James H. Thorp, ... Lawrence L. Lovell, in Thorp and also Covich's Freshwater Invertebrates (Fourth Edition), 2016

Terminology and also Morphology

Knowledge of only 5 morphological state is forced at this higher level: annuli, chaetae (also order chaete), clitellum, parapodia, and peristomium. Annuli are ring-like body segments. Chaetae space bristles which can have various shapes, depending upon the taxon. A clitellum is a change of the epidermis, which establishes as an conveniently visible, glandular girdle partially behind the woman pores; the secretes a cocoon in i beg your pardon eggs space laid. Parapodia space paired, unjointed lateral appendages uncovered in polychaete worms, which are often fleshy (especially in maritime polychaetes) and also used because that locomotion, respiration, and other functions. The peristomium is the 2nd body segment of annelids. It might be linked with the anterior segment, or prostomium.

You are watching: What is the purpose of the clitellum


View chapterPurchase book
Read full chapter
URL: https://www.smashville247.net/science/article/pii/B9780123850287000123

Comparative Reproduction


Susan D. Hill, ... Daniel H. Shain, in Encyclopedia of Reproduction (Second Edition), 2018

Cocoon Production

In coordination with egg laying, clitellates secrete a proteinaceous cocoon that gives a microenvironment because that embryonic advance (Coleman and Shain, 2009). The process initiates by the proliferation of clitellum-specific granular cells that distinguish into 2 cell types, among which makes fibrous protein the builds the cocoon wall surface and one more that secretes a glue-like problem to seal the cocoon ends. Numerous million granules of each material kind (i.e., cocoon wall, glue) are vital to construct a solitary cocoon. Secreted wall surface granules at first self-assemble to form a sheath around the clitellum. Top top the relax of eggs and cocoon fluid from the woman pore into the sheath, the worm pulls its head with while concurrently sealing both end of the sheath v granulated structures referred to as opercula (Sawyer, 1986). In part leeches (e.g., Helobdella), the cocoon is secreted from a ring of granular cells surrounding the mrs pore and also forms a sac the is sealed through a solitary operculum. Commonly only a few cocoons are secreted over the course of number of hours, yet up come ∼50 have actually been report in part worms (e.g., Myzobdella lugubris). The variety of eggs deposited right into each cocoon ranges from one to an ext than 100, depending on the species.


Clitellate cocoons display screen a selection of morphologies (Fig. 5) however fall right into three basic categories: hard-shelled, membranous and gelatinous (Siddall and Burreson, 1996). These are distinguished mostly by the thickness that the fibrous cocoon wall. In some terrestrial taxa (e.g., Hirudo, Haemopis), a spongy matrix surrounds the cocoon and also appears to protect against dessication through trapping water droplets. The contents of clitellate cocoons screen extraordinary physiochemical properties (e.g., thermal, chemical resilience), making them beneficial resources together biomaterials and also bioadhesives.



Fredric R. Govedich, william E. Moser, in Thorp and also Covich's Freshwater Invertebrates (Fourth Edition), 2015

Reproduction

All leeches are hermaphrodites, mirroring either protandry or cosexuality (Davies and Singhal, 1988), v reciprocal cross-fertilization together the general rule. Fertilization, i beg your pardon is internal, is completed in most Glossiphoniidae and also all Piscicolidae and Erpobdellidae by it is registered a spermatophore to the partner’s body. Spermatozoa penetrate the body wall and do their way to the ovisacs via the coelomic sinuses (Sawyer, 1986; Govedich et al., 2009). The clitellar region is the most constant site because that the deposition that spermatophores, yet they can be attached to any part of the body. In some types of Piscicolidae, a specialized region exists because that reception that spermatophores; fertilization is successful only by spermatophores deposited there. In Hirudiniformes, reciprocal interior fertilization is brought around by the insertion of one eversible cock into the partner’s vagina.

Once fertilization occurs, eggs space deposited into a cocoon secreted by the clitellum (Figure 23.10). There can be a considerable hold-up between copulation and cocoon deposition. Because that example, in field populations the H. Stagnalis, copulation wake up in the fall and cocoon deposition takes ar in the feather (Davies and Reynoldson, 1976). It has been commonly assumed that the visibility of a clearly shows clitellum carefully parallels mature of the woman reproductive system; and in nonreproductive leeches, the clitellar glands are barely distinguishable indigenous the epithelial cell (Fernandez et al., 1992). The clitellum is particularly prominent in Erpobdellidae. Biernacka and also Davies (1995) verified that sexual maturity that E. Obscura cannot be judged by the presence or absence of one externally visible clitellum. Return a high proportion of the population exhibited a visible clitellum at part time, the was not persistent, lasting no much longer than 7 days. Feeding regime affects the timing of the clitellum development; but regardless that feeding regime, all leeches displayed two durations with a clearly shows clitellum. The first appearance the a clitellum did not coincide through either spermatogenic or oogenic maturity; yet at the 2nd appearance of a clitellum, fully mature ova were present. The visibility of a clearly shows clitellum is for this reason not a an excellent indicator of maturity in E. Obscura and also probably not a great indicator in many or all species of Erpobdellidae. The existence of a spermatophore is also not a good indicator that maturity. Singhal et al. (1985) uncovered that just 5% of maturation E. Obscura collected from the ar had observable spermatophores, and also Biernacka and Davies (1995) found that just 4% the the mature-size-range animals had a spermatophore attached.

Erpobdellid cocoons are thick-walled, oval (Figure 23.10), and attached come a firm substrate (stone, leaf, stem, wood). Cocoons the Barbronia weberi are comparable and are often attached to the pipeline of water plants (Govedich et al., 2003). The cocoons that Piscicolidae and also Hirudiniformes are just loosely attached come the substrate and also are commonly spherical. Species of Hirudiniformes deposit your cocoons in moist habitats the end of water; the outer wall of the cocoon is spongy, i beg your pardon is thought to mitigate water loss. The cocoons of Glossiphoniidae are very thin-walled and are one of two people deposited top top the substrate and also immediately covered by the parent’s body or attached to the ventral surface of the parent (Fig. 23.10). In both cases, the hatchlings room attached to the ventral body wall surface and are carried approximately by the parental for a long period. For Theromyzon tessulatum Müller, 1774, this deserve to be five months; and for Theromyzon trizonare, this deserve to be one month (Wilkialis and Davies, 1980a). Glossiphonia complanata adults administer their young through nutrients that space passed through the body wall of the parent right into the posterior sucker of the young (de Eguileor et al., 1994). Reduce in human body weight and size have been recorded for brooding glossiphoniids; however, these losses have actually been meeting to decreased feeding potentials and also to the energy expended ventilating the young (Calow and also Riley, 1982; Milne and Calow, 1990). It is possible that other types that brood fastened young may administer nutrients come the occurring young; however, further studies must be conducted on a selection of glossiphoniid leech species. A compare of reproductive calculation for glossiphoniids the brood eggs and young and for erpobdellids that deposit egg in a cocoon reflects that brooding is no metabolically much more expensive 보다 encapsulation. There space no extra energy costs incurred in regards to carrying or ventilating broods, but weight loss because of reduction in feeding occurs. This costs show up to be energetically comparable to the price of encapsulation for erpobdellids; and also therefore, brooding and encapsulation represent alternative evolutionary courses for brood protection.


Globally, some 6000 earthworm species have been described, present under a range of climatic regimes native boreal to tropical biomes (Butt and Lowe, 2011). Every earthworms have a comparable life cycle. After ~ a duration of weeks come months, one earthworm cocoon will certainly hatch in the soil or sheet litter to produce a hatchling worm. This animal is cost-free living and also grows over a period of mainly or months to maturity, the latter shown by the presence of a clitellum (saddle). Earthworms room hermaphrodites (i.e. Castle act as both male and female), however most species reproduce sexually by exchange of sperm (amphimictic), whilst rather reproduce asexually (parthenogenetic). Cocoons are developed periodically by adults through secretions native the clitellum, and they space deposited in the floor (Fig. 20.1). The exact timescales and also numbers created are species specific.



CharacteristicEpigeicEndogeicAnecic
Adult sizeSmall-mediumMediumLarge
Reproductive rateHighIntermediateLow
LongevityShort-livedIntermediateLong-lived
PigmentationPredominantly red colorationPredominantly unpigmentedPredominantly brown to black coloration
MobilityHighly mobile—selected members of this team are taken into consideration pioneer speciesIntermediateLow mobility, generally uncovered in undisturbed habitats, inhabiting semipermanent burrows
Location in the soil profileOrganic horizons in or near the surface litterUsually found in the soil profile inhabiting horizontal burrows within 15 cm that the surface (in pleasant locations)Construct semipermanent upright burrows (to a depth that 2 m) in the floor profile. Burrows open up onto the soil surface
Food sourceDecomposing surface litterOrganic matter ingested through soil (geophagous)Surface litter attracted into the burrow—usually at night
Temperate examplesEisenia fetida, Dendrodrilus rubidusAporrectodea caliginosa, Aporrectodea roseaAporrectodea longa, Lumbricus terrestris
Tropical examplesPerionyx excavatus, Eudrilius eugeniaePontoscolex corethrurus, Millsonia anomalaAmynthas rodericensis, Eutyphoeus gammiei

Source: adapted from Butt and also Lowe (2011).


For the purposes of this chapter, that is an ext relevant to separate earthworms into two distinctive categories—those that inhabit organic matter (litter or compost dwelling) and those the inhabit the mineral soil (soil dwelling).


View chapterPurchase book

Tsuyoshi Kawada, in Handbook of Hormones, 2016

Receptors

Structure and also Subtypes

Genomic analysis of the annectocin receptor (AnR) gene revealed the the intron-inserted position is conserved between the AnR gene and mammalian OXT/VP gene <3>. In situ hybridization making use of an earthworm showed that the AnR gene was specifically expressed in the nephridia situated in the clitellum region <3>. Another annelid receptor homolog because that the OXT/VP suprafamily peptide to be cloned from the leech Theromyzon tessulatum <4>, back no endogenous ligand has actually been uncovered in the leech. The receptor homolog gene is express in the genital tract, ovary, and mind of the leech. Furthermore, leech AnR mRNA gradually increases throughout the duration of sexual maturation, and also disappears after egg-laying <4>.

Signal Transduction Pathway

Administration the annetocin to Xenopus oocytes express AnR root cause Ca2+-dependent signal transduction. The EC50 value of annetocin for AnR to be calculated come be approximately 40 nM by dose–response curves for existing shifts <3>.


Tarmo Timm, Patrick J. Martin, in Thorp and also Covich's Freshwater Invertebrates (Fourth Edition), 2015

Reproduction and Life History

The individual life time of tubificids and lumbriculids in aquaria frequently lasts number of years and also may include several reproduction cycles. Some people of T. Tubifex and also Spirosperma ferox have reached an age of 10 or more years. The oldest recorded age was because that an separation, personal, instance of C. Lacuum (an aquatic “earthworm”), which live 46 years in one aquarium, although there is no reproducing. The actual lifetime of the same varieties in nature is undoubtedly shorter due come predation. The facultative parthenogenetic varieties T. Tubifex have the right to survive and also reproduce in aquaria for plenty of years, even at a persistent room temperature, as have the right to the architomic clones the the tubificids Bothrioneurum and also Aulodrilus. Some other varieties can live numerous years there is no reproduction unless “hibernation” allows them to undergo the common sexual process (Timm, 1987). Most types reproduce once a year and also then reabsorb the entirety system apparatus (except gonads) and apparently become immature until the following sexual cycle. Oligochaetes space hermaphrodites, mainly protandric, v the partners trading sperm during copulation. The clitellum and some one-of-a-kind cutaneous structures, occasionally in mix with penial chaetae (Cuadrado and also Martínez-Ansemil, 2001; Caramelo and also Martinez-Ansemil, 2012), aid to organize the partner together during this process. The extraterrestrial sperm is save in spermathecae either as amorphous mass, organized right into bundles of different complexity, or together spermatozeugmata consist of of 2 kinds that spermatozoa, the last characteristic the the subfamily Tubificinae (see Jamieson and Ferraguti, 2006). Once spermathecae are absent, the spermatophores space then attached come the exterior of the partner’s body; this wake up in the tubificids Bothrioneurum and also Paranadrilus, the crassiclitellate Criodrilus, and also some others. Both the egg(s) and also alien sperm will certainly be laid into a cocoon secreted by clitellum. The mommy worm sheds the cocoon by crawling backwards, after i beg your pardon the cocoon’s covering will harden and also the ends will certainly contract into a sealed plug. Eggs are fertilized in ~ the cocoon, and breakthrough is direct. After some weeks, the young worms will certainly leave the cocoon. “Microdrile” aquatic worms place large, yolk-rich eggs. In contrast, the eggs of “megadriles” room smaller, and also embryonic expansion depends ~ above nutritious liquid secreted right into the cocoon through the mother’s clitellum. Spermatogenesis occurs earlier than oogenesis and at reasonably lower temperatures. This describes the observation that in a moderate, seasonal climate many aquatic oligochaetes mature and copulate in winter or beforehand spring and lay egg in the beginning of the warmer period.

Although oligochaetes might reproduce only as soon as per year in seasonally cool aquatic systems, some species (e.g., L. Hoffmeisteri) have the right to mature promptly in warmer water and produce number of generations every year. Some species (e.g., T. Tubifex and Ilyodrilus templetoni) can produce parthenogenetic eggs, as shown by lack of spermathecae in numerous individuals. Part rare taxa additionally lack the masculine apparatus, as in Tubifex pomoricus. Parthenogenesis is a method to stop the temperature difficulty with spermatogenesis and to develop several generations a year, together in the situation of T. Tubifex and L. Hoffmeisteri. However, fecundity slowly decreases over numerous parthenogenetic generations.

Another type of asexual reproduction that fully avoids the resource- and time-consuming sexual process and egg-laying is vegetative reproduction, either by architomy or paratomy. Architomy way enhanced capacity to regenerate a complete animal from different pieces, after one of two people a violent strike or voluntary fragmentation. Architomy is nearly obligatory in L. Variegatus yet common also in some Tubificidae (e.g., Bothrioneurum, Aulodrilus, Potamothrix bedoti) and also Enchytraeidae (Cognettia and also some others). At the very least in this tubificids, architomy is properties of warmer periods, conversely, at reduced temperatures, the procedure ceases and at least some part of the populace becomes sexually mature. In Lamprodrilus mrazeki (Lumbriculidae), architomy wake up in cysts developed in summertime when pools dry up.

A an ext advanced method of asexual reproduction is paratomy: the production of a chain the zooids by longitudinal budding. This characterizes whole families that Naididae, Pristinidae, and also Opistocystidae. Paratomy deserve to prevail throughout favorable seasons, while sexually mature individuals appear and produce cocoons mostly before a colder or drought period. The parents then commonly die after forming cocoons.


M.E. Benbow, in Encyclopedia that Inland Waters, 2009

Introduction

The phylum Annelida is stood for by five classes that freshwater worms, v the Oligochaeta, Polychaeta, and also Hirudinea being the most usual groups encountered in inland freshwater systems. The remaining classes encompass the Branchiobdellida and also the an extremely rare Archiannelida, the former practically exclusively stood for by commensals or parasites of crayfish. Lot of this synopsis of the freshwater Oligochaeta and Polychaeta is synthesized indigenous references noted in the additional Reading section.

The Annelida comprises the segmented worms, consisting of earthworms (Oligochaeta), leeches (Hirudinea), and the generally marine tubeworms (Polychaeta). The basic annelid body is a linear collection of nearly identical segments, except for the prostomium (head) that dwellings the brain, and also the pygidium, i beg your pardon is the terminal component of the body that holds the anus. Number of burrowing and also tube-dwelling polychaete taxa have actually modified components of the body the are distinct regions that segments. Annelids usage coelomic fluid pressure as a hydraulic skeleton, which works as one antagonist with longitudinal muscle in a peristaltic manner, to move the organism forward along top of and within substrata. Annelids are hermaphroditic (having both male and female reproductive organs) and also the freshwater representatives space usually syngamic (i.e., organisms v gamete fusion) v cross-fertilization; some types are recognized to reproduce by budding. The Oligochaeta and Polychaeta room morphologically distinct and easy come distinguish, yet both are typical to the depositional area of lakes, wetlands, streams, and also rivers wherein they assume a decompositional role in organic issue processing. The these 2 understudied great of freshwater annelids, the oligochaetes are better known due to the fact that they space relatively much more diverse and abundant throughout temperate zone regions of the world, if polychaetes space reported come be much more widespread throughout the tropics, with just a couple of species report from pleasant latitudes.

Oligochaeta

There space at the very least 10 households of oligochaetes that have freshwater representatives. Four households are strict aquatic and include the Aeolosomatidae, Naididae, Tubificidae, and Lumbriculidae. There space several other taxa indigenous various families that are considered amphibious or semiaquatic because of inadvertently wash-ins during flooding or various other disturbances. Although comprehensive studies are doing not have for the Oligochaeta, many taxa (e.g., Tubifex) are thought to have a cosmopolitan circulation with a couple of representatives limited to details regions the the civilization (e.g., numerous Lumbriculidae). A unique species of the Enchytraeidae (Mesenchytraeus solifugus – ice cream worms) is discovered only on the glacial ice cream sheets of the Pacific Northwest, where populaces feed almost exclusively on tree pollen and algae.

Oligochates show distinct metamerism, wherein the human body is composed of virtually identical human body segments serially aligned follow me the size of the body. The variety of segments varies by types with part taxa (e.g., Haplotaxidae) with almost 500 segments, but most taxa with usually much less than 200 (e.g., most tubificids). Aquatic oligochaetes are frequently smaller 보다 their terrestrial relatives, hardly ever reaching human body lengths greater than 30 mm. On every segment are discovered setae, small, stubborn hair-like structures that offer as outside grips for locomotion. In general, aquatic types have longer setae than do their terrestrial relatives. The setae space extended throughout longitudinal muscle contractions for motions that are helped with by peristaltic contractions of the coelomic (body cavity) fluid. The direction that the body wall surface contractions can be reversed to enable for behind locomotion. Most aquatic oligochaeta move over or in ~ the interstitial spaces the substrata, yet a couple of are well-known to be reasonable swimmers (e.g., some varieties of Naididae) that relocate in a serpentine manner immediately above the substrate.

Gas exchange takes location through the thin body wall surface in every aquatic oligochaetes; however, some tubificids and naids are known to pump water into the anus to effectively increase the body wall surface area easily accessible for gas exchange, and also other taxa have actually ciliated anal gills that offer a supplementary duty to body wall gas exchange. In addition, some species of tubificids additionally have respiratory pigments that assist in respiration. These extr respiratory mechanisms permit those taxa come survive and also occupy habitats with really low dissolved oxygen.

Although missing in all various other oligochaetes, many types of Naididae have epidermal eyespots v photosensitive receptors. The evolutionary significance of these frameworks within a solitary family the oligochaetes is tho debated, as plenty of polychaetes and also a couple of Hirudinea have comparable structures. Oligochaetes additionally possess additional sensory structures that are well-known to aid in tactile, thermal, and also chemical detection.

Oligochaeta are typically hermaphroditic and most have sexual reproduction that involves reciprocal sperm transfer and fertilization the takes place in a cocoon that is secreted through the clitellum; however, numerous taxa that the Naididae and also Aeolosomatidae give birth asexually via budding. The clitellum is a reproductive component of the oligochaete body consisting of collection adjacent segments wherein the epidermis is swollen and also house glands that secrete mucus because that copulation. In many sexually reproducing aquatic taxa, the clitellum is just two segments wide and sometimes only one cabinet thick making the difficult, if not impossible, come detect through the naked eye. For some terrestrial taxa the clitellum can be as great as 60 segments vast and countless cells thick, providing it a ‘girdle’ appearance. The mucus from the clitellum develops a chiton-like cocoon framework where fertilization and also embryonic advancement occurs. This cocoon is believed to pat a duty in desiccation resistance and dispersal capability of aquatic oligochaeta.

Aquatic oligochaetes accounting the depositional habitats of many aquatic habitats, functioning as decomposers that decaying organic matter and mixing and aerating the benthic substrates with burrowing. Density of aquatic oligochaete is typically low in streams, but can it is in appreciably high in eutrophic habitats v low liquified oxygen or anoxic conditions. Indeed, aquatic oligochaetes space often considered indicators that nutrient-enriched flow waters when in fairly high abundance compared with various other benthic invertebrate taxa. Many aquatic oligochaetes have the right to withstand lengthy periods the time under anoxic, or close to anoxic, conditions. Due to the fact that of this, oligochaetes are often most abundant in wetlands and also marshes and also can achieve large benthic densities in the deep area of lakes. Because that instance, populaces of some tubificid worms can attain densities as great as 8000 people per square meter. However, there have actually not been extensive studies regarded the ecology of specific aquatic oligochaetes beyond vast taxonomic surveys or research studies where oligochaetes were gathered as part of much more general benthic invertebrate research.

Polychaeta

Of 85 households in the course Polychaeta, just 10 have representatives in brackish and also freshwater habitats. Over there are an ext than 5000 identified types in this class, with less than 2% classified together euryhaline or freshwater and also less 보다 50 species minimal to freshwaters. Most freshwater and euryhaline representatives room within the Nereididae (Figures 1 and also 2), i m sorry is mainly a naval family. However, there are other family members containing a few euryhaline and also freshwater types (i.e., Phyllodocidae, Nephtyidae, Spionidae, Sabellidae, Serpulidae, and Ampharetidae). Over fifty percent of the 50 euryhaline and also freshwater types of Nereididae are located in the tropical and subtropical west Pacific region, while only 10 species are uncovered in phibìc America. Freshwater and also euryhaline polychaeta have actually been report from phibìc America, including Alaska, California, Georgia, the great Lakes, new York, caves of Mexico, and also the Philippines, Canada, Papua brand-new Guinea, Fiji, brand-new Zealand, the Amazon, Japan, China, India, and also Hawaii, and probably other regions that the world. Many freshwater or brackish polychaete habitats were once geographically associated or are presently associated to the ocean. In addition, many specimens have been built up within around 30 km of the ocean, sustaining a concept of recent evolution into freshwater. Interestingly, it has been reported that some freshwater taxa show direct advance rather than the more usual larval advancement of marine representatives, a feature similar to the freshwater relatives of a few other predominately maritime invertebrates (e.g., crabs, shrimps, bivalves).


*

*

The general polychaete body setup is distinct from oligochaetes in that each segment is characterized by two lateral muscular appendage-like structures referred to as parapodia (Figures 1 and 2). Every parapodium includes setae (usually multiple) that are supplied in locomotion the can occur along the surface of substrates, within the interstitial spaces the substrates, or because that swimming, while some are advanced for a tube-dwelling existence; however, this last life style is no common among the freshwater forms. Many polychaetes have a highly arisen prostomium that contains sensory guts that incorporate antennae and also eyespots (Figure 2). Numerous of the nereid taxa have actually pharyngeal jaw-like structures, located several segment posterior that the prostomium, that are provided for capturing prey or shredding detritus (they can also leave a nasty bite if provoked while handling).

Very tiny is known about the ecology of freshwater polychaetes. The varieties that have been studied many are the Nereididae, and are many often gathered from extremely organic depositional habitats that streams, wetlands (and rice paddies), and also lakes. A few species have been recorded to have an arboreal visibility in phytotelmata (e.g., small collections that rainwater linked with plant leaf axils or in bromeliads), but small is known around their ecology. Like their oligochaete relatives, polychaetes appear to be rather tolerant to low dissolved oxygen conditions. The Namalycastis species often have a hemoglobin sinus that runs the size of the body, and also it is presume to add to respiration in anoxic problems of depositional habitats (Figures 1 and also 2). In tropical regions of the world, freshwater polychaetes are regularly abundant in the heavily polluted will of streams and also rivers, possibly making them bioindicators that anthropogenic nutrient enrichment. The benthic polychaete taxa room thought to be scavengers and also detritovores; however, that is most likely that some nereid develops are active predators together well. Many freshwater polychaetes room thought come ingest any and all debris, assimilating the linked microbial flora and organic matter, and they might play a notable function in decomposition in slow flowing tropical streams. Very little is well-known of the reproductive methods of freshwater polychaetes, but most literature says that they have the right to reproduce sexually or asexually, and also then go with direct advancement with no larval stage.

One that the relatively more well-documented nonnereid types of freshwater polychaete is Manayunkia speciosa (Sabellidae) that has actually been report from numerous locations in north America, consisting of the good Lakes region, brand-new Jersey, Georgia, new York, California, Alaska, north Carolina, and also South Carolina. This types is generally less than 5 mm in body length and also secretes rubber to type a mud/silt/sand tube in i m sorry it lives in a filter-feeding fashion, using ciliated tentacles of the prostomium. In temperate areas of the world, this is most likely the many common species collected by benthic ecologists.


Annelids blee both sexually and also asexually. Sex-related reproduction is many common amongst all main family members of Oligochaeta and Hirudinea. Throughout copulation, 2 mature, hermaphroditic animals adopt in such a way that their heads face opposite directions. In this position the masculine genital pores space opposite to the spermathecal opening of the various other (Figure 20.8). Copulatory structures, modified musculature the the body and genital chaetae, aid in the exchange of spermatozoa. In part families, accessory glands create a secretion that ‘glues’ partners together. Copulation last around 5–10 min. The spermatozoa room stored in the spermatheca until the cocoons are laid. Cocoons are formed by a clitellar gland secretion produced in the clitellum the acts as cocoon membrane. The membrane originally is elastic and also transparent. By contractions the the body wall surface musculature, the membrane slides towards the head. Once passing the female genital pore, the eggs room pushed into it; and also when passing the spermathecal opening, the spermatozoa space added. The fully formed cocoon is deposit in the upper layer the the substrate or enclosed to hard material, prefer macrophytes. ~ the cocoon is deposited, that hardens once the membrane becomes chitinous and takes a distinctive shape. Cocoons can include up to 40 eggs. The cocoons room deposited a considerable time period after copulation due to the fact that the mrs reproductive device takes longer to develop. Cross-fertilization is usual in annelids, however self-fertilization may additionally occur. The time of sex-related reproduction varies widely amongst annelid species in an answer to different environmental conditions. Some develop cocoons transparent the year, whereas rather are minimal to specific weeks.



In naidids, asexual reproduction (mostly through paratomy) is considered the leading type, while sex-related reproduction occurs rarely and then just sporadically. Beforehand in the twentieth century, Piguet (1906) observed that sexual reproduction the some types occurred seasonally in particular sites. Come survive durations of unfavorable conditions, specifically droughts, safety cocoons enable populations to stand up to stress and also recover when favorable environmental conditions return. The cocoon is an efficient trait adaptation to endure adverse conditions. In this regard, the cocoons of naidids in too much habitats room analogous to the gemmules of sponges, the resting eggs of rotifers, and the ephippia that cladocerans (Parish, 1981). Christensen (1984) confirmed that a good variety of asexual reproductive settings are known among aquatic oligochaetes. He identified four main species of asexual modes and indicated the genetic and also ecological implications, as follows. First, the frequently expressed expectations of a strong predominance of one specifically adaptive genotype space not born out. Second, in most cases, a number of genetically distinct clones are existing in each population, and they present a strong differential circulation in heterogeneous environments, denote an efficient exploitation of the obtainable resources. Third, most situations of asexual propagation room reproductive tactics of your own and not escape mechanisms. And finally, the mechanisms basic asexual propagation are facility and indicate many elements of the life history.

The ability of tubificids come reproduce parthenogenetically following, or in place of, bisexual reproduction has been displayed (Poddubnaya, 1984). Throughout parthenogenesis, the spermatogenesis ceases at an early stage of sexual cell development. Along with some peculiarities that the framework of the sexual system, this rules out the opportunity of self-fertilization in this family of worms.


Nikolai J. Tatarnic, in recommendation Module in Life Sciences, 2018

Male-Male Competition

The development of copulatory wounding as a viable adjustment strategy is partly described as an outcome of competition amongst males, together they vie come fertilize as numerous female eggs together they can, to the exclusion of their competitors. In the p weevil Callosobruchus maculatus copulatory wounds inflicted by spines on the masculine genitalia damage the mrs genital tract (TP) (Crudgington and Siva-Jothy, 2000) to reduce female lifetime reproductive success (Rönn and also Hotzy, 2012). Males with longer spines attain greater mating success in sperm compete (Hotzy and also Arnqvist, 2009; Hotzy et al., 2012). Interestingly, fairly than reducing woman willingness to mate, genital damage apparently leader to the opposite, with females remating sooner and laying under eggs, possibly limiting the services to males. Wounding per se may therefore be a pleitropic by-product of choice on other reproductive characteristics that boost male fitness (Morrow et al., 2003). In the simultaneous hermaphroditic earthworm Lumbricus terrestris, wounds brought about by copulatory setae situated ventrally ~ above the body, away from the clitellum (the worm’s reproductive organ), enable for the transfer of secretions that induce increased sperm uptake (TST) (Koene et al., 2005). Note that in both examples wounding is not under straight selection: in the first it is likely a pleitropic side-effect, and also in the 2nd the wounds are simply a mechanism by which antagonistic secretions space transferred.

Evidence for the underlying duty of sperm vain in control TI in some systems can be found in the mating system of the traumatically inseminating spider Harpactea sadistica (Řezáč, 2009). In most spiders, males inseminate the female v her epigynum (genital opening), and the sperm climate pass into her spermatheca, a sperm storage body organ with a single opening. As is usual in many arthropods, fertilization occurs just before oviposition: the eggs descend right into the uterus, where sperm is then released native the spermatheca, and also the mrs lays freshly fertilized, single-celled eggs. Whereby females own a cul-de-sac type spermatheca with one opening, either the sperm the the last masculine to mate with the woman are offered first, as they reside closest come the spermathecal opening, or rather the sperm native multiple matings i do not care mixed, rendering paternity unpredictable. In H. Sadistica, TI permits the masculine sperm come bypass the spermatheca (which is atrophied in this species), and also instead travel straight to the ovaries whereby fertilization occurs, with females eventually laying partially developed embryos. In this circumstances TI is believed to enable males come “escape” sperm vain by alternate the typical order the sperm precedence (Řezáč, 2009). In traumatically inseminating Cimicomorpha (bed bugs and their allies), fertilization likewise occurs in the ovaries, before ovulation. However, ovarian fertilization wake up in several other cimicomorphan lineages also (e.g., the family members Miridae (Wheeler, 2001), which contains a single TI genus, and the Tingidae (Marchini et al., 2010), which have actually no recognized TI species), indicating that ovarian fertilization have the right to be achieved without TI, and also thus may not be an end result of TI in the Heteroptera. It is clear the there is much to learn about reproduction in this taxa prior to we deserve to draw any firm conclusions top top the relationship between TI, sperm storage, and also fertilization.


1.

Laboratory name and address:

Laboratorio de Ecologia de Agroquímicos, Instituto Biológico, São Paulo SP, Brazil

2.

Contact persons:

3.

Title the the analysis method:

Estimation of the bioaccumulation factor of radiolabeled pollutants in compost worms Eisenia andrei/fetida

4.

Principle:

As earthworms are an integral component of plenty of soil food webs, they might serve as bioindicators because that the potential perils posed by pollutants (pesticides, drugs, and also metals) to floor biota. The an approach presented is a laboratory bioassay to advice the bioaccumulation of radiolabeled (using a 14C-label) pollutants in compost worms that prosper in soil and incorporate a particular amount the radiolabeled pollutant. Liquid scintillation counting is provided to calculation the quantity of radioactivity present in organic extracts all set from compost worms and also soil.

5.

Scope:

The current an approach is applicable to the determination of radiolabeled pollutants in soil making use of earthworms as soil bioindicator organisms.

6.

Equipment and also instruments:•Liquid scintillation counter (LSC)

Laboratory microwave

Rotary evaporator

Freezer

Homogenizer

7.

Reagents and materials:•Organic solvents, residue evaluation grade

14C-labeled target pollutant

Pollutant (nonlabeled)

Adult Eisenia andrei earthworms

8.

Detailed procedure (protocol):•One week prior to the start of the study, sweet 200 g samples of various soils in 500 mL glass beakers and moisten to 60% of the preferably water holding volume (MWHC) through deionized water, together recommended by OECD overview Nº 317.

Weigh enough sample replicates to have at the very least three floor replicates because that the treatment with the pollutant and also three replicates because that the control.

For acclimation to laboratory problems at the very least 1 day prior to the start of the study, place 5 adult earthworms every replicate every weighing an ext than 300 mg with clitellum in untreated soil with at the very least 50 g floor per earthworm.

On day 1 that the study, slowly treat and also mix the soils through a equipment of 14C-target pollutant. The samples stay in a fume hood till the solvent has actually evaporated.

Only after the solvent has evaporated native the floor the acclimatized adult earthworms are placed in the cure or manage soil.

Cover the surface of the glass beakers v perforated plastic movie to enable air exchange.

Weigh each finish glass maker containing the moistened soil and also the compost worms to evaluate the dynamics of water evaporation during the study period (Vampré et al., 2010).

Keep the glass beakers in ~ a constant controlled temperature (e.g., 25°C) and standardized light periods (e.g., 12 h).

Every 3 days sweet the beakers and readjust the water contents to store the soil moisture in ~ 60% MWHC.

After 14 days, disassemble the beakers and also separate the worms; wash in insanity water, dried in filter paper and weigh to compare v the early stage weight and determine the impact of the pollutant on development of the organisms.

Maintain the earthworms at 4°C for 24 h top top wet filter paper, which is readjusted after two durations of 12 h to allow emptying of floor or substrate particles from your guts. Freeze for 24 h. Follow the extraction an approach by Papini et al. (2006) to recoup the pollutants native the necessary extracts all set from compost worms and also soil. Every organisms of each replicate room extracted with each other by this method.

9.

Calculations:

The bioaccumulation variable is established by splitting the amount of pollutant present in the earthworms (Co, in kBq/g or µCi/g) by the quantity in the floor (Cs, in kBq/g of floor dry weight):
BAF=CoCs

10.

Quality control:

Preliminary experiments should be performed to determine the extraction recovery that the target pollutant from the soil and earthworm tissue. The recovery must be at the very least 85% for the included 14C-labeled target pollutant.

To estimate the extraction recovery indigenous earthworms, wash five adult worms (with clitellum and more than 300 mg each) in madness water in a plastic sieve, dry carefully in filter record and freeze in ~ −18°C for 24 h. Spike the frozen animals with a equipment containing a mixture that the 14C-pollutant and also a reasonable—but no lethal—amount that the pollutant. Reduced the animals into tiny pieces of around 1 cm and also homogenize for about 15 min under a fume hood to allow evaporation the the spiking solvent.

Material indigenous the treated earthworms is extract by addition of a solvent or a solvent mixture by microwave-assisted exploit (MASE) utilizing frequent quick (a couple of seconds) low energy cycles together the earthworms save a significant amount of water. The heating into microwave is intercalated by temperature decrease v immersion in ice-bath (method by Andréa et al., 2001). Depending on the solvent used, few mL aliquots of the extract acquired are straight counted through LSC using a scintillation cocktail. If the solvent is a quencher, it deserve to be rotary-evaporated and resuspended in another an ideal solvent compatible with liquid scintillation counting.

To estimate the recovery complying with extraction native soil, an adequate soil extraction method should it is in established. Because that example, the samples might be extract by MASE in miscellaneous cycles of couple of seconds and low level the microwave energy, additionally intercalated through ice-bath. The extraction recovery have to be developed in triplicates utilizing 3.0 g wet samples spiked through a recognized amount the the pollutant.

Extraction recovery is calculated together the ratio between the lot of 14C-pollutant recovered in soil and also earthworm extracts, and also the lot of 14C-pollutant added into the samples, taking right into account the dilution factors.

11.

Remarks:

For a test to it is in valid, the mortality of the bioindicator organism need to not exceed 10% the the total variety of earthworms in each replicate of control or cure samples.

Ensure that the measurement conditions of the LSC room checked to enable valid measurements. These encompass daily checks of the carbon-14 calibration standard and the typical of elevator radiation come verify the performance of counting.

12.

Interferences, troubleshooting, and also safety:

All activities personnel should be trained top top the safety and also correct managing of the pollutants, radiation materials and also the quenchers because that LSC.

13.

References:

Andréa, M.M., Papini, S., Nakagawa, L.E., 2001. Optimizing microwave-assisted solvent exploit (MASE) of pesticide from soil. J. Environ. Sci. Health. Component B, Pesticides, Food Cont. Agric. Wastes, B 36, 87–93.

OECD – (Organization for financial Co-operation and also Development), 2010. OECD guideline Nº 317. Bioaccumulation in Terrestrial Oligochaetes. 30 pp.

Papini, S., Langenbach, T., Luchini, L.C., Andréa, M.M., 2006. 14C-Paraquat in compost worms Eisenia foetida. J. Environ. Sci. Health. Component B, Pesticides, Food Cont. Agric. Wastes, B 41, 523–530.

Vampré, T.M., Fuccillo, R., Andréa, M.M., 2010. Oligoqueta Eisenia andrei como bioindicador de contaminação de solo por hexaclorobenzeno. R. Bras. Ci. Solo 34, 59–66.

14.

Minimum technique validation data:


The an approach validation was conducted using 14C-Paraquat and 14C-Simazine herbicides (Tables 3.36 and 3.37).


Table 3.36. Radiocarbon recoveries from 5 (five) earthworms spiked through 14C-herbicides using different methods


MethodSolventVolume (mL)ExtractionConditionsRecovery (%±SD)
1Ethyl acetate100Shaker4 cycles, 6 h each100.2±2
2Methanol150Shaker5 cycles, 6 h each88.9±2
3Methanol150Soxhlet1 cycle, 8 h116.8±5
4Methanol:dichloromethane (10:5)15Microwave15 cycles, 30 s each and also 1120W99.2±8

MethodSolventVolume (mL)ExtractionConditionsRecovery (% ± SD)
1Methanol100Shaker3 cycles, 8 h each97.1±2
2Methanol100Soxhlet1 cycle, 12 h105.1±2
3Water:methanol:dichloromethane (1:8:6)15Microwave10 cycles, 20 s each and 800W89.4±1
4Hexane:Acetone (75:25)15Microwave12 cycles. 2 min each and also 480W81. 1±1

The percentage full radiocarbon recovery together 14C-extractable + 14C-bound in soil and earthworms at the finish of the experiment was: 93.9±9%.

The range of sports on the performance of the biological combustion method to identify the 14C-bound in soil and also earthworms to be 91%–95%.

The border of Detection (LOD) was calculated together the median + 3 times of the activity (dpm) typical deviation the the blanks (6:4 that monoethanolamine and also scintillation cocktail), approximated as 285 dpm (4.8 Bq).

See more: What Book Has The Most Ar Points ? Reading Confidence And A Record

The limit of Quantification (LOQ) was identified as the typical + 10 times of the activity (dpm) typical deviation of the blanks, approximated as 593.0 dpm (9.9 Bq).