Umbo bivalve The beak usually, but not always, coincides with the umbo, the highest and most prominent point on the valve. umbones) The first part of a brachiopod (Brachiopoda) or bivalve shell to be formed. In many bivalves the hinge carries a series of interlocking teeth, but these structures are absent in the family Ostreidae. Os bivalves são os únicos moluscos que não têm rádula [2] e alimentam-se por filtração através dos sifões, as únicas partes do corpo mole que estes organismos conseguem fazer sair da concha. The oldest part of the shell, the umbo, can be recognized as a large hump on the anterior end of the dorsal side of each shell. ). Dec 1, 2016 · I hypothesize that the development of the immune system is inextricably linked with the formation of the digestive system in bivalves (Fig. Body whorl – the large whorl, containing the aperture, in which the snail lives. The lunule or indented side will be on the left. Sep 25, 2023 · Because bivalve valves are generally equivalved, outlines are generally more important than profiles for defining their shapes. Thehinge consists of the umbo cardinal tooth lateral tooth anterior border left valve right valve umbo lunule thickness (degree of inflation) Glossary of Bivalve Terms Beak (or umbo - plural: umbos or umbones) : the first formed part of a valve, usually above the hinge. Bivalves have two siphons May 1, 2009 · Traditional terms used to describe shell orientation in bivalves are unsatisfactory in three important ways: 1) for poorly known bivalve taxa, unbiased and directionally neutral terms are Each of the two parts of a bivalve shell, joined by a ligament. Mollusks also have a radula or file-like organ for… The umbo (plural umbones or umbos) is the vaguely defined, often most prominent, highest part of each valve of the shell of a bivalve or univalve mollusc. L'umbo présente le plus souvent un crochet (les deux termes - crochet et umbo - sont souvent pris comme synonymes) et détermine le bord dorsal de la coquille. In a brachiopod, the umbo is the posterior part of each valve; in a bivalve it forms the dorsal part of the shell. [9] The hinge area is the dorsum or back of the shell. Le crochet est, dans la plupart des cas recourbé vers l'avant de la coquille (crochet prosogyre), plus rarement, vers l'arrière (crochet opisthogyre), ou dirigé vers l'autre valve Download scientific diagram | Basic bivalve shell morphology. known as umbo. [3] The hinge ligament of a bivalve shell can be either internal, external, or both, and is an example of complex development. Jan 5, 2023 · Right and left valves. The ligament is the cartilage that connects the valves of bivalves. Byssal Threads (Byssus): Bundle of threads used by mussels to attach to hard surfaces. extant species), and the ligaments can be reconstructed in most fossil bivalves based on their sites of attachment on the shell. The bulge near the hinge is called the umbo and is the oldest part of the shell. Mar 24, 2008 · This chapter examines the phylogeny and evolution of the molluscan class Bivalvia. Most soft-bodied, aquatic animals with two shells fall into this group. Aug 15, 2024 · Procedure: Phase 1: Bivalve external anatomy - identify external structures Use blunt probe to identify the umbo 1. The earlier trochophore larval stage is a key stage in bivalve development when the first ciliated digestive organs such as the mouth, esophagus, and digestive mass (anlagen of the stomach) form, allowing larvae to begin to filter feed on microalgae Apr 15, 2021 · Diet has been widely reported as the main limiting factor for the growth and survival of bivalve larvae (Avila et al. Bivalve - a laterally compressed mollusk with 2 valves (2 "half-shells"). Scallops swim by clapping their shells together. It is suggested that Glu may play a key role in the settlement of bivalve larvae. Not all bivalve shells have an umbo. May 31, 2024 · The dorsal part contains an umbo (the highest part of the shell valve) and a beak (basal projection of the shell), joined by the hinge point. Prodissoconch - shell in larval state remaining on the umbonal region of well-preserved bivalve shells. Pallial line •Where mantle is attached to shell. Geralmente há dois sifões, servindo um para aspirar a água carregada de pequenos organismos e algas e o outro para expelir. The lower, curved margin is the ventral side. May 27, 2022 · Umbo: The dorsal part of a valve where curvature increases significantly; this region also contains the beak. Dosinia is a rapid burrower with a very circular generating curve). Lateral teeth can be absent in some species. If the adductor muscles are relaxed, the shell is pulled open by ligaments located on each side of the umbo. Valve : Each shell of the bivalve mollusc. The valves are joined at the top, and the adductor muscles on each side hold the shell closed. previous. An abnormally placed borehole (D) and incomplete boreholes (E, I flow such that the umbo faces upstream. (B) Scheme of the adopted convention for asymmetrical valve sides. Folds of the mantle margin form the exhalant and inhalant siphons. A band of horny and elastic material, the ligament (fig. Place the valve flat in front of you opening side down with the umbo pointing away. O que são bivalves? Bivalves, ou Bivalvia, referem-se a uma classe de animais que vivem em água doce e salgada. Taxonomy, Anatomy & Biology of Bivalve Mollusks: Hard Clams and Oysters. Internal bivalve morphology. , accounting for 66. Jan 26, 2001 · A bivalve is characterized by possessing two shells secreted by a mantle that extends in a sheet on either side of the body. Each valve can be regarded as having; dorsal, ventral, anterior and posterior margins. It usually contains the valve's beak, the oldest point of the valve, and its degree of prominence and its position relative to the hinge line are sometimes helpful in distinguishing bivalve taxa. The oldest point of a bivalve shell is called the beak, and the raised area around it is known as the umbo (plural umbones). Umbos et manipule - a : coques séparées de l'umbo, tombe 3 ; b : hypothèse de remontage sur la spina ; c : coupe de l'umbo, tombe 1 ; d : manipule, tombe 1 ; e : hypothèse de reconstitution de l'umbo bivalve sur la spina, avec la nervure médiane en bois (dessin de l'auteur). You can use it as Bivalve (Clam) Diagram practice, completely free to play. Powerful muscles contract ligaments to keep the valves closed and relax to open them. The valves are usually similar to one another in size, shape, color, and texture. shell umbo Protuberance at the terminal end of the valve, from which the shell grows. This is a more derived kind of bivalve hinge. Study with Quizlet and memorize flashcards containing terms like The oldest part of the shell of a bivalve is called the ______ and it is located on the _______ of the shell. canal or umbo to lateral margin. umbo, left side B. 4 Mt. Nov 27, 2018 · The bivalve production has been gradually increasing. Clams are bivalves meaning they have shells consisting of two halves, or valves. It discusses the diversity and abundance of bivalves, evaluates their economic significance and human impacts and A pearl is formed when a foreign object gets stuck in the bivalve such as sand grain. Adductor muscle scars: Variably shaped scars where the animal’s adductor muscles are attached to the shell. extralimital: beyond the edge of a species natural geographical range. It usually contains the valve's beak, the oldest point of the valve, and its degree of prominence and position relative to the hinge line are sometimes helpful in distinguishing bivalve taxa. [2] Most of the bivalve body is located dorsally in the shell. Bivalves have a right valve and left valve. Make a bivalve with your hands. Learn vocabulary, terms, and more with flashcards, games, and other study tools. Bivalves are filter feeders and accumulate inorganic elements and organic compounds from the water column through ingestion of sediment particles (Jing et al. umbo, dorsal side C. Os dentes da charneira estão dispostos em uma única fila, porém em lugares separados. (b) Schematic of the cross-section of a shell showing the growth The umbo is the swelling part of a bivalve near the beak. Download scientific diagram | Diagram of a valve of a bivalve (open, spoon-like shells), with the umbo or 'beak' (u) and hinge-teeth circled. ITZ Possuem conchas prismáticas nacaradas, alongadas tal como nos mexilhões. The trocophore is a ciliated, free-swimming stage. – In rostrate opisthogyrate bivalves, the umbo and the postero-dorsal angle of the shell project dorsally relative to the ligament, which then fails to act as a pivotal axis. oldest part of the shell of a bivalve from which the shell grows. Bivalve cultured in China have obvious geographical distribution characteristics, among which clams and oysters are all over the country culture species. Umbone is another word for umbo. Dec 1, 2017 · Ichnospecies Oichnus paraboloides Bromley found in three bivalve shells: A–J, Mactra chinensis; K, Nuttallia japonica; L–O, Felaniella usta; Note that most boreholes in the shells of M. The umbo (plural umbones or umbos) is the vaguely defined, often most prominent, highest part of each valve of the shell of a bivalve or univalve mollusc. the umbo (plural, umbos or umbones) or beak. Bifid: split in two (as in the tooth in the hinge). Bivalve: A mollusk w/ 2 hinged shells, includes clams, oysters, and mussels. the bundled muscle farthest away from the umbo; the . These are said to be o pisthogyral. foot Jan 1, 2010 · The nature of each valve of the bivalve shell is that of a spiral, homologous to that of a gastropod. The side of the shell with the hinge is dorsal and the opposite side (i. The freshwater mussel Mytilopsis leucophaeata showing the incurrent and excurrent siphons. next. , 2010; Velasco and Barros, 2010; Liu et al. Radial - structures that are directed away from the umbo toward the shell margin in bivalve shells. 16) joins the valves at the hinge on which they turn in opening or closing the shell. This is an online quiz called Bivalve (Clam) Diagram. The region opposite is the ventral margin. Move mussel to dissecting microscope 4. 1). The vulnerability of the umbo to perforation is greatly increased by the thinness of the shell at the umbo cavity. Bivalves d’eau douce de Nouvelle-Aquitaine. Mar 25, 2019 · The umbo (plural umbones or umbos) is the vaguely defined, often most prominent, highest part of each valve of the shell of a bivalve or univalve mollusk. accumulate heavy metals at higher rates into the shell matrix. Pseudocardinal teeth are well developed and long; lateral teeth are straight and thick. Definition. e. Eles pertencem ao filo Mollusca, que são mais comumente chamados de ‘moluscos’. Umbo: (aka beak) The curved protrusions at the base of each valve representing the initial growth of the bivalve. Umbo . Tais dentes divergem desde o umbo. It usually contains the valve's beak , the oldest point of the valve, and its degree of prominence and position relative to the hinge line are sometimes helpful in distinguishing bivalve taxa Jan 5, 2023 · Right and left valves. , 2022; Zhang et al. , 1997; Pettersen et al. This challenge, present in several bivalve groups, has been functionally solved in different, and sometimes complementary, ways. Nov 19, 2012 · The document discusses bivalve mollusks such as mussels, clams, oysters, and scallops. The shorter of the two valves is the right valve. Obviously, young, fast growing and intensely respiring bivalves accumulate heavy metals at higher rates into the shell matrix than older animals. Use blunt probe to identify oldest line of growth 2. Jan 1, 2017 · Umbo sculpture is strictly nodulous and usually restricted to the umbo area but in some cases more widespread. The shells provide protection for the clam and are opened and closed by two adductor muscles located on either side of the hinge. Varix (varices – plural): Thickened ridges seen at the edge of the outer lip of shell. The umbo is anterior to the externally visible portion of the hinge ligament. 3. Aug 26, 2020 · The umbo, and its tip which is called the peak, is the first part of the shell secreted. Aside from the umbo, the Près de la charnière de la coquille, on trouve l'umbo, une protubérance noueuse et arrondie. chinensis are located on the umbo of the right valve (A–C) and the left valve (F–H). , 2006). Bivalves, which are part of Class Bivalvia, are enclosed in a pair of shells or valves that are joined at the umbo, the initial point of shell growth. Plus généralement, l'acceptation vaut pour toute pièce faisant saillie. The umbo or hinge area, where the valves are joined together, is the dorsal part of the animal (Figure 6). As nouns the difference between bivalve and umbo is that bivalve is any mollusc belonging to the taxonomic class bivalvia, characterized by a shell consisting of two hinged sections, such as a scallop, clam, mussel or oyster while umbo is 3- ligamento, 4- umbo. Beak Sculpture - (see also: Concentric scuplture) - shape and arrangement of contours inherent to umbo; formed by early growth geometry. , 2016). In bivalve mollusks, the siphon through which incoming water enters the body. Concentric grooves – grooves which spread out from the umbo like ripples, Clam Dissection Introduction The phylum Mollusca includes snails, clams, chitons, slugs, limpets, octopi, and squid. . Use blunt probe to scratch away top layer of shell 3. It defines key anatomical features including the umbo, pallial line, and adductor muscles. The area surrounding the beak is known as the umbo although some regard these terms as interchangeable. As mollusks develop from a fertilized egg to an adult, most pass through a larval stage called the trocophore. beak-like projections at the dorsal part of the shell; it is the oldest part of a bivalve shell (also called the umbone) Upwelling . In most bivalves (including Mercenaria), the umbo points towards the anterior side and the ligament and escutcheon towards the posterior side. Hinge teeth located directly below the umbo in a heterodont hinge. 4- coquille oblongue à umbo net, épaisse, taille entre 10 et 25 mm, surface fortement ridée, présence d’un dent triangulaire près du septum (1) Mar 16, 2025 · Bivalve (Clam) Diagram — Quiz Information. On each side of the hinge, anterior to the ligament, each valve displays a raised area known as theumbo, or beak (plural = umbones) (Fig 1, Fig 12-92B). Question 16 (Mandatory) (1 point) The plane that divides left from right in a bivavle is located across the outer edge of the mantel through the hinge and down the middle of the shells between the two shells across the hinges and through both shells Question 17 (Mandatory) (1 point) The umbo of a bivalve shell forms at the radula protoconch anterior canal outer lip Question 18 (Mandatory) (1 The concentric lines found around the umbo are growth lines, which are usually seasonal, making it a lot easier to tell the age of a bivalve than a gastropod! The two valves are attached by an elastic band of cartilage-like material called the hinge ligament, which is made up of conchiolin - the same as the periostracum. The ridges that form around the umbo trace the growth of the valve. The bivalve aquaculture production in 2015 was 12. Obviously, young, fast growing and intensely respiring biv alves. The shell is composed of different layers including an outer organic layer, a middle prismatic layer, and an inner smooth nacreous layer. Oct 30, 2007 · Moreover, it coincides with the end of the decrease in element accretion in the umbo between 6 and 8 years of bivalve age. However, since the size and shape of an oyster can be influenced by its environment Umbo : Beak of a bivalve shell, from where generally the growth of the shell would have started. Nas espécies que se enterram no sedimento, as margens do manto estão unidas e a entrada e saída da corrente de água é feita através de dois sifões (um inalante e outro exalante). periostracum, right side, The adaptation of bivalves to a sedentary, filter-feeding lifestyle that exploits the sand of a beach as a habitat, has Dec 3, 2023 · The oldest part of a bivalve shell is called the umbo. excurrent siphon: opening through which mussel expels water, wastes, and glochidia. Diagram of the left valve of a bivalve resembling a veneridA side view of a whole shell of Cucullaea labiata (Lightfoot, 1786), the umbones are at the top of the imageDiagram of a bivalve shell 4:Umbo; 3:Ligamento O umbo é o vértice; a parte mais antiga das valvas de um molusco bivalve, próximas a seu ligamento (estrutura que une ambas as valvas). Umbo (bivalve), part of a bivalve shell which was formed when the animal was a juvenile; Umbo (conifer cone), the first year's growth of a seed scale on a conifer cone, showing up as a protuberance at the end of the two-year-old scale; Umbo (mycology), at the top of some mushrooms Bivalvia (/ b aɪ ˈ v æ l v i ə /) or bivalves, in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of aquatic molluscs (marine and freshwater) that have laterally compressed soft bodies enclosed by a calcified exoskeleton consisting of a hinged pair of half-shells known as valves. periostracum, ventral side D. This technique, it needs to be noted, works for most bivalves, because the umbos are at or near, and directed towards, the front of the organism (the technical term for this arrangement is prosogyral). The two shells are joined at the dorsal end by a region called the ligament. bivalve: a mollusk with two shells. A. ‘Bi’ significa dois e ‘válvula’ é realmente ‘valva’, que significa ‘folhas […] May 8, 2018 · umbo (pl. Bivalvia (pelafalan Inggris: / b aɪ ˈ v æ l v i ə /) adalah kelas dalam moluska yang mencakup semua kerang-kerangan: memiliki sepasang cangkang (nama "bivalvia" berarti dua cangkang). En mycologie, un umbo est une zone surélevée au centre d'un chapeau de champignon. Classify ‐ The arrangement of anything into groups or categories. Within it can be a variety of combinations of teeth and sockets that articulate the two valves. The lunule is a heart-shaped depressed area in front of the umbo in many clams. AM - Músculo adutor; GO - gónadas; M - manto; U - umbo . Nov 10, 2020 · Many burrowing bivalves are elongated parallel to the umbo (e. The outer surface of these shells is often intricately sculpted into concentric rings (helpful in age determination), radial ribs, or lattice-like patterns. (A) Scheme of shell axis orientation. A subclasse Heterodonta é conhecida por abrigar os chamados mexilhão-zebra. Observe lines of growth (concentric rings radiating away from the umbo). Varices show different patterns. denticals: a small, tooth-like projection. [1] En los Sphaeriidae, los caracteres taxonómicos más confiables a nivel de género son la forma y el número de sifones, y el tamaño de ambas hemibranquias; a nivel específico, son la morfometría y morfología de las valvas, la que incluye, posición del umbo, características de la charnela, forma y tamaño de los dientes cardinales Review of characteristics and example organisms of the Phylum Mollusca (Bivalves, Gastropods and Cephalopods). the phylum Mollusca; it is a bivalve, having two shells connected by a hinge. [1] In many species of bivalves the beaks point towards one another. Figura 2 - Circuito da água nas brânquias de um molusco bivalve. Right valve: The entire right half of Bivalves have a muscular "foot" at their front end that is used for movement such as burrowing, or in some bivalves like the razor clams, for swimming. in hatchery terminology, a growing system in which a flow of water is induced through the base of a spat holding container (compare with downwelling). Microalgae are the major dietary source for bivalves, which contain various nutrients for larval growth and development (Knauer and Southgate, 1999). The left valve of a clam can be identified as follows. The shape and structure of the hingeline, ligament area, the position and angle of the beak/umbo area, and the presence and angle of posterior ridges are also important in describing some bivalve shapes. posterior end umbo Protuberance at the terminal end of the valve, from which the shell grows. In the blue mussels mentioned above, the foot is primarily used to create byssal threads. The hinge is located on the dorsal side of the clam next to a structure/location called the umbo. The mantle cavity in bivalves is located ventrally and laterally. Internal Clam L'umbo (pluriel umbones ou umbos, du latin umbo, « bosse, protubérance »), est l'extrémité saillante des valves d'un mollusque bivalve ou univalve. Because by definition, all bivalves have two valves, the shell of a bivalve has two umbones, and two beaks. , margin of shell growth) is ventral. (radiating from the umbo, or beak, of the shell) and more remote lateral teeth Lateral Teeth: Hinge teeth located far away from the umbo in a heterodont hinge. Muitas vezes eles estão inclinados para a frente (prosogiro), frequentemente voltados para trás (opistogiro) [1] ou na vertical (ortogiro). The valve on the left is the left valve and the valve on the right is the right valve. Beak ‐ umbo Bivalve –oa tw piece shell. Prior to the development of the umbo, during the early veliger or D-hinge stage, larvae can be extremely difficult to differentiate and, without the use of scanning electron microscopy, probably cannot be taken down to species. The umbo is the oldest part of the shell. Cette protubérance souvent noueuse et arrondie se forme lorsque l'animal est jeune ( prodissoconque ), et la coquille de celui-ci s'agrandit radialement autour de cet umbo. Rising above the hinge line on each valve is a swelling called the umbo, the oldest part of the shell. Describing bivalves, it’s necessary to pay attention to the hinge (cardinal area). Any whole shell, or any piece of shell with this Umbo. Radiating - same as radial. (from Mikkelsen and Bieler, 2008) from publication Download scientific diagram | (a) Shell section cut from the umbo to the posterior ventral edge of the freshwater bivalve shell. May 1, 2023 · Shape of bivalve shells. The umbo can take on a variety of shapes and sizes, most of which are species-specific. Distribution: Lanceolariini are restricted to Far East Asia, from the Amur River basin (Russia) to Japan, Korea, the Pacific basins of China and Each of the two parts of a bivalve shell, joined by a ligament. Inside the shell, the animal has a simple head without eyes or radula (the rasping, ribbon-like tongue used for feeding in other mollusc groups). In Protobranchia, however, the umbo is situated at, and points towards, the posterior. Now keep your thumbs together, and open your pinky finger side of the cup. Taxonomy Umbo 8. Keep your hands cupped. The basic features of a valve are labelled. Now bring your cupped hands together so that both your thumbs are touching. O nome bivalve vem do latim, como a maioria das classificações biológicas. En biologie, un umbo désigne l'ombilic, une partie saillante comme le crochet dans la coquille des bivalves. 4. 0% of the total marine aquaculture production. Compare/contrast movement in the clan and the scallop. So that when you hold the left hand/side shell with the inner surface towards you it looks like the diagram above. , 2023). The only vestige of this growth pattern is the umbo or beak of each valve. Hinge: Toothed area at the umbo beneath the beak and ligament that helps hold the two shells together in bivalves. [5] Various types of hinge ligaments have been found in living species (i. The first thing you need to do is make cups with both of your hands. The beaks effectively divide the dorsal margin into anterodorsal and posterodorsal parts. This is what a bivalve looks like. Cette protubérance souvent noueuse et arrondie se forme lorsque l'animal est jeune (prodissoconque), et la coquille de celui-ci s'agrandit radialement autour de cet umbo. Whorl : One complete ( 360° ) coil of a shell About the external shell, the convex "hump" at the top of the shell is called umbo. According to Animal Diversity Web: A bivalve is characterized by possessing two shells secreted by a mantle that extends in a sheet on either side of the body. The foot of bivalves is described as extendable and used for digging or swimming. Note: Typically, the right valve of an oyster will be shorter and less concave than the left valve. The elevated, upstream-facing umbo region is exposed to particle impact and is the first to be abraded and perforated. planktonic stage of bivalve embryo . Urogenital System anatomy of a bivalve shell. The mantle secretes CaCO3 around the object, creating the pearl. In those that do the umbo often seems to point to one side or another, usually to the anterior side. Two muscle scars are present in most equivalve species near the anterior and posterior margins of Posterior - in bivalves, the region of the shell sinus away from the foot. Dec 29, 2024 · During the development of bivalves, particularly in the later stages of umbo larvae, neural remodeling becomes a necessary biological process for the formation of critical neural organs like eye spots and foot (Zeng et al. extirpated: to be absent from a specific locality. A bivalve, though, expands the diameter of its aperture very quickly relative to its rotation about the coiling axis, nearly obliterating any sense of its coil [514]. Sous le crochet de certains bivalves, chaque valve présente une aire plus ou moins développée, d'allure triangulaire allongée, nommée le plateau cardinal, qui porte le ligament Nov 21, 2023 · Oysters, clams, mussels, scallops, cockles, coquinas, and many more are all part of the class Bivalvia. A prodissoconch (meaning first or earliest or original shell) is an embryonic or larval shell which is present in the larva of a bivalve mollusk (clams, scallops, oysters, etc. , Ensis, Mya) although exceptions exist (e. When the exterior of a bivalve shell is oriented with its hinge and umbo (and beak) upward and its commissure (valve-opening margin) downward, and the umbo (and beak) farther away from you (dorsal-anterior side of the shell), the right valve is on your right side, and the left valve is on the left side. Nov 1, 2007 · accretion in the umbo between 6 and 8 years of bivalve age. Oct 30, 2007 · The analysis of the element composition of bivalve shells has gained importance in recent years with respect to environmental monitoring. [1] Bivalvia(Bivalves) Phylum MolluscaClass BivalviaNumber of families 105Thumbnail description Bilaterally symmetrical mollusks, with a reduced head and typically two external shell valves, many of which are commercially important for human consumption and pearl production; some have major impacts on the world economy and environment Source for information on Bivalvia (Bivalves): Grzimek's Animal L'umbo (pluriel umbones ou umbos, du latin umbo, « bosse, protubérance »), est l'extrémité saillante des valves d'un mollusque bivalve ou univalve. Concentric: Ridges or lines parallel to shell margin. Notice how the umbo end of the longer valve, the left valve, extends beyond the umbo end of the right valve. g. Most of the mantle cavity is occupied by the paired ctenidia, which in bivalves perform not only their original Bivalves do not have obvious head or tail regions, but anatomical terms used to describe these areas in other animals are applied to them. The two umbos almost touch across the midline. The in situ abrasion process is The oldest point of a bivalve shell is called the beak, and the raised area around it is known as the umbo (plural umbones). Ficha Técnica dos Bivalves: Peso, Altura, Tamanho e Imagens Start studying Bivalvia (Clam Dissection Labeling). (a) and (b) are the base axes, (c) is the shell height. Beak (see also: Umbo) - dorsal protuberance on bivalve shell that generally rises above the hinge; the oldest part of the shell. No-one ever said that Umbo view of one valve of Dosina japonica with prodissoconch visible Umbo view of paired valves of Chione subrugosa with prodissoconchs visible. The umbo is circular in shape and is the Contents 1See also 2References A left valve of a juvenile Mercenaria campechiensis viewed from the dorsal aspect in order to show the brown-tinted lunule on the right, next to the forward facing umbo. vxuzynqbylqfpmjnpqqotcxjubscxghpnhiablekaylvuzkbzpqpbwxhadowxyurrjjylvzcsarpepdzkh
Umbo bivalve The beak usually, but not always, coincides with the umbo, the highest and most prominent point on the valve. umbones) The first part of a brachiopod (Brachiopoda) or bivalve shell to be formed. In many bivalves the hinge carries a series of interlocking teeth, but these structures are absent in the family Ostreidae. Os bivalves são os únicos moluscos que não têm rádula [2] e alimentam-se por filtração através dos sifões, as únicas partes do corpo mole que estes organismos conseguem fazer sair da concha. The oldest part of the shell, the umbo, can be recognized as a large hump on the anterior end of the dorsal side of each shell. ). Dec 1, 2016 · I hypothesize that the development of the immune system is inextricably linked with the formation of the digestive system in bivalves (Fig. Body whorl – the large whorl, containing the aperture, in which the snail lives. The lunule or indented side will be on the left. Sep 25, 2023 · Because bivalve valves are generally equivalved, outlines are generally more important than profiles for defining their shapes. Thehinge consists of the umbo cardinal tooth lateral tooth anterior border left valve right valve umbo lunule thickness (degree of inflation) Glossary of Bivalve Terms Beak (or umbo - plural: umbos or umbones) : the first formed part of a valve, usually above the hinge. Bivalves have two siphons May 1, 2009 · Traditional terms used to describe shell orientation in bivalves are unsatisfactory in three important ways: 1) for poorly known bivalve taxa, unbiased and directionally neutral terms are Each of the two parts of a bivalve shell, joined by a ligament. Mollusks also have a radula or file-like organ for… The umbo (plural umbones or umbos) is the vaguely defined, often most prominent, highest part of each valve of the shell of a bivalve or univalve mollusc. L'umbo présente le plus souvent un crochet (les deux termes - crochet et umbo - sont souvent pris comme synonymes) et détermine le bord dorsal de la coquille. In a brachiopod, the umbo is the posterior part of each valve; in a bivalve it forms the dorsal part of the shell. [9] The hinge area is the dorsum or back of the shell. Le crochet est, dans la plupart des cas recourbé vers l'avant de la coquille (crochet prosogyre), plus rarement, vers l'arrière (crochet opisthogyre), ou dirigé vers l'autre valve Download scientific diagram | Basic bivalve shell morphology. known as umbo. [3] The hinge ligament of a bivalve shell can be either internal, external, or both, and is an example of complex development. Jan 5, 2023 · Right and left valves. The ligament is the cartilage that connects the valves of bivalves. Byssal Threads (Byssus): Bundle of threads used by mussels to attach to hard surfaces. extant species), and the ligaments can be reconstructed in most fossil bivalves based on their sites of attachment on the shell. The bulge near the hinge is called the umbo and is the oldest part of the shell. Mar 24, 2008 · This chapter examines the phylogeny and evolution of the molluscan class Bivalvia. Most soft-bodied, aquatic animals with two shells fall into this group. Aug 15, 2024 · Procedure: Phase 1: Bivalve external anatomy - identify external structures Use blunt probe to identify the umbo 1. The earlier trochophore larval stage is a key stage in bivalve development when the first ciliated digestive organs such as the mouth, esophagus, and digestive mass (anlagen of the stomach) form, allowing larvae to begin to filter feed on microalgae Apr 15, 2021 · Diet has been widely reported as the main limiting factor for the growth and survival of bivalve larvae (Avila et al. Bivalve - a laterally compressed mollusk with 2 valves (2 "half-shells"). Scallops swim by clapping their shells together. It is suggested that Glu may play a key role in the settlement of bivalve larvae. Not all bivalve shells have an umbo. May 31, 2024 · The dorsal part contains an umbo (the highest part of the shell valve) and a beak (basal projection of the shell), joined by the hinge point. Prodissoconch - shell in larval state remaining on the umbonal region of well-preserved bivalve shells. Pallial line •Where mantle is attached to shell. Geralmente há dois sifões, servindo um para aspirar a água carregada de pequenos organismos e algas e o outro para expelir. The lower, curved margin is the ventral side. May 27, 2022 · Umbo: The dorsal part of a valve where curvature increases significantly; this region also contains the beak. Dosinia is a rapid burrower with a very circular generating curve). Lateral teeth can be absent in some species. If the adductor muscles are relaxed, the shell is pulled open by ligaments located on each side of the umbo. Valve : Each shell of the bivalve mollusc. The valves are joined at the top, and the adductor muscles on each side hold the shell closed. previous. An abnormally placed borehole (D) and incomplete boreholes (E, I flow such that the umbo faces upstream. (B) Scheme of the adopted convention for asymmetrical valve sides. Folds of the mantle margin form the exhalant and inhalant siphons. A band of horny and elastic material, the ligament (fig. Place the valve flat in front of you opening side down with the umbo pointing away. O que são bivalves? Bivalves, ou Bivalvia, referem-se a uma classe de animais que vivem em água doce e salgada. Taxonomy, Anatomy & Biology of Bivalve Mollusks: Hard Clams and Oysters. Internal bivalve morphology. , accounting for 66. Jan 26, 2001 · A bivalve is characterized by possessing two shells secreted by a mantle that extends in a sheet on either side of the body. Each valve can be regarded as having; dorsal, ventral, anterior and posterior margins. It usually contains the valve's beak, the oldest point of the valve, and its degree of prominence and its position relative to the hinge line are sometimes helpful in distinguishing bivalve taxa. The oldest point of a bivalve shell is called the beak, and the raised area around it is known as the umbo (plural umbones). Umbos et manipule - a : coques séparées de l'umbo, tombe 3 ; b : hypothèse de remontage sur la spina ; c : coupe de l'umbo, tombe 1 ; d : manipule, tombe 1 ; e : hypothèse de reconstitution de l'umbo bivalve sur la spina, avec la nervure médiane en bois (dessin de l'auteur). You can use it as Bivalve (Clam) Diagram practice, completely free to play. Powerful muscles contract ligaments to keep the valves closed and relax to open them. The valves are usually similar to one another in size, shape, color, and texture. shell umbo Protuberance at the terminal end of the valve, from which the shell grows. This is a more derived kind of bivalve hinge. Study with Quizlet and memorize flashcards containing terms like The oldest part of the shell of a bivalve is called the ______ and it is located on the _______ of the shell. canal or umbo to lateral margin. umbo, left side B. 4 Mt. Nov 27, 2018 · The bivalve production has been gradually increasing. Clams are bivalves meaning they have shells consisting of two halves, or valves. It discusses the diversity and abundance of bivalves, evaluates their economic significance and human impacts and A pearl is formed when a foreign object gets stuck in the bivalve such as sand grain. Adductor muscle scars: Variably shaped scars where the animal’s adductor muscles are attached to the shell. extralimital: beyond the edge of a species natural geographical range. It usually contains the valve's beak, the oldest point of the valve, and its degree of prominence and position relative to the hinge line are sometimes helpful in distinguishing bivalve taxa. [2] Most of the bivalve body is located dorsally in the shell. Bivalves have a right valve and left valve. Make a bivalve with your hands. Learn vocabulary, terms, and more with flashcards, games, and other study tools. Bivalves are filter feeders and accumulate inorganic elements and organic compounds from the water column through ingestion of sediment particles (Jing et al. umbo, dorsal side C. Os dentes da charneira estão dispostos em uma única fila, porém em lugares separados. (b) Schematic of the cross-section of a shell showing the growth The umbo is the swelling part of a bivalve near the beak. Download scientific diagram | Diagram of a valve of a bivalve (open, spoon-like shells), with the umbo or 'beak' (u) and hinge-teeth circled. ITZ Possuem conchas prismáticas nacaradas, alongadas tal como nos mexilhões. The trocophore is a ciliated, free-swimming stage. – In rostrate opisthogyrate bivalves, the umbo and the postero-dorsal angle of the shell project dorsally relative to the ligament, which then fails to act as a pivotal axis. oldest part of the shell of a bivalve from which the shell grows. Bivalve cultured in China have obvious geographical distribution characteristics, among which clams and oysters are all over the country culture species. Umbone is another word for umbo. Dec 1, 2017 · Ichnospecies Oichnus paraboloides Bromley found in three bivalve shells: A–J, Mactra chinensis; K, Nuttallia japonica; L–O, Felaniella usta; Note that most boreholes in the shells of M. The umbo (plural umbones or umbos) is the vaguely defined, often most prominent, highest part of each valve of the shell of a bivalve or univalve mollusc. the umbo (plural, umbos or umbones) or beak. Bifid: split in two (as in the tooth in the hinge). Bivalve: A mollusk w/ 2 hinged shells, includes clams, oysters, and mussels. the bundled muscle farthest away from the umbo; the . These are said to be o pisthogyral. foot Jan 1, 2010 · The nature of each valve of the bivalve shell is that of a spiral, homologous to that of a gastropod. The side of the shell with the hinge is dorsal and the opposite side (i. The freshwater mussel Mytilopsis leucophaeata showing the incurrent and excurrent siphons. next. , 2010; Velasco and Barros, 2010; Liu et al. Radial - structures that are directed away from the umbo toward the shell margin in bivalve shells. 16) joins the valves at the hinge on which they turn in opening or closing the shell. This is an online quiz called Bivalve (Clam) Diagram. The region opposite is the ventral margin. Move mussel to dissecting microscope 4. 1). The vulnerability of the umbo to perforation is greatly increased by the thinness of the shell at the umbo cavity. Bivalves d’eau douce de Nouvelle-Aquitaine. Mar 25, 2019 · The umbo (plural umbones or umbos) is the vaguely defined, often most prominent, highest part of each valve of the shell of a bivalve or univalve mollusk. accumulate heavy metals at higher rates into the shell matrix. Pseudocardinal teeth are well developed and long; lateral teeth are straight and thick. Definition. e. Eles pertencem ao filo Mollusca, que são mais comumente chamados de ‘moluscos’. Umbo: (aka beak) The curved protrusions at the base of each valve representing the initial growth of the bivalve. Umbo . Tais dentes divergem desde o umbo. It usually contains the valve's beak , the oldest point of the valve, and its degree of prominence and position relative to the hinge line are sometimes helpful in distinguishing bivalve taxa Jan 5, 2023 · Right and left valves. , 2022; Zhang et al. , 1997; Pettersen et al. This challenge, present in several bivalve groups, has been functionally solved in different, and sometimes complementary, ways. Nov 19, 2012 · The document discusses bivalve mollusks such as mussels, clams, oysters, and scallops. The shorter of the two valves is the right valve. Obviously, young, fast growing and intensely respiring bivalves accumulate heavy metals at higher rates into the shell matrix than older animals. Use blunt probe to identify oldest line of growth 2. Jan 1, 2017 · Umbo sculpture is strictly nodulous and usually restricted to the umbo area but in some cases more widespread. The shells provide protection for the clam and are opened and closed by two adductor muscles located on either side of the hinge. Varix (varices – plural): Thickened ridges seen at the edge of the outer lip of shell. The umbo is anterior to the externally visible portion of the hinge ligament. 3. Aug 26, 2020 · The umbo, and its tip which is called the peak, is the first part of the shell secreted. Aside from the umbo, the Près de la charnière de la coquille, on trouve l'umbo, une protubérance noueuse et arrondie. chinensis are located on the umbo of the right valve (A–C) and the left valve (F–H). , 2006). Bivalves, which are part of Class Bivalvia, are enclosed in a pair of shells or valves that are joined at the umbo, the initial point of shell growth. Plus généralement, l'acceptation vaut pour toute pièce faisant saillie. The umbo or hinge area, where the valves are joined together, is the dorsal part of the animal (Figure 6). As nouns the difference between bivalve and umbo is that bivalve is any mollusc belonging to the taxonomic class bivalvia, characterized by a shell consisting of two hinged sections, such as a scallop, clam, mussel or oyster while umbo is 3- ligamento, 4- umbo. Beak Sculpture - (see also: Concentric scuplture) - shape and arrangement of contours inherent to umbo; formed by early growth geometry. , 2016). In bivalve mollusks, the siphon through which incoming water enters the body. Concentric grooves – grooves which spread out from the umbo like ripples, Clam Dissection Introduction The phylum Mollusca includes snails, clams, chitons, slugs, limpets, octopi, and squid. . Use blunt probe to scratch away top layer of shell 3. It defines key anatomical features including the umbo, pallial line, and adductor muscles. The area surrounding the beak is known as the umbo although some regard these terms as interchangeable. As mollusks develop from a fertilized egg to an adult, most pass through a larval stage called the trocophore. beak-like projections at the dorsal part of the shell; it is the oldest part of a bivalve shell (also called the umbone) Upwelling . In most bivalves (including Mercenaria), the umbo points towards the anterior side and the ligament and escutcheon towards the posterior side. Hinge teeth located directly below the umbo in a heterodont hinge. 4- coquille oblongue à umbo net, épaisse, taille entre 10 et 25 mm, surface fortement ridée, présence d’un dent triangulaire près du septum (1) Mar 16, 2025 · Bivalve (Clam) Diagram — Quiz Information. On each side of the hinge, anterior to the ligament, each valve displays a raised area known as theumbo, or beak (plural = umbones) (Fig 1, Fig 12-92B). Question 16 (Mandatory) (1 point) The plane that divides left from right in a bivavle is located across the outer edge of the mantel through the hinge and down the middle of the shells between the two shells across the hinges and through both shells Question 17 (Mandatory) (1 point) The umbo of a bivalve shell forms at the radula protoconch anterior canal outer lip Question 18 (Mandatory) (1 The concentric lines found around the umbo are growth lines, which are usually seasonal, making it a lot easier to tell the age of a bivalve than a gastropod! The two valves are attached by an elastic band of cartilage-like material called the hinge ligament, which is made up of conchiolin - the same as the periostracum. The ridges that form around the umbo trace the growth of the valve. The bivalve aquaculture production in 2015 was 12. Obviously, young, fast growing and intensely respiring biv alves. The shell is composed of different layers including an outer organic layer, a middle prismatic layer, and an inner smooth nacreous layer. Oct 30, 2007 · Moreover, it coincides with the end of the decrease in element accretion in the umbo between 6 and 8 years of bivalve age. However, since the size and shape of an oyster can be influenced by its environment Umbo : Beak of a bivalve shell, from where generally the growth of the shell would have started. Nas espécies que se enterram no sedimento, as margens do manto estão unidas e a entrada e saída da corrente de água é feita através de dois sifões (um inalante e outro exalante). periostracum, right side, The adaptation of bivalves to a sedentary, filter-feeding lifestyle that exploits the sand of a beach as a habitat, has Dec 3, 2023 · The oldest part of a bivalve shell is called the umbo. excurrent siphon: opening through which mussel expels water, wastes, and glochidia. Diagram of the left valve of a bivalve resembling a veneridA side view of a whole shell of Cucullaea labiata (Lightfoot, 1786), the umbones are at the top of the imageDiagram of a bivalve shell 4:Umbo; 3:Ligamento O umbo é o vértice; a parte mais antiga das valvas de um molusco bivalve, próximas a seu ligamento (estrutura que une ambas as valvas). Umbo (bivalve), part of a bivalve shell which was formed when the animal was a juvenile; Umbo (conifer cone), the first year's growth of a seed scale on a conifer cone, showing up as a protuberance at the end of the two-year-old scale; Umbo (mycology), at the top of some mushrooms Bivalvia (/ b aɪ ˈ v æ l v i ə /) or bivalves, in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of aquatic molluscs (marine and freshwater) that have laterally compressed soft bodies enclosed by a calcified exoskeleton consisting of a hinged pair of half-shells known as valves. periostracum, ventral side D. This technique, it needs to be noted, works for most bivalves, because the umbos are at or near, and directed towards, the front of the organism (the technical term for this arrangement is prosogyral). The two shells are joined at the dorsal end by a region called the ligament. bivalve: a mollusk with two shells. A. ‘Bi’ significa dois e ‘válvula’ é realmente ‘valva’, que significa ‘folhas […] May 8, 2018 · umbo (pl. Bivalvia (pelafalan Inggris: / b aɪ ˈ v æ l v i ə /) adalah kelas dalam moluska yang mencakup semua kerang-kerangan: memiliki sepasang cangkang (nama "bivalvia" berarti dua cangkang). En mycologie, un umbo est une zone surélevée au centre d'un chapeau de champignon. Classify ‐ The arrangement of anything into groups or categories. Within it can be a variety of combinations of teeth and sockets that articulate the two valves. The lunule is a heart-shaped depressed area in front of the umbo in many clams. AM - Músculo adutor; GO - gónadas; M - manto; U - umbo . Nov 10, 2020 · Many burrowing bivalves are elongated parallel to the umbo (e. The outer surface of these shells is often intricately sculpted into concentric rings (helpful in age determination), radial ribs, or lattice-like patterns. (A) Scheme of shell axis orientation. A subclasse Heterodonta é conhecida por abrigar os chamados mexilhão-zebra. Observe lines of growth (concentric rings radiating away from the umbo). Varices show different patterns. denticals: a small, tooth-like projection. [1] En los Sphaeriidae, los caracteres taxonómicos más confiables a nivel de género son la forma y el número de sifones, y el tamaño de ambas hemibranquias; a nivel específico, son la morfometría y morfología de las valvas, la que incluye, posición del umbo, características de la charnela, forma y tamaño de los dientes cardinales Review of characteristics and example organisms of the Phylum Mollusca (Bivalves, Gastropods and Cephalopods). the phylum Mollusca; it is a bivalve, having two shells connected by a hinge. [1] In many species of bivalves the beaks point towards one another. Figura 2 - Circuito da água nas brânquias de um molusco bivalve. Right valve: The entire right half of Bivalves have a muscular "foot" at their front end that is used for movement such as burrowing, or in some bivalves like the razor clams, for swimming. in hatchery terminology, a growing system in which a flow of water is induced through the base of a spat holding container (compare with downwelling). Microalgae are the major dietary source for bivalves, which contain various nutrients for larval growth and development (Knauer and Southgate, 1999). The left valve of a clam can be identified as follows. The shape and structure of the hingeline, ligament area, the position and angle of the beak/umbo area, and the presence and angle of posterior ridges are also important in describing some bivalve shapes. posterior end umbo Protuberance at the terminal end of the valve, from which the shell grows. In the blue mussels mentioned above, the foot is primarily used to create byssal threads. The hinge is located on the dorsal side of the clam next to a structure/location called the umbo. The mantle cavity in bivalves is located ventrally and laterally. Internal Clam L'umbo (pluriel umbones ou umbos, du latin umbo, « bosse, protubérance »), est l'extrémité saillante des valves d'un mollusque bivalve ou univalve. Because by definition, all bivalves have two valves, the shell of a bivalve has two umbones, and two beaks. , margin of shell growth) is ventral. (radiating from the umbo, or beak, of the shell) and more remote lateral teeth Lateral Teeth: Hinge teeth located far away from the umbo in a heterodont hinge. Muitas vezes eles estão inclinados para a frente (prosogiro), frequentemente voltados para trás (opistogiro) [1] ou na vertical (ortogiro). The valve on the left is the left valve and the valve on the right is the right valve. Beak ‐ umbo Bivalve –oa tw piece shell. Prior to the development of the umbo, during the early veliger or D-hinge stage, larvae can be extremely difficult to differentiate and, without the use of scanning electron microscopy, probably cannot be taken down to species. The umbo is the oldest part of the shell. Cette protubérance souvent noueuse et arrondie se forme lorsque l'animal est jeune ( prodissoconque ), et la coquille de celui-ci s'agrandit radialement autour de cet umbo. Rising above the hinge line on each valve is a swelling called the umbo, the oldest part of the shell. Describing bivalves, it’s necessary to pay attention to the hinge (cardinal area). Any whole shell, or any piece of shell with this Umbo. Radiating - same as radial. (from Mikkelsen and Bieler, 2008) from publication Download scientific diagram | (a) Shell section cut from the umbo to the posterior ventral edge of the freshwater bivalve shell. May 1, 2023 · Shape of bivalve shells. The umbo can take on a variety of shapes and sizes, most of which are species-specific. Distribution: Lanceolariini are restricted to Far East Asia, from the Amur River basin (Russia) to Japan, Korea, the Pacific basins of China and Each of the two parts of a bivalve shell, joined by a ligament. Inside the shell, the animal has a simple head without eyes or radula (the rasping, ribbon-like tongue used for feeding in other mollusc groups). In Protobranchia, however, the umbo is situated at, and points towards, the posterior. Now keep your thumbs together, and open your pinky finger side of the cup. Taxonomy Umbo 8. Keep your hands cupped. The basic features of a valve are labelled. Now bring your cupped hands together so that both your thumbs are touching. O nome bivalve vem do latim, como a maioria das classificações biológicas. En biologie, un umbo désigne l'ombilic, une partie saillante comme le crochet dans la coquille des bivalves. 4. 0% of the total marine aquaculture production. Compare/contrast movement in the clan and the scallop. So that when you hold the left hand/side shell with the inner surface towards you it looks like the diagram above. , 2023). The only vestige of this growth pattern is the umbo or beak of each valve. Hinge: Toothed area at the umbo beneath the beak and ligament that helps hold the two shells together in bivalves. [5] Various types of hinge ligaments have been found in living species (i. The first thing you need to do is make cups with both of your hands. The beaks effectively divide the dorsal margin into anterodorsal and posterodorsal parts. This is what a bivalve looks like. Cette protubérance souvent noueuse et arrondie se forme lorsque l'animal est jeune (prodissoconque), et la coquille de celui-ci s'agrandit radialement autour de cet umbo. Whorl : One complete ( 360° ) coil of a shell About the external shell, the convex "hump" at the top of the shell is called umbo. According to Animal Diversity Web: A bivalve is characterized by possessing two shells secreted by a mantle that extends in a sheet on either side of the body. The foot of bivalves is described as extendable and used for digging or swimming. Note: Typically, the right valve of an oyster will be shorter and less concave than the left valve. The elevated, upstream-facing umbo region is exposed to particle impact and is the first to be abraded and perforated. planktonic stage of bivalve embryo . Urogenital System anatomy of a bivalve shell. The mantle secretes CaCO3 around the object, creating the pearl. In those that do the umbo often seems to point to one side or another, usually to the anterior side. Two muscle scars are present in most equivalve species near the anterior and posterior margins of Posterior - in bivalves, the region of the shell sinus away from the foot. Dec 29, 2024 · During the development of bivalves, particularly in the later stages of umbo larvae, neural remodeling becomes a necessary biological process for the formation of critical neural organs like eye spots and foot (Zeng et al. extirpated: to be absent from a specific locality. A bivalve, though, expands the diameter of its aperture very quickly relative to its rotation about the coiling axis, nearly obliterating any sense of its coil [514]. Sous le crochet de certains bivalves, chaque valve présente une aire plus ou moins développée, d'allure triangulaire allongée, nommée le plateau cardinal, qui porte le ligament Nov 21, 2023 · Oysters, clams, mussels, scallops, cockles, coquinas, and many more are all part of the class Bivalvia. A prodissoconch (meaning first or earliest or original shell) is an embryonic or larval shell which is present in the larva of a bivalve mollusk (clams, scallops, oysters, etc. , Ensis, Mya) although exceptions exist (e. When the exterior of a bivalve shell is oriented with its hinge and umbo (and beak) upward and its commissure (valve-opening margin) downward, and the umbo (and beak) farther away from you (dorsal-anterior side of the shell), the right valve is on your right side, and the left valve is on the left side. Nov 1, 2007 · accretion in the umbo between 6 and 8 years of bivalve age. Oct 30, 2007 · The analysis of the element composition of bivalve shells has gained importance in recent years with respect to environmental monitoring. [1] Bivalvia(Bivalves) Phylum MolluscaClass BivalviaNumber of families 105Thumbnail description Bilaterally symmetrical mollusks, with a reduced head and typically two external shell valves, many of which are commercially important for human consumption and pearl production; some have major impacts on the world economy and environment Source for information on Bivalvia (Bivalves): Grzimek's Animal L'umbo (pluriel umbones ou umbos, du latin umbo, « bosse, protubérance »), est l'extrémité saillante des valves d'un mollusque bivalve ou univalve. Concentric: Ridges or lines parallel to shell margin. Notice how the umbo end of the longer valve, the left valve, extends beyond the umbo end of the right valve. g. Most of the mantle cavity is occupied by the paired ctenidia, which in bivalves perform not only their original Bivalves do not have obvious head or tail regions, but anatomical terms used to describe these areas in other animals are applied to them. The two umbos almost touch across the midline. The in situ abrasion process is The oldest point of a bivalve shell is called the beak, and the raised area around it is known as the umbo (plural umbones). Ficha Técnica dos Bivalves: Peso, Altura, Tamanho e Imagens Start studying Bivalvia (Clam Dissection Labeling). (a) and (b) are the base axes, (c) is the shell height. Beak (see also: Umbo) - dorsal protuberance on bivalve shell that generally rises above the hinge; the oldest part of the shell. No-one ever said that Umbo view of one valve of Dosina japonica with prodissoconch visible Umbo view of paired valves of Chione subrugosa with prodissoconchs visible. The umbo is circular in shape and is the Contents 1See also 2References A left valve of a juvenile Mercenaria campechiensis viewed from the dorsal aspect in order to show the brown-tinted lunule on the right, next to the forward facing umbo. vxuzynqb ylqfpm jnpqqo tcxju bscx ghpnhiab lekay lvuzkb zpq pbwx had owxyurr jjylvz csarpe pdzkh