Megascolecidae is a

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

earthworms An earthworm is a soil-dwelling terrestrial animal, terrestrial invertebrate that belongs to the phylum Annelida. The term is the common name for the largest members of the class (biology), class (or subclass (biology), subclass, depending on ...

native to Madagascar, Australia, New Zealand, Asia, and North America. At up to 2 meters in length, their large size distinguishes the Megascolecidae from other earthworm families. They are an essential part of maintaining

soil structure In geotechnical engineering, soil structure describes the arrangement of the solid parts of the soil and of the Pore space in soil, pore space located between them. It is determined by how individual soil granules clump, bind together, and Soil a ...

, minor

carbon sequestration Carbon sequestration is the process of storing carbon in a carbon pool. It plays a crucial role in Climate change mitigation, limiting climate change by reducing the amount of Carbon dioxide in Earth's atmosphere, carbon dioxide in the atmosphe ...

, and maintaining

terrestrial ecosystem Terrestrial ecosystems are ecosystems that are found on land. Examples include tundra, taiga, temperate deciduous forest, tropical rain forest, grassland, deserts. Terrestrial ecosystems differ from aquatic ecosystems by the predominant presen ...

Physiological features

Different

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

of the Megascolecidae have different physiological features, but some similarities of physiological features can be found between species. The family contains relatively large individuals. The length of earthworms can vary from to . The number of

spermatheca The spermatheca (pronounced : spermathecae ), also called ''receptaculum seminis'' (: ''receptacula seminis''), is an organ of the female reproductive tract in insects, e.g. ants, bees, some molluscs, Oligochaeta worms and certain other in ...

l pores is normally paired, but multiples can be present in some species. The location of spermathecal pores and how they are positioned in different segmental locations is used in the identification of different megascolecidids. Earthworms ingest a variety of organic materials in the soil since they live in terrestrial environments. Earthworms in this

have the ability to decompose

lignocellulose Lignocellulose refers to plant dry matter (biomass), so called lignocellulosic biomass. It is the most abundantly available raw material on the Earth for the production of Biofuel, biofuels. It is composed of two kinds of carbohydrate polymers, c ...

, which requires assistance from

microorganisms A microorganism, or microbe, is an organism of microscopic size, which may exist in its single-celled form or as a colony of cells. The possible existence of unseen microbial life was suspected from antiquity, with an early attestation in ...

in their

digestive system The human digestive system consists of the gastrointestinal tract plus the accessory organs of digestion (the tongue, salivary glands, pancreas, liver, and gallbladder). Digestion involves the breakdown of food into smaller and smaller compone ...

. Aside from microorganisms,

digestive enzymes Digestive enzymes take part in the chemical process of digestion, which follows the mechanical process of digestion. Food consists of macromolecules of proteins, carbohydrates, and fats that need to be broken down chemically by digestive enzymes ...

such as

amylase An amylase () is an enzyme that catalysis, catalyses the hydrolysis of starch (Latin ') into sugars. Amylase is present in the saliva of humans and some other mammals, where it begins the chemical process of digestion. Foods that contain large ...

and

cellulase Cellulase (; systematic name 4-β-D-glucan 4-glucanohydrolase) is any of several enzymes produced chiefly by fungi, bacteria, and protozoans that catalyze cellulolysis, the decomposition of cellulose and of some related polysaccharides: : Endo ...

, and

proteins Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, re ...

can be found in different regions of the gut. Chemical digestion mainly occurs in the intestinal caeca of earthworms, which have higher

protease A protease (also called a peptidase, proteinase, or proteolytic enzyme) is an enzyme that catalysis, catalyzes proteolysis, breaking down proteins into smaller polypeptides or single amino acids, and spurring the formation of new protein products ...

activity than other parts of the gut. Genital markings in the Megascolecidae family can be used to distinguish species.

Reproductive system

The Megascolecidae are

oviparous Oviparous animals are animals that reproduce by depositing fertilized zygotes outside the body (i.e., by laying or spawning) in metabolically independent incubation organs known as eggs, which nurture the embryo into moving offsprings kno ...

, laying eggs to reproduce. They are biparental. The ideal condition of

reproduction Reproduction (or procreation or breeding) is the biological process by which new individual organisms – "offspring" – are produced from their "parent" or parents. There are two forms of reproduction: Asexual reproduction, asexual and Sexual ...

for the megascolecidids is 25 °C, where the eggs hatch the quickest and have the highest cocoon production. The male reproductive organ of the Megascolecidae includes testes, seminal vesicles, spermathecae, prostate glands, and spermathecal pores. The sperm can be found in testes and seminal vesicles, but cannot be found in spermathecae. The female reproductive organ consists of female pores, which normally occur in pairs. Both male and female reproductive organs are present in earthworms because they are

monoecious Monoecy (; adj. monoecious ) is a sexual system in seed plants where separate male and female cones or flowers are present on the same plant. It is a monomorphic sexual system comparable with gynomonoecy, andromonoecy and trimonoecy, and contras ...

. To breed, two earthworms exchange sperm. Long after they are separated, the egg case is secreted. It forms a ring around the worm, then the worm removes the ring from its body and injects its own eggs and the other worm's sperm into it. Afterwards, the egg case is sealed and ready to hatch, grow, and become a cocoon.

Lifecycle

The Megascolecidae lifecycle takes around 50–57 days, depending on the external environments and

habitat In ecology, habitat refers to the array of resources, biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species' habitat can be seen as the physical manifestation of its ...

. The rate of growth during the first 14 days is very low, however; after 21 – 28 days, the rate of growth increases and then cycles up and down throughout the worm's life with no pattern. The growth rate of these worms is correlated to the

temperature Temperature is a physical quantity that quantitatively expresses the attribute of hotness or coldness. Temperature is measurement, measured with a thermometer. It reflects the average kinetic energy of the vibrating and colliding atoms making ...

of their environment. As temperatures increase from 30 °C, a significant growth rate and decreasing the time to sexual maturity are seen. The ideal living temperature of megascolecidids is around 15 to 30 °C. Overall mean growth is 1.79 mg/day, 1.57 mg/day, and 1.34 mg/day depending on the abundance of worms and environment condition and size. The cocoon production of Megascolecidae species also is correlated with the temperature of the environment.

Distribution and habitat

Megascolecidae species can be in Australia,

New Zealand New Zealand () is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and List of islands of New Zealand, over 600 smaller islands. It is the List of isla ...

, Asia, North America, South America, and Europe. The intercontinental presence of Megascolecidae species can be explained by the Permanence of Continent Theory, which provides the explanation of most Cenozoic distributions; this theory,though, does not explain the presence of European Megascolecidae in North America. The intercontinental distribution of Megascolecidae has two different theories that explains its phenomenon -land bridges and continental drift.Reynolds, J.W. 1995. The distribution of earthworms (Annelida, Oligochaeta) in North America. Pp. 133- 153 In: Mishra, P.C., N. Behera, B.K. Senapati and B.C. Guru (eds.). Advances in Ecology and Environmental Sciences. New Delhi: Ashish Publishing House, 651 pp. The Megascolecidae family originated in Australia. Australia has number of species that are native to different parts of the country; ''Anisochaeta sebastiani'' is an example. This species can be found from

Queensland Queensland ( , commonly abbreviated as Qld) is a States and territories of Australia, state in northeastern Australia, and is the second-largest and third-most populous state in Australia. It is bordered by the Northern Territory, South Austr ...

Tasmania Tasmania (; palawa kani: ''Lutruwita'') is an island States and territories of Australia, state of Australia. It is located to the south of the Mainland Australia, Australian mainland, and is separated from it by the Bass Strait. The sta ...

. Fifty-three known species of these earthworms can be found in

Western Australia Western Australia (WA) is the westernmost state of Australia. It is bounded by the Indian Ocean to the north and west, the Southern Ocean to the south, the Northern Territory to the north-east, and South Australia to the south-east. Western Aust ...

; ''Graliophilus georgei'' and ''G. secundus'' are some examples. ''G. zeilensis'' can be found in the Northern Territory, specifically in Mount Zeil, West MacDonnell Ranges. ''G. zeilensis'' also can be found on the highest point of the mountain where average rainfall of the region is 250 mm annually. This distinguishes them from other species from ''Graliophilus''. ''Metaphire'' and '' Amynthas'' are two common genera belonging to the Megascolecidae family. They can be found in different countries in Asia. Eight different species of ''Metaphire'' can be found in

Malaysia Malaysia is a country in Southeast Asia. Featuring the Tanjung Piai, southernmost point of continental Eurasia, it is a federation, federal constitutional monarchy consisting of States and federal territories of Malaysia, 13 states and thre ...

: ''M. sedimensis, M. hijaunensis'', ''M..e songkhlaensis, M. pulauensis'', ''M. pulauensis'', ''M. fovella'', ''M. balingensis'', and ''M. strellana''. These species are commonly found in

soil Soil, also commonly referred to as earth, is a mixture of organic matter, minerals, gases, water, and organisms that together support the life of plants and soil organisms. Some scientific definitions distinguish dirt from ''soil'' by re ...

containing medium to high organic material. such as loamy soil. In

Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania, between the Indian Ocean, Indian and Pacific Ocean, Pacific oceans. Comprising over List of islands of Indonesia, 17,000 islands, including Sumatra, ...

, 9 different genera can be found; '' Amynthas'', ''Archipheretima'', ''Metaphire'', ''Metapheretima'', '' Pheretima'', '' Pithemera'', ''Planapheretima, Pleinogaster'', and ''Polypheretima.'' ''Pheretimoid'' is the biggest group of species, which consists of 65 species. Some intrageneric groups are restricted to mainland Asia, but others are native to Indo-Australian Archipelago. The ideal habitat for Megascolecidae is a terrestrial environment with soil with a high content of organic material, such as loamy soil, cattlebor pig manure, and aerobically digested sewage sludge. Megascolecidae species grow and produce more cocoons during the

summer Summer or summertime is the hottest and brightest of the four temperate seasons, occurring after spring and before autumn. At or centred on the summer solstice, daylight hours are the longest and darkness hours are the shortest, with day ...

than the

winter Winter is the coldest and darkest season of the year in temperate and polar climates. It occurs after autumn and before spring. The tilt of Earth's axis causes seasons; winter occurs when a hemisphere is oriented away from the Sun. Dif ...

, because their lifecycle is highly correlated to the temperature and humidity of the environment. Some Megascolecidae species have adapted to colder temperatures and drier areas, though, which enables them to live in higher-altitude regions of the land.

Ecology

Megascolecidae form an important part of the soil ecosystem, in that they indicate soil health and maintain soil productivity. The abundance of earthworms is highly correlated to soil pH, texture, water content, and temperature. Earthworms have the ability to biomonitor soil pollutants. This is because of earthworms' burrowing habit serves to facilitate water flow and agrochemicals through the soil profile, so are able to perform

and reduce soil pollutants]. Invasive earthworms can have a significant impact causing changes in soil profiles, nutrient and organic matter content and other soil organisms or

plant communities A plant community is a collection or Association (ecology), association of plant species within a designated geographical unit, which forms a relatively uniform patch, distinguishable from neighboring patches of different vegetation types. The comp ...

. In most cases the disturbed areas includes

agricultural Agriculture encompasses crop and livestock production, aquaculture, and forestry for food and non-food products. Agriculture was a key factor in the rise of sedentary human civilization, whereby farming of domesticated species created f ...

systems or previously areas that are lacking of earthworms would see the biggest impact of the invasive earthworms. The impact of earthworms on soil structure is due to the rate of net nitrogen mineralization.

Genera

* '' Aceeca'' Blakemore, 2000 * '' Aridulodrilus''

Dyne The dyne (symbol: dyn; ) is a derived units of measurement, unit of force (physics), force specified in the centimetre–gram–second system of units, centimetre–gram–second (CGS) system of units, a predecessor of the modern International S ...

, 2021Records of the Australian Museum (2021) vol. 73, issue no. 4, pp. 123–129 https://doi.org/10.3853/j.2201-4349.73.2021.1769 * '' Amphimiximus'' Blakemore, 2000 * '' Amynthas'' Kinberg, 1867 * '' Anisochaeta'' Beddard, 1890 * '' Anisogogaster'' Blakemore, 2010 * '' Aporodrilus'' Blakemore, 2000 * '' Archipheretima'' Michaelsen, 1928 * '' Arctiostrotus'' McKey-Fender, 1982 * '' Argilophilus'' Eisen, 1893 * '' Austrohoplochaetella'' Jamieson, 1971 * '' Begemius'' Easton, 1982 * '' Caecadrilus'' Blakemore, 2000 * '' Chetcodrilus'' Fender & McKey-Fender, 1990 * '' Comarodrilus'' Stephenson, 1915 * '' Cryptodrilus'' Fletcher, 1886 * '' Dendropheretima'' James, 2005 * '' Deodrilus'' Beddard, 1890 * '' Didymogaster'' Fletcher, 1886 * '' Digaster'' Perrier, 1872 * '' Diporochaeta'' Beddard, 1890 * '' Drilochaera'' Fender & McKey-Fender, 1990 * '' Driloleirus'' Fender & McKey-Fender, 1990 * '' Duplodicodrilus'' Blakemore, 2008 * '' Eastoniella'' Jamieson, 1977 * '' Fletcherodrilus'' Michaelsen, 1891 * '' Gastrodrilus'' Blakemore, 2000 * '' Gemascolex'' Edmonds & Jamieson, 1973 * '' Geofdyneia'' Jamieson, 2000 * '' Graliophilus'' Jamieson, 1971 * '' Haereodrilus'' Dyne, 2000 * '' Healesvillea'' Jamieson, 2000 * '' Heteroporodrilus'' Jamieson, 1970 * '' Hiatidrilus'' Blakemore, 1997 * '' Hickmaniella'' Jamieson, 1974 * '' Hypolimnus'' Blakemore, 2000 * '' Isarogoscolex'' James, 2005 * '' Kincaidodrilus'' McKey-Fender, 1982 * '' Lampito'' Kinberg, 1867 * '' Macnabodrilus'' Fender & McKey-Fender, 1990 * '' Megascolex'' Templeton, 1844 * '' Megascolides'' McCoy, 1878 * '' Metapheretima'' Michaelsen, 1928 * '' Metaphire'' Sims & Easton, 1972 * '' Nelloscolex'' Gates, 1939 * '' Nephrallaxis'' Fender & McKey-Fender, 1990 * '' Notoscolex'' Fletcher, 1886 * '' Oreoscolex'' Jamieson, 1973 * '' Paraplutellus'' Jamieson, 1972 * '' Pericryptodrilus'' Jamieson, 1977 * '' Perionychella'' Michaelsen, 1907 * '' Perionyx'' Perrier, 1872 * '' Perissogaster'' Fletcher, 1887 * '' Pheretima'' Kinberg, 1867 * '' Pithemera'' Sims & Easton, 1972 * '' Planapheretima'' Michaelsen, 1934 * '' Pleionogaster'' Michaelsen, 1892 * '' Plutelloides'' Jamieson, 2000 * '' Plutellus'' Perrier, 1873 * '' Polypheretima'' Michaelsen, 1934 * '' Pontodrilus'' Perrier, 1874 * '' Propheretima'' Jamieson, 1995 * '' Provescus'' Blakemore, 2000 * '' Pseudocryptodrilus'' Jamieson, 1972 * '' Pseudonotoscolex'' Jamieson, 1971 * '' Retrovescus'' Blakemore, 1998 * '' Scolecoidea'' Blakemore, 2000 * ''Sebastianus'' Blakemore, 1997 * '' Simsia'' Jamieson, 1972 * '' Spenceriella'' Michaelsen, 1907 * '' Tassiedrilus'' Blakemore, 2000 * '' Terrisswalkerius'' Jamieson, 1994 * '' Tonoscolex'' Gates, 1933 * '' Torresiella'' Dyne, 1997 * '' Toutellus'' Fender & McKey-Fender, 1990 * '' Troyia'' Jamieson, 1977 * '' Vesiculodrilus'' Jamieson, 1973 * '' Woodwardiella'' Stephenson, 1925 * '' Zacharius'' Blakemore, 1997

References

External links

* {{Authority control Haplotaxida Annelid families