Serpula
Encyclopedia
Serpula is a genus
of sessile
, marine
annelid tube worms that belongs to the Serpulidae
family
. Serpulid worms are very similar to tube worms of the closely related sabellid
family, except that the former possess a cartilaginous
operculum
that occludes the entrance to their protective tube after the animal has withdrawn into it. The most distinctive feature of worms of the Serpula genus is their colorful fan-shaped "crown". The crown, used by these animals for respiration
and alimentation
, is the structure that is most commonly seen by scuba divers and other casual observers.
and taxonomic classification
of Serpula:
Higher taxonomic ranks
, Atlantic
, and Indian
oceans, Mediterranean Sea
, North Sea
, Red Sea
. Species of the Serpula genus are common on the west coast of North America from Alaska
to Baja California
, but are rarely if ever found on the east coast of the United States
. They are common in Europe
and Africa
.
Like most tube-building polychaetes, worms of the Serpula genus are benthic
, sedentary suspension feeders
. They secrete and inhabit a permanent calcareous
tube attached to hard substrata. As they do not travel outside their tubes, these worms do not have any specialized appendages for swimming.
Worms of the Serpula genus are commonly found attached to submerged rocks, shells, and even boats in many coastal areas around the world. They are found at depths ranging from intertidal
to at least 800 meters.
Predators include predatory starfish such as the Ochre Sea Star
(Pisaster ochraceous).
to form the head, at the anterior end of the body. Worms of the Serpula genus have two photoreceptors or "eyespots" on the peristomium. The prostomium bears a branchial "crown", a specialized mouth appendage which resembles a fan (for which the animals are given the name fanworms).
This crown, which can be extended for feeding and gas exchange, and rapidly retracted when threatened, consists of two bundles (one right and one left) of featherlike gill
s, known as branchiae or radiole
s. Each of these bundles consists of a single row of radioles attached to a branchial stalk and curved into a semicircle. These two semicircles form the funnel-shaped branchial crown. The mouth is at the apex of the funnel between the two branchial stalks.
When extended, these heavily ciliated
radioles trap particles of organic matter and transport it towards the mouth. While they are primarily feeding structures, the radioles also serve as respiratory organs. The radioles of different Serpula species are typically red, pink, or orange in color, with white transverse bands. Astaxanthin
, a carotenoid
pigment, is responsible for the bright red color of the crown of S. vermicularis. There are usually about 40 radioles in an adult.
One of these radioles, called an operculum, is a highly specialized structure located on the dorsal part of the head. The operculum consists of a long, thick stalk with a cartilaginous
, cone-shaped plug at the distal end. This plug can be used to seal the opening of the tube after the animal has retreated inside. The operculum, which is usually red in color, secretes a mucus which seems to possess antibiotic
properties. It is not unusual for the animal to have two opercula. Both serpulid and sabellid worms have radioles, but sabellids (such as Sabella pavonina
) lack an operculum.
A single median nephridiopore
is located dorsally on the head, between the upper lip and a median dorsal papilla. The anterior end of the fecal groove passes over it and urine is released from it into the waste current. Like all serpulids and sabellids, they have only a single pair of metanephridia, which empty via this nephridiopore.
(segments bearing chaetae). Chaeta
e are small appendages that aid the worm with mobility. The first of these segments is the collar segment (peristomium), to which the prostomium is attached. The peristomium bears an elaborate, delicate, membranous collar that overlaps the margins of the aperture of the tube and covers the opening of the tube when the head is extended.
There is a pair of calcium-secreting gland
s located near the midventral line on the posterior end of the peristomium. These glands open onto the "ventral shields", which are wide glandular pads on the ventral side of the anterior thoracic segments. The ventral shields secrete organic
material and use this, combined with the calcium secreted by the glands, to form a paste from which the tube is made.
These white calcareous
tubes are made of both calcite
and aragonite
. They are usually smooth with faint longitudinal ridges, curved but not strongly coiled, and are rarely more than 12 cm in length. The tube appears to be shaped by the ventral shields and by a collar which is just behind the head.
There is a median, longitudinal, ciliated, thoracic fecal groove on the dorsal midline of the thorax. It is a broad, shallow, relatively indistinct trough running the length of the thorax and ending at the head.
, on which the anus
is located. A fecal groove extends the length of the ventral midline of the abdomen. The fecal groove spirals across to the dorsal position as it reaches the thoracic region.
Vertical ciliary tracts in the grooves between adjacent abdominal segments move particles toward the abdominal fecal groove. Once in the abdominal fecal groove, further ciliary currents transport particulate matter (feces, gametes, etc.) from the depths of the tube, through the thoracic segment to the aperture where it can be released to the sea.
In the central circulatory system, the blood moves anteriorly from the tip of the abdomen to the front of the thorax through a sinus enveloping the alimentary canal, and posteriorly through a ventral blood vessel. The ventral vessel and the sinus communicate with each other by segmentally arranged ring vessels, and by a dorsal vessel, a transverse
vessel, and a pair of circumesophageal
vessels situated at the anterior end of the thorax. The dorsal vessel in some of the larger serpulids, like Serpula, possesses a valve and a muscular sphincter
, probably to prevent backflow of blood from the transverse vessel.
The blood circulation in the periphery, especially the radiole, is especially unusual. Instead of venous and arterial blood flowing through afferent
and efferent
vessels within the radiole, there is a single branchial sinus through which blood flows in both directions, in a tidal fashion. The vessels of the peripheral system receive their blood from the central system, returning it back along the same channels (i.e., these channels serve in both afferent and efferent directions).
The peripheral circulatory system has the following components: the two branchial vessels and their branches in the crown; the periesophageal vascular plexus
es; the vessels of the collar and lips; the vessels supplying the body wall, thoracic membrane, and parapodia. The single vessels in each radiole of the branchial crown, and the vessels of opercula, are all branches of the two branchial vessels.
When the crown is retracted inside the tube, the radioles and operculum cease to function as a respiratory organ. The movement of blood in the capillaries of the thoracic membrane and body wall continues, however. Under these circumstances, respiratory exchange is probably carried out between the blood in these vessels and the surrounding water, which is kept moving through the tube by vigorous pumping movements of the abdomen and also by the activity of the ciliary tracts.
muscles of the body wall of serpulids lack a special blood supply. The body surface in the larger serpulids, like Serpula, has a rich blood supply, and the water in contact with this surface is constantly renewed. It seems probable that the outer body surface of serpulids serves as a respiratory membrane
, supplying oxygen to the underlying muscles by diffusion
.
The biochemistry of the blood of Serpula is especially unusual in that the blood contains not only hemoglobin, but also chlorocruorin
. While all sabellids and serpulids employ chlorocruorin as an oxygen transport macromolecule, Serpula is the only genus that appears to possess both hemoglobin as well as chlorocruorin.
Chlorocruorin is an oxygen-binding hemeprotein whose affinity for oxygen is weaker than that of most hemoglobin
s. A dichromatic
compound, chlorocruorin is noted for appearing green in dilute solutions, though it appears light red when found in concentrated solutions. Its structure is very similar to erythrocruorin
, each molecule being composed of more than a hundred interlinked 16-17kDa
myoglobin-like subunits arranged in a giant complex with a total weight exceeding 3600kDa
. This enormous macromolecule
is free floating in the plasma, and not contained within red blood cells.
The ratio of plasma hemoglobin to chlorocruorin is high in younger individuals, but this ratio reverses as the animal matures. Presumably this reflects a lower oxygen consumption in the adult worm, relative to the juveniles.
along the length of this cord (including pleural, pedal and cerebral ganglia), and a series of small nerves in each body segment. Signals transmitted through the pedal ganglia allow the worms to retract rapidly into their tube if threatened.
stores and provides nutrients for gametes. When they reproduce, they simply shed their gametes straight into the water where the ova and spermatozoa become part of the zooplankton
and are carried by the currents to new sites, where the juvenile worms settle into the substrate. Length of the planktonic stage is unknown but comparison with other serpulids suggests it may be between six days and two months, although in other species the period has been shown to vary with season, salinity or food availability, and delayed settling may cause reduced discrimination of substrata during settling (see ten Hove, 1979 for additional references).
s, and possess a complete digestive system. Like other polychaetes, Serpula excrete with fully developed nephridia
.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of sessile
Sessility (limnology)
In limnology, sessility is that quality of an organism which rests unsupported directly on a base, either attached or unattached to a substrate. It is a characteristic of vegetation which is anchored to the benthic environment. There are two families of sessile rotifers: Flosculariidae and...
, marine
Marine (ocean)
Marine is an umbrella term. As an adjective it is usually applicable to things relating to the sea or ocean, such as marine biology, marine ecology and marine geology...
annelid tube worms that belongs to the Serpulidae
Serpulidae
Serpulidae is a family of sessile, tube-building annelid worms in the class Polychaeta. The members of this family differ from the sabellid tube worms in that they have a specialized operculum that blocks the entrance of their tubes when they withdraw into the tubes. In addition, serpulids secrete...
family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
. Serpulid worms are very similar to tube worms of the closely related sabellid
Sabellidae
Sabellidae are sedentary marine polychaete tube worms where the head is mostly concealed by feathery branchiae. They build tubes out of parchment, sand, and bits of shell...
family, except that the former possess a cartilaginous
Cartilage
Cartilage is a flexible connective tissue found in many areas in the bodies of humans and other animals, including the joints between bones, the rib cage, the ear, the nose, the elbow, the knee, the ankle, the bronchial tubes and the intervertebral discs...
operculum
Operculum (bryozoa)
In the bryozoan order Cheilostomata, the operculum is a calcareous or chitinous lid-like structure that protects the opening through which the polypide protrudes....
that occludes the entrance to their protective tube after the animal has withdrawn into it. The most distinctive feature of worms of the Serpula genus is their colorful fan-shaped "crown". The crown, used by these animals for respiration
Aquatic respiration
Aquatic respiration is the process whereby an aquatic animal obtains oxygen from water.-Fish:In most fish respiration takes place through gills. Lungfish, however, possess one or two lungs...
and alimentation
Filter feeder
Filter feeders are animals that feed by straining suspended matter and food particles from water, typically by passing the water over a specialized filtering structure. Some animals that use this method of feeding are clams, krill, sponges, baleen whales, and many fish and some sharks. Some birds,...
, is the structure that is most commonly seen by scuba divers and other casual observers.
Taxonomy
Following is a brief description of the cladisticsCladistics
Cladistics is a method of classifying species of organisms into groups called clades, which consist of an ancestor organism and all its descendants . For example, birds, dinosaurs, crocodiles, and all descendants of their most recent common ancestor form a clade...
and taxonomic classification
Taxonomic rank
In biological classification, rank is the level in a taxonomic hierarchy. Examples of taxonomic ranks are species, genus, family, and class. Each rank subsumes under it a number of less general categories...
of Serpula:
Higher taxonomic ranks
- The Serpula genusGenusIn biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
belongs to the SerpulidaeSerpulidaeSerpulidae is a family of sessile, tube-building annelid worms in the class Polychaeta. The members of this family differ from the sabellid tube worms in that they have a specialized operculum that blocks the entrance of their tubes when they withdraw into the tubes. In addition, serpulids secrete...
familyFamily (biology)In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
, also known as serpulid worms or tubeworms. - the Serpulidae family is one of 31 described families of the CanalipalpataCanalipalpataCanalipalpata, also known as bristle-footed annelids or fan-head worms, is an order of polychaete worms, with 31 families in it including the Sabellida and the Alvinellidae, a family of deep-sea worms associated with hydrothermal vents.The Canalipalpata have no teeth or jaws. Most are filter feeders...
orderOrder (biology)In scientific classification used in biology, the order is# a taxonomic rank used in the classification of organisms. Other well-known ranks are life, domain, kingdom, phylum, class, family, genus, and species, with order fitting in between class and family...
, also known as bristle-footed annelids or fan-head worms. In addition to the Serpulidae, the Canalipalpata also includes the fanworms (SabellidaeSabellidaeSabellidae are sedentary marine polychaete tube worms where the head is mostly concealed by feathery branchiae. They build tubes out of parchment, sand, and bits of shell...
) and a family of deep-sea worms associated with hydrothermal vents (AlvinellidaeAlvinellidaeThe Alvinellidae are a family of small, deep-sea polychaete worms endemic to hydrothermal vents in the Pacific Ocean. Belonging to the order Terebellida, the family contains two genera, Alvinella and Paralvinella; the former genus contains two valid species and the latter eight...
). - the Canalipalpata order belongs to the PolychaetePolychaeteThe Polychaeta or polychaetes are a class of annelid worms, generally marine. Each body segment has a pair of fleshy protrusions called parapodia that bear many bristles, called chaetae, which are made of chitin. Indeed, polychaetes are sometimes referred to as bristle worms. More than 10,000...
classClass (biology)In biological classification, class is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, order, family, genus, and species, with class fitting between phylum and order...
also known as bristle worms. There are more than 10,000 described species of polychaetes; they can be found in nearly every marine environment. Some species live in the coldest ocean temperatures of the abyssal plainAbyssal plainAn abyssal plain is an underwater plain on the deep ocean floor, usually found at depths between 3000 and 6000 metres. Lying generally between the foot of a continental rise and a mid-ocean ridge, abyssal plains cover more than 50% of the Earth’s surface. They are among the flattest, smoothest...
, while others can be found in the extremely hot waters adjacent to hydrothermal ventHydrothermal ventA hydrothermal vent is a fissure in a planet's surface from which geothermally heated water issues. Hydrothermal vents are commonly found near volcanically active places, areas where tectonic plates are moving apart, ocean basins, and hotspots. Hydrothermal vents exist because the earth is both...
s. Polychaetes occur throughout the Earth's oceans at all depths, from forms that live as planktonPlanktonPlankton are any drifting organisms that inhabit the pelagic zone of oceans, seas, or bodies of fresh water. That is, plankton are defined by their ecological niche rather than phylogenetic or taxonomic classification...
near the surface, to a 2–3 cm specimen (still unclassified) observed by the robot ocean probe NereusNereus (underwater vehicle)Nereus is a hybrid autonomous underwater vehicle built by the Woods Hole Oceanographic Institution . Constructed as a research vehicle to operate at depths of up to , it was designed to explore Challenger Deep, the deepest surveyed point in the global ocean...
at the bottom of the Challenger DeepChallenger DeepThe Challenger Deep is the deepest known point in the oceans, with a depth of to by direct measurement from submersibles, and slightly more by sonar bathymetry . It is located at the southern end of the Mariana Trench near the Mariana Islands group...
, the deepest spot in the Earth's oceans. - the Polychaete class belongs to the AnnelidAnnelidThe annelids , formally called Annelida , are a large phylum of segmented worms, with over 17,000 modern species including ragworms, earthworms and leeches...
phylumPhylumIn biology, a phylum The term was coined by Georges Cuvier from Greek φῦλον phylon, "race, stock," related to φυλή phyle, "tribe, clan." is a taxonomic rank below kingdom and above class. "Phylum" is equivalent to the botanical term division....
, also known as also called ringed worms. There are over 17,000 living annelid species, ranging in size from microscopic to the Australian giant Gippsland earthwormGiant Gippsland earthwormThe giant Gippsland earthworm, Megascolides australis, is one of Australia's 1,000 native earthworm species. These Giant earthworms average 1 meter long and 2 cm in diameter and can reach 3 m in length...
, which can grow up to 3 metres (9.8 ft) long.
Species of Serpula
While the higher taxonomy is fairly well understood, the lower taxonomy within the Serpula genus is somewhat confusing, and not yet thoroughly worked out. Earlier sources have described as many as 77 different species and subspecies. However, there are currently only 29 recognized species in the Genus Serpula. The number and names of these species may soon change as a result of an ongoing revision of the genus by taxonomists.- Serpula cavernicola (Fassari & Mollica, 1991), Messina, ItalyItalyItaly , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...
- Serpula columbiana (Johnson, 1901), Puget SoundPuget SoundPuget Sound is a sound in the U.S. state of Washington. It is a complex estuarine system of interconnected marine waterways and basins, with one major and one minor connection to the Strait of Juan de Fuca and the Pacific Ocean — Admiralty Inlet being the major connection and...
, Washington - Serpula concharum (Langerhans, 1880), MadeiraMadeiraMadeira is a Portuguese archipelago that lies between and , just under 400 km north of Tenerife, Canary Islands, in the north Atlantic Ocean and an outermost region of the European Union...
, Mediterranean-Atlantic - Serpula crenata (Ehlers, 1908), ZanzibarZanzibarZanzibar ,Persian: زنگبار, from suffix bār: "coast" and Zangi: "bruin" ; is a semi-autonomous part of Tanzania, in East Africa. It comprises the Zanzibar Archipelago in the Indian Ocean, off the coast of the mainland, and consists of numerous small islands and two large ones: Unguja , and Pemba...
, Indo-West PacificIndo-West PacificThe Indo-West Pacific, or IWP, is a zoogeographical region spanning the entire Indian Ocean including the Red Sea and the Pacific Ocean as far as the Caroline Islands but short of the Marshall Islands...
; bathyal - Serpula granulosa , Kagoshima and Enoshima, Japan, Indo-West Pacific
- Serpula hartmanae (Reish, 1968), BikiniBikiniThe bikini is typically a women's two-piece swimsuit. One part of the attire covers the breasts and the other part covers the crotch and part of or the entire buttocks, leaving an uncovered area between the two. Merriam–Webster describes the bikini as "a woman's scanty two-piece bathing suit" or "a...
, Indo-West Pacific - Serpula indica (Parab & Gaikwad, 1989), IndiaIndiaIndia , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...
- Serpula israelitica (Amoureux, 1976), HaifaHaifaHaifa is the largest city in northern Israel, and the third-largest city in the country, with a population of over 268,000. Another 300,000 people live in towns directly adjacent to the city including the cities of the Krayot, as well as, Tirat Carmel, Daliyat al-Karmel and Nesher...
, Levant Basin, IsraelIsraelThe State of Israel is a parliamentary republic located in the Middle East, along the eastern shore of the Mediterranean Sea... - Serpula japonica (Imajima, 1979), HonshuHonshuis the largest island of Japan. The nation's main island, it is south of Hokkaido across the Tsugaru Strait, north of Shikoku across the Inland Sea, and northeast of Kyushu across the Kanmon Strait...
, JapanJapanJapan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
; possibly SeychellesSeychellesSeychelles , officially the Republic of Seychelles , is an island country spanning an archipelago of 115 islands in the Indian Ocean, some east of mainland Africa, northeast of the island of Madagascar.... - Serpula jukesii , Indo-West Pacific
- Serpula lobiancoi (Rioja, 1917), Mediterranean-Atlantic
- Serpula longituba (Imajima, 1979), Honshu, Japan
- Serpula maorica , New ZealandNew ZealandNew Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...
- Serpula nanhaiensis (Sun & Yang, 2001), South China SeaSouth China SeaThe South China Sea is a marginal sea that is part of the Pacific Ocean, encompassing an area from the Singapore and Malacca Straits to the Strait of Taiwan of around...
- Serpula narconensis , Narcon Island, Antarctica, subantarctic
- Serpula oshimae (Imajima & ten Hove, 1984), Indo-West Pacific
- Serpula pacifica (Uchida, 1978), Sabiura, Japan
- Serpula philippensis (McIntosh, 1885), PhilippinesPhilippinesThe Philippines , officially known as the Republic of the Philippines , is a country in Southeast Asia in the western Pacific Ocean. To its north across the Luzon Strait lies Taiwan. West across the South China Sea sits Vietnam...
; bathyal - Serpula planorbis (Southward, 1963), Irish SeaIrish SeaThe Irish Sea separates the islands of Ireland and Great Britain. It is connected to the Celtic Sea in the south by St George's Channel, and to the Atlantic Ocean in the north by the North Channel. Anglesey is the largest island within the Irish Sea, followed by the Isle of Man...
; bathyal - Serpula rubens (Straughan, 1967), QueenslandQueenslandQueensland is a state of Australia, occupying the north-eastern section of the mainland continent. It is bordered by the Northern Territory, South Australia and New South Wales to the west, south-west and south respectively. To the east, Queensland is bordered by the Coral Sea and Pacific Ocean...
, New South WalesNew South WalesNew South Wales is a state of :Australia, located in the east of the country. It is bordered by Queensland, Victoria and South Australia to the north, south and west respectively. To the east, the state is bordered by the Tasman Sea, which forms part of the Pacific Ocean. New South Wales...
, AustraliaAustraliaAustralia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area... - Serpula sinica (Wu & Chen, 1979), South China Sea
- Serpula tetratropia (Imajima & ten Hove, 1984), PalauPalauPalau , officially the Republic of Palau , is an island nation in the Pacific Ocean, east of the Philippines and south of Tokyo. In 1978, after three decades as being part of the United Nations trusteeship, Palau chose independence instead of becoming part of the Federated States of Micronesia, a...
and Caroline IslandCaroline IslandCaroline Island or Caroline Atoll , is the easternmost of the uninhabited coral atolls which comprise the southern Line Islands in the central Pacific Ocean.... - Serpula uschakovi (Kupriyanova, 1999), Gilderbrandt Island, Sea of JapanSea of JapanThe Sea of Japan is a marginal sea of the western Pacific Ocean, between the Asian mainland, the Japanese archipelago and Sakhalin. It is bordered by Japan, North Korea, Russia and South Korea. Like the Mediterranean Sea, it has almost no tides due to its nearly complete enclosure from the Pacific...
- Serpula vasifera (Haswell, 1885), Port JacksonPort JacksonPort Jackson, containing Sydney Harbour, is the natural harbour of Sydney, Australia. It is known for its beauty, and in particular, as the location of the Sydney Opera House and Sydney Harbour Bridge...
, New South Wales, Australia - Serpula vermicularisSerpula vermicularisSerpula vermicularis, known by common names including the calcareous tubeworm, fan worm, plume worm or red tube worm, is a species of segmented marine polychaete worm in the family Serpulidae. It is the type species of the genus Serpula and was first described by Linnaeus in 1767...
, Western Europe - Serpula vittata (Augener, 1914), Shark BayShark BayShark Bay is a World Heritage listed bay in Western Australia. The term may also refer to:* the locality of Shark Bay, now known as Denham* Shark Bay Marine Park* Shark Bay , a shark exhibit at Sea World, Gold Coast, Australia* Shire of Shark Bay...
, Western AustraliaWestern AustraliaWestern Australia is a state of Australia, occupying the entire western third of the Australian continent. It is bounded by the Indian Ocean to the north and west, the Great Australian Bight and Indian Ocean to the south, the Northern Territory to the north-east and South Australia to the south-east...
; Indo-West Pacific - Serpula watsoni , TrincomaleeTrincomaleeTrincomalee is a port city in Eastern Province, Sri Lanka and lies on the east coast of the island, about 113 miles south of Jaffna. It has a population of approximately 100,000 . The city is built on a peninsula, which divides the inner and outer harbours. Overlooking the Kottiyar Bay,...
, Sri LankaSri LankaSri Lanka, officially the Democratic Socialist Republic of Sri Lanka is a country off the southern coast of the Indian subcontinent. Known until 1972 as Ceylon , Sri Lanka is an island surrounded by the Indian Ocean, the Gulf of Mannar and the Palk Strait, and lies in the vicinity of India and the...
; Indo-West Pacific - Serpula willeyi , Sri Lanka
- Serpula zelandica , New Zealand
Geographic distribution and habitat
Worldwide,very common. PacificPacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...
, Atlantic
Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...
, and Indian
Indian Ocean
The Indian Ocean is the third largest of the world's oceanic divisions, covering approximately 20% of the water on the Earth's surface. It is bounded on the north by the Indian Subcontinent and Arabian Peninsula ; on the west by eastern Africa; on the east by Indochina, the Sunda Islands, and...
oceans, Mediterranean Sea
Mediterranean Sea
The Mediterranean Sea is a sea connected to the Atlantic Ocean surrounded by the Mediterranean region and almost completely enclosed by land: on the north by Anatolia and Europe, on the south by North Africa, and on the east by the Levant...
, North Sea
North Sea
In the southwest, beyond the Straits of Dover, the North Sea becomes the English Channel connecting to the Atlantic Ocean. In the east, it connects to the Baltic Sea via the Skagerrak and Kattegat, narrow straits that separate Denmark from Norway and Sweden respectively...
, Red Sea
Red Sea
The Red Sea is a seawater inlet of the Indian Ocean, lying between Africa and Asia. The connection to the ocean is in the south through the Bab el Mandeb strait and the Gulf of Aden. In the north, there is the Sinai Peninsula, the Gulf of Aqaba, and the Gulf of Suez...
. Species of the Serpula genus are common on the west coast of North America from Alaska
Alaska
Alaska is the largest state in the United States by area. It is situated in the northwest extremity of the North American continent, with Canada to the east, the Arctic Ocean to the north, and the Pacific Ocean to the west and south, with Russia further west across the Bering Strait...
to Baja California
Baja California
Baja California officially Estado Libre y Soberano de Baja California is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is both the northernmost and westernmost state of Mexico. Before becoming a state in 1953, the area was known as the North...
, but are rarely if ever found on the east coast of the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
. They are common in Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
and Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
.
Like most tube-building polychaetes, worms of the Serpula genus are benthic
Benthic zone
The benthic zone is the ecological region at the lowest level of a body of water such as an ocean or a lake, including the sediment surface and some sub-surface layers. Organisms living in this zone are called benthos. They generally live in close relationship with the substrate bottom; many such...
, sedentary suspension feeders
Filter feeder
Filter feeders are animals that feed by straining suspended matter and food particles from water, typically by passing the water over a specialized filtering structure. Some animals that use this method of feeding are clams, krill, sponges, baleen whales, and many fish and some sharks. Some birds,...
. They secrete and inhabit a permanent calcareous
Calcareous
Calcareous is an adjective meaning mostly or partly composed of calcium carbonate, in other words, containing lime or being chalky. The term is used in a wide variety of scientific disciplines.-In zoology:...
tube attached to hard substrata. As they do not travel outside their tubes, these worms do not have any specialized appendages for swimming.
Worms of the Serpula genus are commonly found attached to submerged rocks, shells, and even boats in many coastal areas around the world. They are found at depths ranging from intertidal
Intertidal zone
The intertidal zone is the area that is above water at low tide and under water at high tide . This area can include many different types of habitats, with many types of animals like starfish, sea urchins, and some species of coral...
to at least 800 meters.
Predators include predatory starfish such as the Ochre Sea Star
Ochre Sea Star
Pisaster ochraceus, generally known as the Purple Sea Star, Ochre Sea Star or Ochre Starfish, is a common starfish found among the waters of the Pacific Ocean.-Description:...
(Pisaster ochraceous).
Head
The funnel-shaped, symmetrical peristomium is fused with the prostomiumProstomium
Prostomium is the first body segment in annelid worms. It is in front of the mouth, being usually a small shelf- or lip-like extension over the dorsal side of the mouth. It sometimes bears antennae and eyes. It often functions like a kind of overlip when the animal is feeding...
to form the head, at the anterior end of the body. Worms of the Serpula genus have two photoreceptors or "eyespots" on the peristomium. The prostomium bears a branchial "crown", a specialized mouth appendage which resembles a fan (for which the animals are given the name fanworms).
This crown, which can be extended for feeding and gas exchange, and rapidly retracted when threatened, consists of two bundles (one right and one left) of featherlike gill
Gill
A gill is a respiratory organ found in many aquatic organisms that extracts dissolved oxygen from water, afterward excreting carbon dioxide. The gills of some species such as hermit crabs have adapted to allow respiration on land provided they are kept moist...
s, known as branchiae or radiole
Radiole
A radiole is a heavily ciliated feather-like tentacle found in highly organized clusters on the crowns of Canalipalpata. Canalipalpata is an order of sessile marine polychaete worms consisting of 31 families...
s. Each of these bundles consists of a single row of radioles attached to a branchial stalk and curved into a semicircle. These two semicircles form the funnel-shaped branchial crown. The mouth is at the apex of the funnel between the two branchial stalks.
When extended, these heavily ciliated
Cilium
A cilium is an organelle found in eukaryotic cells. Cilia are slender protuberances that project from the much larger cell body....
radioles trap particles of organic matter and transport it towards the mouth. While they are primarily feeding structures, the radioles also serve as respiratory organs. The radioles of different Serpula species are typically red, pink, or orange in color, with white transverse bands. Astaxanthin
Astaxanthin
Astaxanthin is a carotenoid. It belongs to a larger class of phytochemicals known as terpenes. It is classified as a xanthophyll, which means "yellow leaves". Like many carotenoids, it is a colorful, lipid-soluble pigment. Astaxanthin is found in microalgae, yeast, salmon, trout, krill, shrimp,...
, a carotenoid
Carotenoid
Carotenoids are tetraterpenoid organic pigments that are naturally occurring in the chloroplasts and chromoplasts of plants and some other photosynthetic organisms like algae, some bacteria, and some types of fungus. Carotenoids can be synthesized fats and other basic organic metabolic building...
pigment, is responsible for the bright red color of the crown of S. vermicularis. There are usually about 40 radioles in an adult.
One of these radioles, called an operculum, is a highly specialized structure located on the dorsal part of the head. The operculum consists of a long, thick stalk with a cartilaginous
Cartilage
Cartilage is a flexible connective tissue found in many areas in the bodies of humans and other animals, including the joints between bones, the rib cage, the ear, the nose, the elbow, the knee, the ankle, the bronchial tubes and the intervertebral discs...
, cone-shaped plug at the distal end. This plug can be used to seal the opening of the tube after the animal has retreated inside. The operculum, which is usually red in color, secretes a mucus which seems to possess antibiotic
Antibiotic
An antibacterial is a compound or substance that kills or slows down the growth of bacteria.The term is often used synonymously with the term antibiotic; today, however, with increased knowledge of the causative agents of various infectious diseases, antibiotic has come to denote a broader range of...
properties. It is not unusual for the animal to have two opercula. Both serpulid and sabellid worms have radioles, but sabellids (such as Sabella pavonina
Peacock worm
The peacock worm is a marine polychaete worm belonging to the family Sabellidae. It occurs along the coasts of Western Europe and the Mediterranean. It is found in shallow, tidal waters with a bed of mud, sand or gravel. It is sometimes found on rocks or shipwrecks.It is 10-25 centimetres in...
) lack an operculum.
A single median nephridiopore
Nephridiopore
Nephridiopore is part of the nephridia, an excretory organ found in many organisms, such as flatworms or annelids. Nephridia are analogous to nephrons or uriniferous tubules found in the kidney of humans....
is located dorsally on the head, between the upper lip and a median dorsal papilla. The anterior end of the fecal groove passes over it and urine is released from it into the waste current. Like all serpulids and sabellids, they have only a single pair of metanephridia, which empty via this nephridiopore.
Thorax
The thoracic region of the body consists of seven chaetigersChaeta
A chaeta or cheta is a chitinous bristle or seta found on an insect, arthropod or annelid worms such as the earthworm, although the term is also frequently used to describe similar structures in other invertebrates. The plural form is chaetae or chetae.In the Polychaeta, they are located on the...
(segments bearing chaetae). Chaeta
Chaeta
A chaeta or cheta is a chitinous bristle or seta found on an insect, arthropod or annelid worms such as the earthworm, although the term is also frequently used to describe similar structures in other invertebrates. The plural form is chaetae or chetae.In the Polychaeta, they are located on the...
e are small appendages that aid the worm with mobility. The first of these segments is the collar segment (peristomium), to which the prostomium is attached. The peristomium bears an elaborate, delicate, membranous collar that overlaps the margins of the aperture of the tube and covers the opening of the tube when the head is extended.
There is a pair of calcium-secreting gland
Gland
A gland is an organ in an animal's body that synthesizes a substance for release of substances such as hormones or breast milk, often into the bloodstream or into cavities inside the body or its outer surface .- Types :...
s located near the midventral line on the posterior end of the peristomium. These glands open onto the "ventral shields", which are wide glandular pads on the ventral side of the anterior thoracic segments. The ventral shields secrete organic
Organic matter
Organic matter is matter that has come from a once-living organism; is capable of decay, or the product of decay; or is composed of organic compounds...
material and use this, combined with the calcium secreted by the glands, to form a paste from which the tube is made.
These white calcareous
Calcareous
Calcareous is an adjective meaning mostly or partly composed of calcium carbonate, in other words, containing lime or being chalky. The term is used in a wide variety of scientific disciplines.-In zoology:...
tubes are made of both calcite
Calcite
Calcite is a carbonate mineral and the most stable polymorph of calcium carbonate . The other polymorphs are the minerals aragonite and vaterite. Aragonite will change to calcite at 380-470°C, and vaterite is even less stable.-Properties:...
and aragonite
Aragonite
Aragonite is a carbonate mineral, one of the two common, naturally occurring, crystal forms of calcium carbonate, CaCO3...
. They are usually smooth with faint longitudinal ridges, curved but not strongly coiled, and are rarely more than 12 cm in length. The tube appears to be shaped by the ventral shields and by a collar which is just behind the head.
There is a median, longitudinal, ciliated, thoracic fecal groove on the dorsal midline of the thorax. It is a broad, shallow, relatively indistinct trough running the length of the thorax and ending at the head.
Abdomen
Worms of the Serpula genus have a distinct abdominal region, composed of up to 190 very short, wide segments. The terminal body region is the tiny pygidiumPygidium
The pygidium is the posterior body part or shield of crustaceans and some other arthropods, such as insects and the extinct trilobites. It contains the anus and, in females, the ovipositor...
, on which the anus
Anus
The anus is an opening at the opposite end of an animal's digestive tract from the mouth. Its function is to control the expulsion of feces, unwanted semi-solid matter produced during digestion, which, depending on the type of animal, may be one or more of: matter which the animal cannot digest,...
is located. A fecal groove extends the length of the ventral midline of the abdomen. The fecal groove spirals across to the dorsal position as it reaches the thoracic region.
Vertical ciliary tracts in the grooves between adjacent abdominal segments move particles toward the abdominal fecal groove. Once in the abdominal fecal groove, further ciliary currents transport particulate matter (feces, gametes, etc.) from the depths of the tube, through the thoracic segment to the aperture where it can be released to the sea.
Vasculature
Worms of the Serpula genus have a very unusual dual circulatory system, consisting of a central system of large vessels through which a continuous true circulation of blood is maintained, and also a peripheral system of small, predominantly blind-ending vessels which alternately empty and fill in a tidal fashion.In the central circulatory system, the blood moves anteriorly from the tip of the abdomen to the front of the thorax through a sinus enveloping the alimentary canal, and posteriorly through a ventral blood vessel. The ventral vessel and the sinus communicate with each other by segmentally arranged ring vessels, and by a dorsal vessel, a transverse
Transverse plane
The transverse plane is an imaginary plane that divides the body into superior and inferior parts. It is perpendicular to the coronal and sagittal planes....
vessel, and a pair of circumesophageal
Esophageal
Esophageal can refer to:* The esophagus* Esophageal arteries* Esophageal glands...
vessels situated at the anterior end of the thorax. The dorsal vessel in some of the larger serpulids, like Serpula, possesses a valve and a muscular sphincter
Sphincter
A sphincter is an anatomical structure, or a circular muscle, that normally maintains constriction of a natural body passage or orifice and which relaxes as required by normal physiological functioning...
, probably to prevent backflow of blood from the transverse vessel.
The blood circulation in the periphery, especially the radiole, is especially unusual. Instead of venous and arterial blood flowing through afferent
Afferent
Afferent is an anatomical term with the following meanings:*Conveying towards a center, for example the afferent arterioles conveying blood towards the Bowman's capsule in the Kidney. Opposite to Efferent.*Something that so conducts, see Afferent nerve fiber...
and efferent
Efferent
Efferent is an anatomical term with the following meanings:*Conveying away from a center, for example the efferent arterioles conveying blood away from the Bowman's capsule in the kidney. Opposite to afferent....
vessels within the radiole, there is a single branchial sinus through which blood flows in both directions, in a tidal fashion. The vessels of the peripheral system receive their blood from the central system, returning it back along the same channels (i.e., these channels serve in both afferent and efferent directions).
The peripheral circulatory system has the following components: the two branchial vessels and their branches in the crown; the periesophageal vascular plexus
Plexus
A plexus is a part of nervous system. Plexus has a slightly different definition in vertebrates and in invertebrates.- In vertebrates :In vertebrates, a plexus is an area where nerves branch and rejoin. The electrical signals do not mix; rather, the fibres travel together with their electrical...
es; the vessels of the collar and lips; the vessels supplying the body wall, thoracic membrane, and parapodia. The single vessels in each radiole of the branchial crown, and the vessels of opercula, are all branches of the two branchial vessels.
When the crown is retracted inside the tube, the radioles and operculum cease to function as a respiratory organ. The movement of blood in the capillaries of the thoracic membrane and body wall continues, however. Under these circumstances, respiratory exchange is probably carried out between the blood in these vessels and the surrounding water, which is kept moving through the tube by vigorous pumping movements of the abdomen and also by the activity of the ciliary tracts.
Oxygen transport mechanisms
The well-developed longitudinalLongitudinal
Longitudinal may refer to:* Longitudinal engine, an internal combustion engine in which the crankshaft is oriented along the long axis of the vehicle, front to back...
muscles of the body wall of serpulids lack a special blood supply. The body surface in the larger serpulids, like Serpula, has a rich blood supply, and the water in contact with this surface is constantly renewed. It seems probable that the outer body surface of serpulids serves as a respiratory membrane
Biological membrane
A biological membrane or biomembrane is an enclosing or separatingmembrane that acts as a selective barrier, within or around a cell. It consists of a lipid bilayer with embedded proteins that may constitute close to 50% of membrane content...
, supplying oxygen to the underlying muscles by diffusion
Diffusion
Molecular diffusion, often called simply diffusion, is the thermal motion of all particles at temperatures above absolute zero. The rate of this movement is a function of temperature, viscosity of the fluid and the size of the particles...
.
The biochemistry of the blood of Serpula is especially unusual in that the blood contains not only hemoglobin, but also chlorocruorin
Chlorocruorin
Chlorocruorin is an oxygen-binding hemeprotein present in the blood plasma of many annelids, particularly certain marine polychaetes. Its affinity for oxygen is weaker than that of most hemoglobins...
. While all sabellids and serpulids employ chlorocruorin as an oxygen transport macromolecule, Serpula is the only genus that appears to possess both hemoglobin as well as chlorocruorin.
Chlorocruorin is an oxygen-binding hemeprotein whose affinity for oxygen is weaker than that of most hemoglobin
Hemoglobin
Hemoglobin is the iron-containing oxygen-transport metalloprotein in the red blood cells of all vertebrates, with the exception of the fish family Channichthyidae, as well as the tissues of some invertebrates...
s. A dichromatic
Dichromatism
Dichromatism is a phenomenon where the hue of the colour in materials or solutions are dependent on both the concentration of the absorbing substance and the depth or thickness of the medium traversed...
compound, chlorocruorin is noted for appearing green in dilute solutions, though it appears light red when found in concentrated solutions. Its structure is very similar to erythrocruorin
Erythrocruorin
Erythrocruorin is a large oxygen-carrying protein, whose molecular mass is greater than 3.5 million Daltons. It is related to the similar chlorocruorin. It is found in many annelids.- References :*, PNAS June 20, 2000. Accessed July 17, 2007....
, each molecule being composed of more than a hundred interlinked 16-17kDa
Atomic mass unit
The unified atomic mass unit or dalton is a unit that is used for indicating mass on an atomic or molecular scale. It is defined as one twelfth of the rest mass of an unbound neutral atom of carbon-12 in its nuclear and electronic ground state, and has a value of...
myoglobin-like subunits arranged in a giant complex with a total weight exceeding 3600kDa
KDA
KDA may refer to:* Karachi Development Authority* Kongsberg Defence & Aerospace* Kotelawala Defence Academy* Kramer Design Associates* Lithium diisopropylamide, KDA is the potassium analogue of lithium diisopropylamideOr kDa may refer to:...
. This enormous macromolecule
Macromolecule
A macromolecule is a very large molecule commonly created by some form of polymerization. In biochemistry, the term is applied to the four conventional biopolymers , as well as non-polymeric molecules with large molecular mass such as macrocycles...
is free floating in the plasma, and not contained within red blood cells.
The ratio of plasma hemoglobin to chlorocruorin is high in younger individuals, but this ratio reverses as the animal matures. Presumably this reflects a lower oxygen consumption in the adult worm, relative to the juveniles.
Nervous system
Like other annelids, these worms possess well-developed nervous systems. The nervous system consists of a central brain in the upper part of the head, which is relatively large compared with that of other annelids. Extending from the brain is a large ventral nerve cord running the length of the body. There are many supporting gangliaGanglion
In anatomy, a ganglion is a biological tissue mass, most commonly a mass of nerve cell bodies. Cells found in a ganglion are called ganglion cells, though this term is also sometimes used to refer specifically to retinal ganglion cells....
along the length of this cord (including pleural, pedal and cerebral ganglia), and a series of small nerves in each body segment. Signals transmitted through the pedal ganglia allow the worms to retract rapidly into their tube if threatened.
Reproductive system
Sexes are separate. Like other annelids, the coelomCoelom
The coelom is a fluid-filled cavity formed within the mesoderm. Coeloms developed in triploblasts but were subsequently lost in several lineages. Loss of coelom is correlated with reduction in body size...
stores and provides nutrients for gametes. When they reproduce, they simply shed their gametes straight into the water where the ova and spermatozoa become part of the zooplankton
Zooplankton
Zooplankton are heterotrophic plankton. Plankton are organisms drifting in oceans, seas, and bodies of fresh water. The word "zooplankton" is derived from the Greek zoon , meaning "animal", and , meaning "wanderer" or "drifter"...
and are carried by the currents to new sites, where the juvenile worms settle into the substrate. Length of the planktonic stage is unknown but comparison with other serpulids suggests it may be between six days and two months, although in other species the period has been shown to vary with season, salinity or food availability, and delayed settling may cause reduced discrimination of substrata during settling (see ten Hove, 1979 for additional references).
Digestive system
Worms of the Serpula genus are filter feederFilter feeder
Filter feeders are animals that feed by straining suspended matter and food particles from water, typically by passing the water over a specialized filtering structure. Some animals that use this method of feeding are clams, krill, sponges, baleen whales, and many fish and some sharks. Some birds,...
s, and possess a complete digestive system. Like other polychaetes, Serpula excrete with fully developed nephridia
Nephridium
A Nephridium is an invertebrate organ which occurs in pairs and function similar to kidneys. Nephridia remove metabolic wastes from an animal's body. They are present in many different invertebrate lines. There are two basic types, metanephridia and protonephridia, but there are other...
.
Gallery
Click here to see more photographs of various specimens of the Serpula genus.See also
- EumetazoaEumetazoaEumetazoa is a clade comprising all major animal groups except sponges, placozoa and several other little known animals. Characteristics of eumetazoans include true tissues organized into germ layers, and an embryo that goes through a gastrula stage...
- BilateriaBilateriaThe bilateria are all animals having a bilateral symmetry, i.e. they have a front and a back end, as well as an upside and downside. Radially symmetrical animals like jellyfish have a topside and downside, but no front and back...
- Protostomia
- SpiraliaSpiraliaSpiralia is a grouping of animals."Lophotrochozoan" and "spiralian" are sometimes considered equivalent.It receives its name from the spiral cleavage found in most members....
- LophotrochozoaLophotrochozoaThe Lophotrochozoa are a major grouping of protostome animals. The taxon was discovered based on molecular data. Molecular evidence such as a result of studies of the evolution of small-subunit ribosomal RNA supports the monophyly of the phyla listed in the infobox shown at right.-Terminology:The...
- TrochophoreTrochophoreA trochophore is a type of free-swimming planktonic marine larva with several bands of cilia.By moving their cilia rapidly, a water eddy is created. In this way they control the direction of their movement...
External links
- Zipcodezoo.com: Serpula vermicularis
- Raffles Museum of Biodiversity Research: Polychaete Families of Singapore: Serpulidae
- Annelida.net: About Family Serpulidae polychaetes in New Zealand. Accessed 1 May 2010.
- Chamberlin, Ralph V. 1920. The Polychaetes Collected by the Canadian Arctic Expedition, 1913-18. Report of the Canadian Arctic Expedition 9. Annelids, parasitic worms, Protozoans, etc. (B. Polychaeta): 1-41. Pl.1-6. Thomas Mulvey. Ottawa.
- ITIS database, available online at http://www.itis.gov
- Hartmann-Schröder, G. (1996). Annelida, Borstenwürmer, Polychaeta [Annelida, bristleworms, Polychaeta]. 2nd revised ed. The fauna of Germany and adjacent seas with their characteristics and ecology, 58. Gustav Fischer: Jena, Germany. ISBN 3-437-35038-2. 648 pp. (look up in IMIS)