Clitellum Segment



5); length approximately 400µ, thickness 20µ. There are two sets of muscles in each segment: a ring of circular muscles that can constrict or narrow the segment, and longitudinal muscles that can shorten the body. Look for the worm’s setae, which are the minute bristle-like spines located on every segment except the first and last one. The clitellum is a structure on the anterior portion of the worm that generates mucus to aid in sperm transfer from one worm to another; it also forms a cocoon within which fertilization occurs. Each worm then exudes a mass of slime which encloses, or forms a connection between, the bodies of both worms from segment 9 to the end of each clitellum at segment 37. Discover Life's page about the biology, natural history, ecology, identification and distribution of Discover Life. Phylum:Nematoda Heartworms Unsegmented Body enclosed by cuticle First Complete. Spermathecae intramuscular, around ab, 4-8 on each side in 14/15, 15/16. allochthonous Amynthas Aporrectodea caliginosa Beddard blood vessel Body cylindrical body wall Bouche British records calciferous glands caudal region clitellum Clitellum extends coelomic coelomic fluid colour copulation Dendrobaena diameter diapause Distribution dorsal pore duct earthworms egg capsule Eisenia fetida Enterion extends over. One can count the position of organs or pores by using the mouth or clitellum as the reference starting points. ' 'The two species display similar body length and segment number as well as show resemblance in the shape of the clitellum and tubercula pubertatis. Segments each contain elements of such body systems as circulatory, nervous, and excretory tracts. This phylum is split into 3 classes, the largest of which is the Polychaeta (many hairs) to which most of the segmented worms in the ocean belong. Segments The body is segmented and each segment is separated from its neighbors by a distinct circumferential groove. o Ovaries – 1 pair, ventral surface on segment 13 o Oviducts – 1 pair, in segment 13 opens to genetal pore on segment 14 o Seminal receptacles – In segments 9 and 10 o Reproduction occurs when: § 2 worms come together at clitellum § When eggs leave ovaries, clitellum secretes mucus tub on anterior segments to pickup eggs and sperm. The integumentary nephridia are found scattered on the inner side of skin or body wall in all segment except first three segments. Spiracle openings in each segment #11. All segments of body except the first, last and clitellum have chitinous setae embedded in each segment. Flap covering mouth that senses light/dark, food. Clitellum is annular and setae are retained. A small, fleshy lobe, the prostomium (Fig. Das Clitellum besteht bei den Crassiclitellata aus mehreren Zellschichten und ist somit dicker (lat. liatsmontessori. Ventral nerve cord runs from brain along length of body, swelling in each segment to form ganglion movement Have circular and longitudinal muscles that function as part of hydrostatic skeleton. They should be located at about segment 15. A temporary clitellum is formed during breeding season. Setae are absent in the first segment, clitellum and last segment. How do earthworms eat and poop — and other surprising facts Earthworms have groups of bristles on each segment of the body that move in and out to grip surfaces as they stretch and contract. 1J, T), and they were divided into three groups, each group has twenty worms. Earthworms lay eggs inside amber-colored cocoons their bodies produce. The fertilized eggs are deposited in a cocoon, secreted by the clitellum; the cocoon is buried in mud or affixed to submerged objects. In order for the earthworm to live on, the anterior end segment must be long enough to contain the clitellum and at least 10 segments beyond it. Internal Anatomy earthworm in a dissecting pan. Internal Anatomy. On mature earthworms, you will find a saddle or glandular ring called a clitellum. In all our specimens the clitellum is very apparent, extending from segment 13 (14) to 19; it is distinguished from the remaining part of the body as well by its darker colour, as by the pronounced glandular integument of its segments. Green Mouth Clitellum Segment Sperm groove Setae Anterior end Sperm duct opening Figure. each segment of an annelid. Refer again to the diagram of the ventral view of the worm to locate and identify the external parts of its reproductive system. Male pores on 17th segment, on tubercules (penises) extending more laterally than medially. The clitellum (= cingulum), a prominent circular band of glandular nature, is found from the 14th to 16th segments. Excretory system of Earthworm The process of removal of metabolic waste products including nitrogenous material like ammonia, urea, uric acid, amino acid, etc. Length of living specimens can be 600–800 mm. XVIII, a cylindrical body with perichaetine setae, caeca on segment XXVII, copulatory pouches without diverticula and stalked glands, bithecal spermatheca with nephridia, and the first spermathecal pore on segment 4/5. In each segment, there are 200-250 nephridia but in clitellum 10 times more is found. How many setae are there on each segment and how are they arranged? _____ The clitellum (segment 33-37) is a swelling of the body found in sexually mature worms and is active in the formation of a mucus. it is not considered to be a segment of the worm. If an earthworm is split in two, it will not become two new worms. The clitellum is the place where the fertilization actually takes place. This banner text can have markup. The clitellum is a structure on the anterior portion of the worm that generates mucus to aid in sperm transfer from one worm to another; it also forms a cocoon within which fertilization occurs. , segments 14-16. The male pores are located in segment 15 which is one segment behind the one that contains the female pores. As a rule - to which, however, there are exceptions - the clitellum consists of two cr three segments only in the small aquatic Oligochaeta, while in the terrestrial forms it is as a general rule, to which again there are exceptions, a more extensive, sometimes much more extensive, region. Anus: end of the digestive tract. Reproductive readiness is evident by the swollen clitellum, an enlarged region seen partway down the length of the body from segments, or metameres, 31 or 32 to 37. The other two species usually do not have male pores (Fig 1A, 3A- C). Peristomium The first body segment is called the peristomium. In front of peristomium there is a lobe like sensitive structure called prostomium. Earthworm, Lumbricus sp. Which end of the worm is pointier than the other end? Anterior 3. This arrangement lines up the clitellum of one worm with the genital segments of the other worm. In mature worms 14-16 prominent dark band of glandular tissues called clitellum is present. In the three segments between the spermathecal and clitellar regions the nephridia are relatively sparse and arranged in a line across the middle of the segment; they appear to be more robust than those behind the clitellum. The first group of the two earthworm species was amputated at Pre-clitellum (10 th segment) and the second group of the worms were amputated at the clitellum (15 th segment). Earthworms are in the class Oligochaeta (few hairs), and the leeches belong to the class Hirudinea. diverticulum 3. Locate the clitellum, which extends from segment 33 to segment 37. Clitellum of each worm opposite segments 9 to 15 of other. terrestris). Segment: one of the rings of an earthworm. EXPERIMENT. Eggs hatch inside the cocoon, and the cocoon itself becomes a protective egg for the baby worms inside. When I am a few weeks old you will notice a light-colored band forming near my front end. It is located about. Besondere ventrale oder laterale Differenzierungen des Clitellums werden je nach ihrer Form als Pubertätstuberkel, Pubertätsleisten oder Pubertätswälle bezeichnet. Usually there are 120 true somites. Acknowledgement: Ross Gray. it is not considered to be a segment of the worm. Segment mehrere. Using the segment partitions on the diagram, let's see what makes up our compost friend. This end of the worm is usually more pointed than the posterior end of the animal. In the abdomen, the first five segments each have a pair of swimmerets, which create water currents and function in reproduction. Spiracle openings in each segment #11. The clitellum, which was not fully developed in the type, covers segments (13) 14–18 (19)—that is, the dorsal surface of either or both the 13th and 19th may be glandular, but the segments are separated by a furrow from the rest of the organ. When an earthworm has mated, the clitellum will secrete a sack of eggs. Clypeus: a shield-like plate on the face of insects and other arthropods that normally connects the labrum (upper lip) to the head. Each segment has a number of bristly hairs attached to it, which helps the earthworm to move around. PHYLUM: annelidia. clitellum compost segment. Each segment is marked externally by something called an Annuli. It is on the far anterior end of the worm. The clitellum is a reproductive structure that generates mucus that aids in sperm transfer and gives rise to a cocoon within which fertilization occurs; it appears as a fused band in the anterior third of the animal. the most posterior (last) segment contains the: anus: The glandular segments between segments 31 and 37 which must be present in order for reproduction occurs and where the cocoon material is secreted. The clitellum divides the body of the worm into 3 regions. dorsal side of the clitellum at segment 33. Segments 14-16 form a girdle-like thick band of glandular tissue called clitellum that secretes mucus, albumen and cocoon inside which eggs are laid. Sometimes, if you run your fingers on the underside (ventral) of the earthworm, you can feel the setae. The perichaetin condition is not seen in Australian acanthodriles. In this way the clitellum segments of each animal are opposite the segments containing the sexual organs of the other. Tiny excretory pores from the nephridia can be found on the lateral or ventral surfaces of all segments except those at the ends. Earthworms are in the class Oligochaeta (few hairs), and the leeches belong to the class Hirudinea. The oviduct opens on the 30th segment and the average earthworm has 100 segments. What one customer said about the earthworm dissection guide: Good first dissection. Worm Nomenclature - Book #gardeningforkidspreschool See more. Bei den Hirudinea, bei denen das Clitellum nur zur Zeit der Eiablage deutlich zu erkennen ist, umfaßt es die Segmente 9–11. The gonopores (reproductive openings) are on adjacent segments just in front of an obvious swollen area called the clitellum. Identify the anterior (head) and posterior ends. The new posterior segments will grow to be smaller in diameter and sometimes slightly different in color than the original earthworm was. Mouth: entrance to the digestive tract. Some Australian native earthworms grow to an enormous size. The clitellum is not clearly demarcated from the other segments of the body apart from a slight difference in colour. clitellum begins on segment 24, or 25, or 26, and ends on segment 30. After the eggs mature, a mucous tube secreted by the clitellum slides along the body as the worm moves backwards. Medical Definition of Esophagus. Zoology 250 Phylogenetic Trees (2017) nephridia with nephrostome opening in segment anterior to nephridiopore m) trochophore larva** clitellum (produces the. Enchytraeids (when they are adult) possess clitellum on/around segment 12, lumbricids have longer clitellum and positioned more tailward (from segment 20 or more back). Colour dark nut-brown on dorsum, paler on ventrum. jpg Author: amschaner Created Date: 3/6/2006 11:40:16 AM. bis zum 130. Now, the each worm's clitellum also produces a slime tube. Which part of the worm creates the material that forms earthworm cocoons? Clitellum 4. In summary, a reader asked us when earthworms die. The molluscs include a number of familiar animals, including snails, oysters, clams, octopuses and squids. There may be more than 100 segments in an adult worm. Lage sowie Ausdehnung der Gürtelregion sind wichtige Merkmale für die Unterscheidung der Arten. Segmenter i sin midt indeholder kønsorganer , fem par af hjerte-lignende strukturer og blodkar. This end of the body may be more flattened. Phylum Annelida Textbook Material at University Of British Columbia - Okanagan - StudyBlue. It is called boring part so it bores in soil. V koži majú veľa pigmentu, sú väčšinou tmavo sfarbené. Its clitellum is five-eighths of an inch long. A simplified key to common genera of terrestrial earthworms I. The end farther from an earthworm's clitellum is the animal's. Der Oesophagus bildet im 5. The clitellum means the earthworm is an adult and is ready to mate and lay eggs. Look for the worm's setae, which are the minute bristle-like spines located on every segment except the first and last one. The clitellum is formed by a modification of several segments, and either includes the female gonopores or is located just behind them. Studyres contains millions of educational documents, questions and answers, notes about the course, tutoring questions, cards and course recommendations that will help you learn and learn. RESULTS The NMDS (and also the CA) resulted in four well differentiated groupings of the specimens which are geographically separated as well (Figs 1–2). A simplified key to common genera of terrestrial earthworms 1. Ventral view of anterior body with clitellum. The ends of these tube structures extend through the outside skin of the earthworm. Each segment of a worm has small pairs of bristles called. It is about three-eighths of an inch wide with a circumference of 1 5/16 inches. (credit: Rob Hille). The sperm may be stored on segments 9 and 10, but the eggs are located on segment 14! Later, the clitellum will produce another wad of mucus, but this slime contains albumin (like the stuff that makes up egg whites). Eggs are produced in the. A mature worm may be 20 to 30 cm in length and possesses about 150 segments. The worms now secrete tremendous amounts of mucus, until each is enclosed in a slime tube extending from segment 9 to the rear end of the clitellum at segment 37. However setae (chatae) are absent in first , last , and clitellar region. Openings to the oviducts are found at segment 14, counting from the anterior end. The earthworm is specially adapted for feeding. When eggs are made, they are stored in the oviduct. Each body segment has a pair of locomotory organs called parapodia that bear many bristles called chetae, because of which polychaetes are sometimes referred to as bristle worms. ely: first segment of the clitellum, last segment of the clitellum, first segment of the tubercles, last segment of the tubercles, number of spermathecae and total segment number. Standard Note: Earthworm. The Night Crawler (Lumbricus terrestris) is a large worm, measuring up to 25 cm in length and up to 1 cm in diameter. Coxa: the first segment of the leg, joining the leg to the body. Locate the clitellum on your earthworm and compare it to other worms. Usually there are 120 true somites. There is another pair of male genital pores on about segment 26. Look for the worm's setae, which are the minute bristle-like spines located on every segment except the first and last one. OPENINGS TO OVIDUCTS (segment 14) SPERM DUCT OPENINGS (segment 15 & segment 26) OPENINGS FOR SEMINAL RECEPTACLES (segments 9-11) SPERM GROOVE runs from CLITELLUM to pores on segment 15. Leeches have 32 segments regardless of their age. Locate the clitellum, which extends from segment 33 to segment 37. The anus is on the dorsal surface just in front of the posterior sucker. Spermatheca. About one-third of the way back from the mouth region is a thick cylindrical collar - the clitellum. Find the pair of sperm grooves that extend from the clitellum to about segment 15, where one pair of male genital pores is located. Oviducts - Where the eggs are stored. The aortic arch is the portion of the main artery that bends between the ascending and descending aorta. Turn the worm dorsal side up. There are around 8,000 species of clitellatas. That is, they have relatively few setae per body segment. The first body segment is called the peristonium; it contains the mouth. In most annelids, each segment carries a number of bristles, called chaetae, which help in locomotion. Identify the clitellum. darnleiensis were the presence of an annular clitellum on segment XIV-XVI,. Seta b of segment number IX C. This is my clitellum. Theseg-ments of the caudal region are short, closely pressed toge-ther, with a prominent ridge of setae, giving to this portion of the body a somewhatserrated appearance. The clitellum then secretes the cocoon inside this mucus tube. Clitellum 26,27,28–40,41,42,44 involving fourteen to eighteen or nineteen segments. terrestris). Where are sclerites present in Cockroach? How many times do nymphs moult to reach the adult form of cockroach? Identify the sex of a frog in which sound producing vocal sacs are present. De huidlaag wordt de epidermis genoemd, aan de buitenkant zit een eencellige laag van epidermiscellen, waarin enkele kliercellen - en zintuigcellen voorkomen. This swollen area constitutes the clitellum, a glandular segment that secretes the cocoons or egg cases. 'A histological examination of the clitellum revealed that damage occurred to both male and female gonads. External Anatomy: Clitellum Note the swelling of the earthworm near its anterior side. Maximum width at clitellum 10–14 mm. Earthworms reproduce by forming a small egg sac – called a cocoon – at the clitellum. These female pores release the eggs. Report any cuts to your teacher. Segment: one of the rings of an earthworm. Observations. A prominent dark band of glandular tissue called clitellum covers the segments 14-16 in a mature worm. Prostomium - It covers the mouth and is used to dig through the soil. Locate the clitellum of a mature earthworm. Earthworm parts and functions Matching exercise. HABITAT: Endogeic (Soil Dwellers) -Prefer top 6 to 12 inches of soil. Pair of kidneys each segment Gas X -change through skin Hermaph rodite Segments increase body size. Near the anterior end is a segment of the worm called the clitellum, which extends from segment 33 to segment 37. There are around 8,000 species of clitellatas. Unlike the polychaetes, the oligochaetes are characterized by having a clitellum for reproduction and suction for feeding. The ganglia within each segment function to coordinate muscle contractions. Use a hand lens to observe all parts of the worm. each organism has BOTH MALE AND FEMALE sex organs, but they DON”T FERTILIZE THEMSELVES. Evolutionary Significance of Metamerism Note: Clark's 1964 scenario for explaining the coelom and segmentation related to burrowing efficiency is very popular but has major problems and has been increasingly criticized in recent years. Where is the Clitellum located on the worm? What is its purpose? between segments 32-37; used in reproduction and is close to the antirior end of te body. In addition, other characters found on P. When an earthworm has mated, the clitellum will secrete a sack of eggs. THE SCLERITES OF A THORACIC segment The parts of the thorax most generally " 5. Erst nach einigen Tagen bildet der Regenwurm mit den Drüsenzellen der Gürtelzone eine Art Kokon aus Schleim, der durch die Bewegung des Regenwurms über den Körper wandert. Clitellum commencing in front of the 15th segment (not found in the British Isles) 2 - Clitellum commencing after the 15th segment 2. Locate the clitellum, which extends from segment 33 to segment 37. The first segment of the body contains the mouth and is called peristomium (buccal cavity). The clitellum eventually slides off and is a cocoon for the new worms. Locate the clitellum, which extends from segment 33 to segment 37. Leddmakk har eit lukka blodkarsystem med to hovudårer som går langs ryggen og buken langs heile kroppen. Das Clitellum besteht bei den Crassiclitellata aus mehreren Zellschichten und ist somit dicker (lat. The ventral nerve cord has branches which lead to lateral nerves and ganglia in each segment. The last segment or pygidium, bears the anus. The present known distribution ofeach species in the. In order for the earthworm to live on, the anterior end segment must be long enough to contain the clitellum and at least 10 segments beyond it. Setae are absent in the first segment, clitellum and last segment. The shape and number of segments making up the clitellum are mostly uniform within species and are very useful diagnostic features. Each segment has it Get solutions. Look also for one pair of female genital pores on segment 14. The prostomium is located above the mouth, and is not a true segment. The arrows point to the earthworm's clitellum, an organ responsible for mucus production during reproduction. Locate the thickening of the earthworm's body at about segment 30. This phylum is split into 3 classes, the largest of which is the Polychaeta (many hairs) to which most of the segmented worms in the ocean belong. diverticulum 3. The segments are separated inside the worm by thin body walls. The gonopores (reproductive openings) are on adjacent segments just in front of an obvious swollen area called the clitellum. How do earthworms eat and poop — and other surprising facts Earthworms have groups of bristles on each segment of the body that move in and out to grip surfaces as they stretch and contract. Clitellum An enlarged area on the anterior end of the organism that secretes mucus aiding in the processes of reproduction Setae Bristles on each segment hat help the organism with locomotion (movement) The following positional terms are important when understanding the anatomy of the Earthworm. In shape the setae are nearly rectilinear, the nodule is moved towards the apex (fig. Ultrastructurally, the C. Digestive System: Mouth Mouth: tiny opening at anterior end through which food enters. The anus, the opening at the end of the digestive tract through which solid wastes are expelled, will be found at the posterior (hind) end. Leddmakk har eit lukka blodkarsystem med to hovudårer som går langs ryggen og buken langs heile kroppen. Unlike the homologous structure in terrestrial earthworms, the degree of prominence of the clitellum varies considerably in leeches. The number of segments making up the clitellum differ among species and can be an identifying characteristic. Bristles, called setae, are located on each segment. New baby worms will hatch from the cocoons and I will have a family. The clitellum will form a slime tube around it, which will fill with an albuminous fluid. This location is were fertilization takes place in an earthworm. Refer again to the diagram of the ventral view of the worm to locate and identify the external parts of its reproductive system. In summary, a reader asked us when earthworms die. This region contains glands that secrete the mucous in which the eggs are deposited. clitellum of an earthworm n. Clitellum: Mature worm bears a girdle like thick band of glandular tissue called clitellum which encircling the segments 14 to 16. Find the pair of sperm grooves that extend from the clitellum to segment 15, where one pair of male genital pores is located. The outer layer of earthworms' muscle is longitudinal. Observe the chaete. A worm is a long, creeping animal, with a soft, often segmented body. The most important sex organ in an earthworm is an organ named clitellum. tubelike structures found in pairs in every segment except the first three and the last. Segments 14 - 15 - 16 c. - feed on soil nutrients and decaying vegetation. The ring (clitellum) on adults is closer to the end than on nightcrawlers, milky pink to milky gray in color, encircles the whole body evenly, and is barely raised above the skin. Acknowledgement: Ross Gray. The Questidae have a partial clitellum and an oligochaetoid developmental pattern (Giere & Riser 1981). In shape the setae are nearly rectilinear, the nodule is moved towards the apex (fig. sperm grooves. Premature eggs that come out of their protective cocoons will shrivel and die. A fleshy lobe, the prostcmium, projects over the mouth in front of the first seg­ment. The Night Crawler (Lumbricus terrestris) is a large worm, measuring up to 25 cm in length and up to 1 cm in diameter. Finally, there's a rubbery, arm-band-like thing covering the worm's body from segments 31 or 32 to 37, and this is called the clitellum. Place the earthworm in the dissecting pan with the dorsal blood vessel on top. Clitellum: projecting girdle used for reproduction. The polychaetes are so named because of the numerous setae or chaetae they bear. The worms lie head to tail and side by side. may contain some organ systems that duplicate systems in other segments. setae, which are the minute bristle-like spines located on every segment except the first and last one. The setae and parapodia normally absent. The anus is on the dorsal surface just in front of the posterior sucker. Using the segment partitions on the diagram, let's see what makes up our compost friend. The clitellum, which was not fully developed in the type, covers segments (13) 14–18 (19)—that is, the dorsal surface of either or both the 13th and 19th may be glandular, but the segments are separated by a furrow from the rest of the organ. Most annelids have chitinous hairlike extensions in every segment called chaetae that are anchored in the epidermis, although the number and size of. About 48 chaetae on each segment, closely spaced except for wide mid-ventral gap. The cocoon, or egg case, is secreted by the clitellum, the external glandular band that is near the front of the worm, but behind the spermathecae. The bristles or setae help anchor and control the worm when moving through soil. GRAFF 2003, S. Look for the worm’s. Coxa: the first segment of the leg, joining the leg to the body. Body size of fixed adult holotype, 350 by 20 mm (30 mm at midpoint of clitellum); smaller adults and subadults 270-340 by 18-20 mm, according to degree of contraction (23 mm at clitellum). Sometimes, if you run your fingers on the underside (ventral) of the earthworm, you can feel the setae. The name, oligochaete, means few setae. It is about three-eighths of an inch wide with a circumference of 1 5/16 inches. On the ventral surface of 10th segement in the middle line a male genital opening is present. - 76 Clitellum absent. Earthworm external anatomy - label mouth, body segment, seta, clitellum, anus. The peristomium contains the mouth. Explain why the clitellum segment is thicker than the other segments? Why would this be important? 2. The most well-known species which have a clitellum are earthworms and leeches, on which the clitellum appears as a pale saddle-like structure a few segments down from their mouths. on StudyBlue. In front of peristomium there is a lobe like sensitive structure called prostomium. Colour dark nut-brown on dorsum, paler on ventrum. XVIII, a cylindrical body with perichaetine setae, caeca on segment XXVII, copulatory pouches without diverticula and stalked glands, bithecal spermatheca with nephridia, and the first spermathecal pore on segment 4/5. This lesson plan walks high school students through an earthworm dissection. Clitellum well developed, circular on ½21-½40. The clitellum develops into a cocoon, in which the new earthworms develop. Externally, a thin non-cellular cuticle covers the body wall of the earthworm. Genital setal glands. Dit dien om die eiers te bêre en te voed tot hulle uitbroei. I, #56, #57) is secondary within some modified Clitellata, because they are present in the basal clitellates. has a well developed brain that allows the annelid to learn simple tasks. It is the swelling located from segments 33 to 37 and is near the anterior end. Reproductive System of Earthworm Earthworms are hermaphrodites but they cannot fertilize their own eggs because of their relative position of male and female genital aperture and they are protrandous (i. Spermathecae intramuscular, around ab, 4-8 on each side in 14/15, 15/16. It will have 37 segments at the very least. The ventral nerve cord has branches which lead to lateral nerves and ganglia in each segment. They have complete alimentary canal with many crop and caeca. The designation of setae as. Det sidste segment indeholder anus. The shorter region to one side of the clitellum is the anterior or head-end of the animal. The glandular ring or saddle found on mature earthworms. These have few or no chetae per segment, and no nuchal organs or parapodia. The clitellum of each species of earthworm has a distinct colour, size, and shape. double pair of legs per segment and carnivorous lifestyle. Apart from the mouth and anus there are numerous openings on the worm's body. This swelling is called the clitellum. All segments of body except the first, last and clitellum have chitinous setae embedded in each segment. 2 und FÜLLER 1954, S. Numbers in the diagrams refer to the segment number. Usually there are 120 true somites. caliginosa (above) has GT on alternating and consecutive segments (27, 30, and 32 through 34). Setal arrangement perichaetine (Fig. Once the sperm has combined with the egg and it has become fertilized, the clitellum actually moves along the worms body. When mating time is at hand, two worms get together and appress their bodies, aligned in opposite directions. The clitellum may contain two ventral thickenings called tubercles. They arise from the inner surface of anterior wall of the respective testis sac. ’ ‘The two species display similar body length and segment number as well as show resemblance in the shape of the clitellum and tubercula pubertatis. As with other members of the oligochaetes, the aquatic species are hermaphrodites and feature the clitellum, a darker, enlarged body segment located toward the head of the animal. The shorter region to one side of the clitellum is the anterior or head-end of the animal. Oligochaetes live either in fresh water or on land. The last segment is called analsegment or pygidium. Be careful to only cut through skin… not through organs below. They have a clitellum, which is the bulge that forms during the reproductive part of their life cycle. Observe the clitellum —the thick unsegmented band which secretes the cocoon during reproduction. It extends from segment 55-100 (forty-six segments) and lies far behind the male pores, which are situated on penial processes arising from segments 18-20. Segments 14 - 15 - 16 c. External segments are called metameres. One can count the position of organs or pores by using the mouth or clitellum as the reference starting points. Testes– Reproductive gland in all male animals. side which is lighter in color. The setae look like small bristles sticking out of the earthworm’s skin. male sex mature earlier than female gametes). The sixth segment contains a modified pair of uropods. Locate the clitellum, which extends from segment 33 to segment 37. One pair is situated at 10 th segment and another pair at 11 th segment. When an earthworm has mated, the clitellum will secrete a sack of eggs.