''Diopatra claparedii'' is a species of tube-building

polychaete worm Polychaeta () is a paraphyletic class of generally marine annelid worms, commonly called bristle worms or polychaetes (). Each body segment has a pair of fleshy protrusions called parapodia that bear many bristles, called chaetae, which are ma ...

of the family

Onuphidae The Onuphidae are a family of polychaete worms. Characteristics Most onuphids have tubes. Some live semisubmerged in the substrate, but others carry their tubes around, and they can all rebuild their tubes if necessary. The tubes, thin and parch ...

. It is found dispersed along intertidal and subtidal benthic environments of South Asian waters, especially along the coasts of

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Singapore Singapore, officially the Republic of Singapore, is an island country and city-state in Southeast Asia. The country's territory comprises one main island, 63 satellite islands and islets, and one outlying islet. It is about one degree ...

Thailand Thailand, officially the Kingdom of Thailand and historically known as Siam (the official name until 1939), is a country in Southeast Asia on the Mainland Southeast Asia, Indochinese Peninsula. With a population of almost 66 million, it spa ...

, and the

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.Idris, I., & Arshad, A. (2013). Checklist of polychaetous annelids in Malaysia with redescription of two commercially exploited species. ''Asian Journal of Animal and Veterinary Advances, 8''(3), 409-436. This species is exploited by humans for

fishing bait Fishing bait is any bait (luring substance), luring substance used specifically to attract and fishing, catch fish, typically when angling with a fish hook, hook and fishing line, line. There are generally two types of baits used in angling: '' ...

, indication of

marine pollution Marine pollution occurs when substances used or spread by humans, such as industrial waste, industrial, agricultural pollution, agricultural, and municipal solid waste, residential waste; particle (ecology), particles; noise; excess carbon dioxi ...

, and as gold and silver

nanoparticle A nanoparticle or ultrafine particle is a particle of matter 1 to 100 nanometres (nm) in diameter. The term is sometimes used for larger particles, up to 500 nm, or fibers and tubes that are less than 100 nm in only two directions. At ...

biosynthesis Biosynthesis, i.e., chemical synthesis occurring in biological contexts, is a term most often referring to multi-step, enzyme-Catalysis, catalyzed processes where chemical substances absorbed as nutrients (or previously converted through biosynthe ...

agents.Pamungkas, J., Atang, A., & Wibowo, E. S. (2023). FIRST RECORD OF DIOPATRA CLAPAREDII GRUBE, 1878 (ONUPHIDAE, POLYCHAETA) FROM INDONESIAN WATERS, WITH SOME NOTES ON ITS ECONOMIC IMPORTANCE. ''Treubia, 50''(1), 11-20. Hussain, N. S., Harun, N. A., Radzi, M. N. F. M., Idris, I., & Ismail, W. I. W. (2018). Biosynthesis of silver nanoparticles from marine polychaete diopatra claparedii grube, 1878. ''Jurnal Teknologi, 80''(6), 181-187.Huai, P. C., Harun, N. A., Pei, A. U. E., Masimen, M. A. A., Ismail, W. I. W., & Idris, I. (2021). Biosynthesis of Gold Nanoparticles (AuNPs) by Diopatra claparedii Grube, 1878 (Polychaeta: Onuphidae) and Its Antibacterial Activity. ''Sains Malaysiana, 50''(5), 1309-1320.

Ecology

''Diopatra claparedii'' are tubicolous, meaning they reside in a tube for much of their life cycle.Berke, S. K. (2022). A review of Diopatra Ecology: Current knowledge, open questions, and future threats for an ecosystem engineering Polychaete. ''Biology, 11''(10), 1485. The tube is formed from sediment, rock, organic matter, and a

mucus Mucus (, ) is a slippery aqueous secretion produced by, and covering, mucous membranes. It is typically produced from cells found in mucous glands, although it may also originate from mixed glands, which contain both Serous fluid, serous and muc ...

that the worm excretes, and can range from 30-60 cm in length, found in burrowed into sediments of

littoral The littoral zone, also called litoral or nearshore, is the part of a sea, lake, or river that is close to the shore. In coastal ecology, the littoral zone includes the intertidal zone extending from the high water mark (which is rarely i ...

environments of

South Asian South Asia is the southern Subregion#Asia, subregion of Asia that is defined in both geographical and Ethnicity, ethnic-Culture, cultural terms. South Asia, with a population of 2.04 billion, contains a quarter (25%) of the world's populatio ...

coastal waters, with varying lengths visible above ground.Paxton, H. (2002). Diopatra Audouin and Milne Edwards (Polychaeta: Onuphidae) from Thailand. ''Phuket Marine Biological Center Special Publication, 24'', 101-114. Though other species of ''

Diopatra ''Diopatra'' is a genus of polychaete worms in the family Onuphidae. Description Members of this genus live in thick, parchment-like tubes that project from the sediment on the seabed. The tubes are covered on the outside by fragments of shell, ...

'' adorn their tubes with shells or protruding rocks, ''D. claparedii'' primarily utilizes mangrove leaves, larger pieces of which can be seen at the end protruding into the water column, and are sometimes used to 'cap' the tube.Brenchley, G. A. (1976). Predator detection and avoidance: ornamentation of tube-caps of Diopatra spp.(Polychaeta: Onuphidae). ''Marine Biology, 38'', 179-188.

Trochophore A trochophore () is a type of free-swimming planktonic marine larva with several bands of cilia. By moving their cilia rapidly, they make a water eddy to control their movement, and to bring their food closer in order to capture it more easily. ...

larvae of ''D. claparedii'' are pelagic and swim using

cilia The cilium (: cilia; ; in Medieval Latin and in anatomy, ''cilium'') is a short hair-like membrane protrusion from many types of eukaryotic cell. (Cilia are absent in bacteria and archaea.) The cilium has the shape of a slender threadlike proj ...

for just a few days before the larva begins to develop the characteristic chaetigers of adult polychaetes and begins building the tube.Arias, A., Woodin, S. A., & Paxton, H. (2023). An Introduction to Diopatra, the Amazing Ecosystem Engineering Polychaete. ''Biology, 12''(7), 1027. The adult worm does not leave the tube for the rest of its life cycle, except for brief extensions of the anterior end for feeding on nearby sediments and organisms, and exuding reproductive products. This makes the worm an important ecosystem engineer, along with the rest of the

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

''Diopatra'', because the tubes penetrate the sediment, help stabilize it and prevent

erosion Erosion is the action of surface processes (such as Surface runoff, water flow or wind) that removes soil, Rock (geology), rock, or dissolved material from one location on the Earth's crust#Crust, Earth's crust and then sediment transport, tran ...

, and create spaces between neighboring tube protrusions as well as cavities within the tubes themselves that allow small organisms to shelter or evade predation.Woodin, S. A. (1978). Refuges, disturbance, and community structure: a marine soft‐bottom example. ''Ecology, 59''(2), 274-284. ''Diopatra claparedii'' are omnivorous, and primarily feed on algal growths on or near the tube, nearby polychaetes, as well as various planktonic invertebrates. The tubes they reside in are thought to help with predator evasion, as movement near the worms causes them to retract rapidly into the tube.Nazri, M. U. I. A., Mahmud, M. H., Saidi, B., Isa, M. N. M., Ehsak, Z., Ross, O., ... & Ismail, W. I. W. (2021). Cellular and molecular profiles of anterior nervous system regeneration in Diopatra claparedii Grube, 1878 (Annelida, Polychaeta). ''Heliyon, 7''(2). Additionally, the worms use hydrostatically pressurized

parapodia In invertebrates, the term parapodium ( Gr. ''para'', beyond or beside + ''podia'', feet; : parapodia) refers to lateral outgrowths or protrusions from the body. Parapodia are predominantly found in annelids, where they are paired, unjointed late ...

and setae to pierce the sides of the tube, providing traction that limits extraction from the tube. Some setae along the body of the worm are specialized, and feature hooks that allow better attachment to the tube.

Reproduction

''Diopatra'' reproduce by broadcast spawning and subsequently, by random fertilization. Many adults of this genus are

protandrous Sequential hermaphroditism (called dichogamy in botany) is one of the two types of hermaphroditism, the other type being simultaneous hermaphroditism. It occurs when the organism's sex changes at some point in its life. A sequential hermaphrodit ...

sequential

hermaphrodites A hermaphrodite () is a sexually reproducing organism that produces both male and female gametes. Animal species in which individuals are either male or female are gonochoric, which is the opposite of hermaphroditic. The individuals of many ...

, likely due to the fitness benefits of first existing in a larger male form for competitive advantages in occupying space and prey capture. Though previously assumed to be

gonochoristic In biology, gonochorism is a sexual system where there are two sexes and each individual organism is either male or female. The term gonochorism is usually applied in animal species, the vast majority of which are gonochoric. Gonochorism contras ...

, since eggs or sperm (but not both) can be found on the body wall of sexually mature adults, there are now observations of at least 3 species' life cycles in ''Diopatra'' known to be protandrous sequential hermaphrodites, indicating it is likely more widespread within the genus, especially since previous accounts suggesting gonochorism do not observe the entire life cycle of the worm.Arias, A., Richter, A., Anadón, N., & Paxton, H. (2013). Evidence of simultaneous hermaphroditism in the brooding Diopatra marocensis (Annelida: Onuphidae) from northern Spain. ''Journal of the marine biological Association of the United Kingdom, 93''(6), 1533-1542.Arias, A., & Paxton, H. (2015). The cryptogenic bait worm Diopatra biscayensis Fauchald et al., 2012 (Annelida: Onuphidae)–Revisiting its history, biology and ecology. ''Estuarine, Coastal and Shelf Science, 163'', 22-36.Arias, A., Paxton, H., & Budaeva, N. (2016). Redescription and biology of Diopatra neapolitana (Annelida: Onuphidae), a protandric hermaphrodite with external spermaducal papillae. ''Estuarine, Coastal and Shelf Science, 174'', 1-17. Broadcast spawning is also a discrete, annual event, in which case adults exude gametes into the water column above the sediment bed where the tubeworms reside, though the

neurobiological Neuroscience is the scientific study of the nervous system (the brain, spinal cord, and peripheral nervous system), its functions, and its disorders. It is a multidisciplinary science that combines physiology, anatomy, molecular biology, ...

mechanism by which the animal recognizes the timing for spawning is not well understood.

Development

There have not been specific analyses of ''D. claparedii'' development, but studies of ''Diopatra'' more generally indicate that other members of the genus exhibit spiral cleavage, and develop indirectly from fertilized eggs to a ciliate trochophore larval form that is briefly pelagic, or, in some cases, occupies the tube formed by the parent.Allen, M. (1959). Embryological development of the polychaetous annelid, Diopatra cuprea (Bosc). ''The Biological Bulletin, 116''(3), 339–361. Uniquely, the development from zygote to ciliated larva only takes three hours in some cases, making it a very rapid process. From there, the trochophore metamorphoses into a metatrochophore, which exhibits chaetigers and parapodia as the adult does, though far fewer, and begins building the tube structure where it will develop into an adult with more numerous segments.

Physiology

''Diopatra claparedii'' is a dark, reddish brown polychaete, with many lateral

, as well as specialized sensory

appendages An appendage (or outgrowth) is an external body part or natural prolongation that protrudes from an organism's body such as an arm or a leg. Protrusions from single-celled bacteria and archaea are known as cell-surface appendages or surface app ...

such as tentacular cirri and antenna on the anterior end of the worm. In ''Diopatra'', the anterior end of the worms are cylindrical, while the posterior end exhibits dorsoventral flattening.Tong, T. L., & Chou, L. M. (1996). Diopatra bulohensis, a new species of Onuphidae (Polychaeta) from Sungei Buloh, Singapore. The main body consists of repeating segments called chaetigers, each with a pair of parapodia containing setae, the function of which varies depending on where on the body the chaetiger is located. The body of ''D. claparedii'' may have between 35 and 150 chaetigers, and those near the posterior and anterior ends have hook-like setae to assist with attachment to the tube. Setae in the middle of the worm tend to be serrate, rather than hooked, and have a number of different potential structural patterns, including bidentate, pseudocompound bidentate, and fulcate. The anterior end of the worm houses several key structures: palps, antennae, a prostomium with a mouth, peristomial cirri, and the characteristic spiraled

branchiae A gill () is a respiratory organ that many aquatic organisms use to extract dissolved oxygen from water and to excrete carbon dioxide. The gills of some species, such as hermit crabs, have adapted to allow respiration on land provided they are ...

that set the genus ''Diopatra'' apart from other sedentary polychaetes. Additionally, the

nervous system In biology, the nervous system is the complex system, highly complex part of an animal that coordinates its behavior, actions and sense, sensory information by transmitting action potential, signals to and from different parts of its body. Th ...

of ''D. claparedii'' is of special research interest, because it is able to undergo both anterior and posterior

regeneration Regeneration may refer to: Science and technology * Regeneration (biology), the ability to recreate lost or damaged cells, tissues, organs and limbs * Regeneration (ecology), the ability of ecosystems to regenerate biomass, using photosynthesis ...

. Regeneration is a common feature among annelids and, within them, polychaetes, but the ability to regrow from both ends of the body is not as widespread. This ability also helps them to survive predation, as when part of the body is pulled from the tube, the remaining segments may regrow the anterior end of the worm, though this process is subject to the degree of body fragmentation.

Evolution

''Diopatra claparedii'' belongs to the Phylum Annelida, Class Polychaeta, Order Eunicida, in the Family Onuphidae.Rouse, G.W. and Fauchald, K. (1997), Cladistics and polychaetes. ''Zoologica Scripta,26'': 139-204. Uniquely, the genus ''Diopatra'' is defined by a single characteristic that has not changed since the creation of the taxonomic group– the spirally-arranged branchial filaments around the trunk of the worm. However, within ''Diopatra'', there are not clear, distinctive features between species, and as such, identification has remained difficult and sometimes erroneous in literature across geographic regions.

Impacts on humans and technology

Interestingly, ''D. claparedii'' has potential for use in the sphere of

nanotechnology Nanotechnology is the manipulation of matter with at least one dimension sized from 1 to 100 nanometers (nm). At this scale, commonly known as the nanoscale, surface area and quantum mechanical effects become important in describing propertie ...

. Synthesis of silver and gold nanoparticles (AgNPs, AuNPs) often requires harsh and ecologically toxic reagents and chemicals. New directions aim to identify greener ways of synthesizing these important nanoparticles, including use of polychaete tissues as a reduction agent. Either physical or chemical reduction is used to create the silver or gold nanoparticles, and it has been found that frozen, pulverized ''D. claparedii'' tissue has reduction action that can successfully aid in the creation of the nanoparticles.

References

{{Morecats, date=November 2023 Errantia Animals described in 1878