of mostly organic detritus falling from the upper layers of the water column. It is a significant means of exporting energy from the light-rich photic zone to ...

, and that the worms produce clouds of mucous to capture particles of food and "

snow Snow comprises individual ice crystals that grow while suspended in the atmosphere—usually within clouds—and then fall, accumulating on the ground where they undergo further changes. It consists of frozen crystalline water throughout ...

," which they later draw into their mouths and ingest. ''C. pugaporcinus'' has been found to feed mainly on pelagic

phytoplankton Phytoplankton () are the autotrophic (self-feeding) components of the plankton community and a key part of ocean and freshwater ecosystems. The name comes from the Greek words (), meaning 'plant', and (), meaning 'wanderer' or 'drifter'. Ph ...

, as well as pelagic

foraminifera Foraminifera (; Latin for "hole bearers"; informally called "forams") are single-celled organisms, members of a phylum or class of amoeboid protists characterized by streaming granular Ectoplasm (cell biology), ectoplasm for catching food and ot ...

ns,

silicoflagellate Dictyochales (Silicoflagellates, or Dictyochophyceae ''sensu stricto'') are a small group of unicellular heterokont algae, found in marine environments. Characteristics In one stage of their life cycle, they produce a siliceous skeleton, compo ...

dinoflagellate The dinoflagellates (Greek δῖνος ''dinos'' "whirling" and Latin ''flagellum'' "whip, scourge") are a monophyletic group of single-celled eukaryotes constituting the phylum Dinoflagellata and are usually considered algae. Dinoflagellates are ...

s, and marine protists. The worm has a segmented body, but the middle segments are highly inflated, giving the animal a round shape. These

morphological characteristics Morphology, from the Greek and meaning "study of shape", may refer to: Disciplines * Morphology (archaeology), study of the shapes or forms of artifacts * Morphology (astronomy), study of the shape of astronomical objects such as nebulae, galaxies ...

are unique among chaetopterids. It is unknown whether the specimens found to date were adult or larval forms. As chaetopterid worms do not spend a predetermined amount of time as planktonic larva, it is possible that the specimens found were actually larva that had simply been unable to settle in an appropriate

benthic The benthic zone is the ecological region at the lowest level of a body of water such as an ocean, lake, or stream, including the sediment surface and some sub-surface layers. The name comes from ancient Greek, βένθος (bénthos), meaning "t ...

habitat for their species. Their unusual size (five to ten times larger than any known chaetopterid larvae) might indicate they were adults, but all currently known species of chaetopterid adults prefer to live in the benthic environment, and live in parchment-like tubes on the sea floor. Comparison to larval morphology has indicated that the specimens have a close relationship to either genus ''Chaetopterus'' or genus '' Mesochaetopterus'', and a

phylogenetic tree A phylogenetic tree (also phylogeny or evolutionary tree Felsenstein J. (2004). ''Inferring Phylogenies'' Sinauer Associates: Sunderland, MA.) is a branching diagram or a tree showing the evolutionary relationships among various biological spec ...

constructed from mitochondrial and ribosomal DNA sequences from twelve different

Chaetopteridae The Chaetopteridae are a family of marine filter-feeding polychaete worms that live in vertical or U-shaped tubes in tunnels buried in the sedimentary or hard substrate of marine environments. The worms are highly adapted to the hard tube they s ...

worms found them to be most closely related to other worms of the genus ''Chaetopterus''. In laboratory settings, ''C. pugaporcinus'' has been found to produce

bioluminescence Bioluminescence is the production and emission of light by living organisms. It is a form of chemiluminescence. Bioluminescence occurs widely in marine vertebrates and invertebrates, as well as in some fungi, microorganisms including some b ...

when physically stimulated. This bioluminescence is produced as a bright blue light that endures for 3 to 6 seconds. Additionally, the worm will produce very small bioluminescent green particles that are dispersed into its mucous cloud, and glow for 1 to 2 seconds before fading.

References

{{Taxonbar, from=Q7193261 Polychaetes Animals described in 2007