Swima bombiviridis

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Swima bombiviridis
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Annelida
Clade: Pleistoannelida
Clade: Sedentaria
Order: Terebellida
Family: Acrocirridae
Genus: Swima
Species:
S. bombiviridis
Binomial name
Swima bombiviridis
Osborn, Haddock, Pleijel, Madin & Rouse, 2009 [1]

Swima bombiviridis is a worm species that lives in the deep ocean. [2] It is also known as the green bomber worm or bombardier worm. This deep ocean pelagic (free-swimming) annelid has modified bioluminescent gills that can be cast off from an individual. These discarded gills somewhat resemble green "bombs" that remain illuminated for several seconds after they have been discarded. It is thought that this is a defensive mechanism rather than reproductive, as it is seen in both mature and juvenile individuals. [3] This species was the first of its genus, Swima , to be discovered, and was the only one with a formal scientific name as of 2010. [4] The genus name, Swima, is derived from the Latin, referring to the animal's ability to swim. The species name, bombiviridis, is derived from the Latin prefix bombus, meaning humming or buzzing (from which the English word bomb is derived), and the suffix viridis, which is Latin for the color green. Swima bombiviridis therefore translates to "swimming green bomber". [3]

Contents

Description

S. bombiviridis belongs to a clade that is morphologically distinct from other swimming acrocirrids by their transparent bodies, and single medial subulate branchiae. [5] The acrocirridae are closely related to the flabelligeridae, a sister groups of worms [6] [7] While species of Swima live in the ocean sediment, others remain suspended up to 444 meters above the sea floor. [8] S. Bombiviridis is further characterized by a gelatinous sheath and elliptical branchiae that it uses to drop 1mm long bioluminescent ‘bombs’ that luminesce for several seconds. [5] [8] They can grow over 30mm in length and 5 mm in width, making them relatively large in comparison to other worms of the acrocirrid family. They are also distinguished from other members of the acrocirridae, which consist of 8 genera of tiny, benthic worms that are immobile. [5]

Distribution and habitat

S. bombiviridis resides at depths up to 3600 meters and was first recorded off the coast of Monterey Bay, California. [9] Since then, they have only been found between 1–450 meters above the sea floor. [8] They are holopelagic, which means they remain pelagic throughout their entire life cycle, existing exclusively in the water column. [5]

The worms are not uncommon; they travel in groups by the hundreds, however, the remoteness of their habitat renders them incredibly challenging to investigate. Greg Rouse notes that each of the seven species in its clade exhibits various intricate head appendages. These appendages contain “bombs”, spheres that burst into light when released. The bombs evolved from gills, since they are in the same location as the gills, which can fall off easily. It remains unclear why this adaptation may have occurred. The implications of this evolutionary benefit may provide insight about how the environment of the S. bombiviridis, shapes the nature of its anatomical features. [9]

Morphology

S. bombiviridis are mobile deep sea acrocirrid worms that have 30 bristles made of chitin, or chaetae on each parapodium. They use these bristles to propel through the water by lateral undulation in combination with a power stroke and a recovery stroke. [8] [9]

S. bombiviridis only releases a few bioluminescent bombs at once upon mechanical stimulation along its length. Microscopy of the ‘bombs’ reveals that they contain hemolymph filled sacs separated by central chambers. These most likely evolved from homologous branchiae. [8] Although it has not been confirmed, S. bombiviridis employs this ability as a mechanism of distraction, parallel to squid that release bioluminescent liquid to escape their predators. [10] This is to be expected based on the many polychaetes that use bioluminescence for evasion. Furthermore, the bombs are unlikely to be used for reproduction due to the nature of this release, and due to the fact that these appendages are observed in both juvenile and adult forms. [8]

Discovery

Sbombiviridis was first discovered in 2009 by scientists at the Scripps Institution of Oceanography at UC San Diego, [9] and was initially reported in Science along with seven other new species of worm, forming a new clade of marine worms within Acrocirridae. [7]

Related Research Articles

<span class="mw-page-title-main">Clitellata</span> Class of annelid worms

The Clitellata are a class of annelid worms, characterized by having a clitellum – the 'collar' that forms a reproductive cocoon during part of their life cycles. The clitellates comprise around 8,000 species. Unlike the class of Polychaeta, they do not have parapodia and their heads are less developed.

<span class="mw-page-title-main">Trochoidea (superfamily)</span> Superfamily of sea snails

Trochoidea is a superfamily of small to very large vetigastropod sea snails with gills and an operculum. Species within this superfamily have nacre as the inner shell layer. The families within this superfamily include the Trochidae, the top snails. This superfamily is the largest vetigastropodan superfamily, containing more than 2,000 species.

<span class="mw-page-title-main">Terebellida</span> Order of annelid worms

Terebellida make up an order of the Polychaeta class, commonly referred to as "bristle worms". Together with the Sabellida, the Spionida and some enigmatic families of unclear taxonomic relationship, they make up the subclass Canalipalpata, one of the three main clades of polychaetes. Like most polychaetes, almost all members of the Terebellida are marine organisms. Most are small, sessile detritivores which live in small tubes they build from mud or similar substrate, or burrow in the sand. Their central nervous system displays characteristic apomorphies.

<i>Hesionidae</i> Family of annelids

Hesionidae are a family of phyllodocid "Bristle worms". They are marine organisms. Most are found on the continental shelf; Hesiocaeca methanicola is found on methane ice, where it feeds on bacterial biofilms.

Swima is a genus of marine polychaete worms found in the ocean at depths between 1,800 and 3,700 meters. Even if they are agile swimmers, they are often seen hanging immobile in the water column as they are neutrally buoyant. This deep ocean pelagic (free-swimming) genus has modified bioluminescent gills that can be cast off from an individual. These discarded gills somewhat resemble green "bombs" that remain illuminated for several seconds after they have been discarded. It is thought that this is a defensive mechanism rather than reproductive, as it is seen in both mature and juvenile individuals. And because they are eyeless, communicating with light would be difficult. Swima worms are closely related to the recently discovered genus Teuthidodrilus, another pelagic cirratuliform of the bathyal zone.

Teuthidodrilus samae, dubbed as the squidworm, is a species of acrocirrid marine annelid worms. It is free-swimming and can be found in the deep sea water column at depths of 2,039 to 2,912 m. It feeds on marine snow and can grow to about 9 cm (3.5 in) in length and 1 cm (0.39 in) in width. It is named for the ten squid-like appendages emerging from its head. It was discovered in 2007 in the benthopelagic zone of the Celebes Sea, near the Tawi-Tawi islands of the Philippines. It is the only species in the genus Teuthidodrilus.

<i>Acrocirridae</i> Family of annelids

Acrocirridae is a family of polychaete worms. Acrocirrids are detritivores, catching falling particles with numerous long prostomial tentacles. There are eight known genera, and at least 21 described species and subspecies within the Acrocirridae. The acrocirrids are primarily benthic (seabed-dwelling) animals, but at least two genera appear to have evolved or adapted to a pelagic (free-swimming) habitat.

<span class="mw-page-title-main">Opabiniidae</span> Extinct family of basal arthropods

Opabiniidae is an extinct family of marine stem-arthropods. Its type and best-known genus is Opabinia. It also contains Utaurora, and Mieridduryn. Opabiniids closely resemble radiodonts, but their frontal appendages were basally fused into a proboscis. Opabiniids also distinguishable from radiodonts by setal blades covering at least part of the body flaps and serrated caudal rami.

Vema is a genus of deep-sea molluscs, monoplacophorans. The genus is named after the oceanographic Research Vessel Vema.

Kirk J. Fitzhugh is the curator at the Natural History Museum of Los Angeles County, a position he has held since 1990. His research focuses on the systematics of polychaetes and on the philosophical foundations of evolutionary theory. Fitzhugh is a critic of DNA barcoding methods as a technical substitute for systematics. He attends Willi Hennig Society meetings where he has argued that "synapomorphy as evidence does not meet the scientific standard of independence...a particularly serious challenge to phylogenetic systematics, because it denies that the most severely tested and least disconfirmed cladogram can also maximize explanatory power." His graduate supervisor was V. A. Funk, from the U.S. National Herbarium, National Museum of Natural History, Smithsonian Institution MRC. He completed his doctoral thesis on Systematics and phylogeny of Sabellid polychaetes in 1988 while he was a research scientist at the LA County museum He married a lawyer named Nancy E. Gold in 1989.

Heronidrilus gravidus is a species of oligochaete worm, first found in Belize, on the Caribbean side of Central America.

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<span class="mw-page-title-main">Karen Osborn</span> American annelidologist

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<i>Phyllodoce lineata</i> Species of annelid worm

Phyllodoce lineata is a species of polychaete worm in the family Phyllodocidae. It is native to the northeastern Atlantic Ocean and the Mediterranean Sea where it occurs in the intertidal and shallow sub-tidal zones on soft sediment.

<span class="mw-page-title-main">Tomopteridae</span> Family of annelids

Tomopteridae is a family of holopelagic polychaetes belonging to the order Phyllodocida. The genus Tomopteris consist of about 70 species, and the three other genera of one known species each. Length varies from just 1-2 cm to 30 cm. These are very active swimmers, and have some of the highest metabolic rate among annelids. To increase buoyancy they have a large body cavity (coelom) filled with body fluid of a density similar to seawater. With the coelom taking up much of the inner space, the muscular system has been reduced to a mesh just below the epidermis. The circulatory system has been lost, and the coelomic fluid has taken over the role of transporting oxygen, nutrients and gametes. Instead of a heart the inner surface of the worm is covered with cilia that moves the fluid around inside the body. The absence of septa between the segments makes the circulation more efficient. A series of extretory organs called metanephridia consists of ciliated funnels which opens to the coleomic cavity and connects with the exterior though a nephridiopore. Some species are bioluminescent, and produce a yellow light.

Frenulata, "beard worms", is a clade of Siboglinidae, "tube worms". They are one of four lineages with numerous species. They may be the most basal clade in the family. Despite being the first tube worms to be encountered and described, they remain the least studied group. This is because of their slender shape, they often get destroyed as a result of being caught as bycatch or poor preservation. They are found primarily in deep, muddy sediments, cold seeps, and anoxic firth sediments.

<i>Notophyllum foliosum</i> Species of annelid

Notophyllum foliosum is a species of annelid in the family Phyllodocidae. Roughly 12 millimeters long, the annelid is bristly and covered in scale-like cirri. The species is found in shallow areas of the seafloor of the Mediterranean, Scandinavia, and Madeira. It was originally described as Phyllodoce foliosa in 1835 and was moved to the genus Notophyllum in 1923. The species was split in two in 2010, with the deeper-dwelling Notophyllum crypticum being designated its own species.

References

  1. ↑ Osborn KJ, Haddock SHD, Pleijel F, Madin LP, Rouse GW (2009). "Deep-sea, swimming worms with luminescent "bombs"". Science . 325 (5943): 964. doi:10.1126/science.1172488. PMID   19696343.
  2. ↑ Moskowitz, Clara (20 August 2009). "Sea Creature Releases Glowing Decoy 'Bombs'". LiveScience. Retrieved 2009-11-14.
  3. 1 2 International Institute for Species Exploration (2010). "Bombardier Worm". Top 10 New Species – 2010. Tempe, Arizona: Arizona State University. Archived from the original on 2010-12-28.
  4. ↑ Osborn KJ, Rouse GW (2010). "Phylogenetics of Acrocirridae and Flabelligeridae" (PDF). Zoologica Scripta . 40 (2): 204–219. doi:10.1111/j.1463-6409.2010.00460.x.
  5. 1 2 3 4 Rouse, Greg W.; Haddock, Steven H. D.; Osborn, Karen J. (2011-11-01). "Swima (Annelida, Acrocirridae), holopelagic worms from the deep Pacific". Zoological Journal of the Linnean Society. 163 (3): 663–678. doi: 10.1111/j.1096-3642.2011.00727.x . ISSN   0024-4082.
  6. ↑ Rouse, G. W.; Fauchald, K. (1997). "Cladistics and polychaetes". Zoologica Scripta. 26 (2): 139–204. doi:10.1111/j.1463-6409.1997.tb00412.x. ISSN   1463-6409.
  7. 1 2 Osborn, Karen J.; Rouse, Greg W. (2010). "Phylogenetics of Acrocirridae and Flabelligeridae (Cirratuliformia, Annelida)" (PDF). Zoologica Scripta. 40 (2): 204–219. doi:10.1111/j.1463-6409.2010.00460.x. ISSN   1463-6409.
  8. 1 2 3 4 5 6 Rouse, Greg W.; Madin, Laurence P.; Pleijel, Fredrik; Haddock, Steven H. D.; Osborn, Karen J. (2009-08-21). "Deep-Sea, Swimming Worms with Luminescent "Bombs"". Science. 325 (5943): 964. doi:10.1126/science.1172488. ISSN   0036-8075. PMID   19696343.
  9. 1 2 3 4 "Scientists Discover Bioluminescent 'Green Bombers' from the Deep Sea". Scripps Institution of Oceanography. 2012-10-31. Retrieved 2019-04-02.
  10. ↑ Cohen, Julia (April 10, 2016). "Shedding a Light on Bioluminescence". Dawson Environmental Science.
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