There is no such thing as a symmetric organism. Plants have roots at the bottom and leaves at the top, while animals generally have a mouth at one end and an arsehole at the other. Even unicellular organisms universally show some kind of polarity. All of these are asymmetries!

I think you need to define the question a bit better before you can get meaningful answers. Are you looking for examples where the majority of the body plan follows a symmetric organisation (e.g. bilaterality in vertebrates) but where the symmetry is locally broken? Or are you after a more general question of how axes become polarised - what makes a head different from a tail, how does the body "choose" an axis during development, etc.?

I suggest the reference: LANCELOT R., FAYE B., LESCOURRET F., 1997. Factors affecting the distribution of clinical mastitis among udder quarters in french dairy cows. Vet. Res., 28, 45-53

If you are interested in examples from zoology one of the most pronounced assymetries you can find is in the fiddler crab (genus Uca).

You can also try with

Huber, B. A., B. J. Sinclair, et al. (2007). "The evolution of asymmetric genitalia in spiders and insects." Biological Reviews 82(4): 647-698.

or more general

Van Dongen, S. (2006). "Fluctuating asymmetry and developmental instability in evolutionary biology: past, present and future." Journal of Evolutionary Biology 19(6): 1727-1743.

or again more special

Vogt, G., C. S. Wirkner, et al. (2009). "Symmetry variation in the heart-descending artery system of the parthenogenetic marbled crayfish." Journal of Morphology 270(2): 221-226.

Greetings

We can see structural assymetry in lung in mammals, for instance... In doubt about functional assymetry?

May I know what for you are looking for structural and funcional asymmetry? Any specific reason, or a just curiosity.

This is because asymmetry is an important aspect of biology that is common and all purvasive at individual and at group level. It has very serious implications in evolutionary biology - the simple fact that severe asymmetry does affect the survival and is therefore under selection pressure.

If one wants to have an idea of structural and functional asymmetry there are enough material available on the subject and can browse through internet.

On the research front, there are number of issues concerning studies on asymmetry both structural and functional and these issues vary from chemestry, botany, pschology, physics, statistic, mathematics and anthropology. There are theories based on asymmetry both in biology, physics, chemistry, economics, information theory and mathematics and statistical field that deal with asymmetry -- theories, how to estimate, how to measure etc. and the implications e.g.

In nature there are no completely identical things or individuals, almost everybody is asymmetrical either in funcion and in structure, however certain purturbations inherent in biological development that lead to a certain amount asymmetry that one can observe and study which are in terms of structural and functionally insignificatnt and may not lead to survival or health of the individual, a certain threshhold of asymmetry does cause serious problems leading to disease and may have debilitating or inability or maladjustment etc.

Certainly I am not listing infinite examples of structural or funcitonal asymmetry, that one can always get it from internet browsing, but trying to open up a scope and importance of asymmetry in various fields of sciences that deal asymmetry, eg., fluctuating asymmetry etc. there are tons of materials;

An example of functional assymetry among photosynthetic organisms is the light gradients generated in the photosynthetic structures (tissue or canopies). Chloroplasts or leaves more exposed to higher light levels are acclimated to high light conditions and deeper in the tissue, they acclimate to low light levels. This heterogeneous light environments are generated by plant complexity (organism organization) and have to adjust to the environmental changes with more or less success (efficiency in the use of the resources and plant productivity). Basically, this heterogeneity in the internal light fields allow to reduce photodamage and the dependence of plant physiology on the large temporal changes in light availability (more robustness despite the potential reduction in plant growth).

compound L-alanine amino acid which found in cell wall membere in bacteria , is transfer to D-alanine in some bacteria that means resistance to antibiotics, and there are many compounds in carbihydride also has assymmetris

There are a lot of structural and pathological-functional asymetry in animals, examples are in cows right lung is bigger than left lung, pregnancy in cows is more common in right horn of the uterus, inguinal/scrotal herias are more common on the left in bulls, abnormal displacement of the abomasum (the true stomach in ruminants) is more common to the left.

I am very pleased with the answers received so far. Well, there is also the asymmetry between head and tail also, between the inside and the outside of an organism, the time irreversibility, left and right asymmetry , and so on. But , I found some of the specific answers provided here, especially anatomical ones, fascinating. I was not thinking of the pathological asymmetries. The asymmetry of the Y male chromosome is also an interesting one. The asymmetry of up and down imposed on plants (and not only) by gravity is also relevant here. Beyond these, there is a fundamental asymmetry in the complex organization of all organisms that renders them incompletely 'simulable'

by digital computers. A kind of asymmetry that mathematicians call ``noncommutativity". To be more explicit, the complexity of organisms emerges as a result of an asymmetric process of emergence which can be represented in a dynamic encoding diagram that does not commute with any digital computer models.

In nematodes of the family Spirocercidae you might find asymmetrical cervical papillae and caudal wings

Several of my papers on lizard/Sphenodon might be useful to you:

Seligmann H. 2011. Left-handed Sphenodons grow more slowly. Advances in Medicine and Biology 24, chapter 4, 185-206, Berhardt LV (ed).

Seligmann H., Moravec J., Werner Y.L. 2008. Morphological, functional and evolutionary aspects of tail autotomy and regeneration in the “living fossil” Sphenodon (Reptilia: Rhynchocephalia). Biological Journal of the Linnean Society, 93: 721-743.

Seligmann, H., Beiles, A., Werner, Y.L. 2003. More injuries in left-footed lizards. Journal of Zoology, London, 260: 129-144.

Seligmann, H., Beiles, A., Werner, Y.L. 2003. Avoiding injury or adapting to survive injury? Two coexisting strategies in lizards. Biological Journal of the Linnean Society, 78: 307-324.

Seligmann, H. 2002. Behavioural and morphological asymmetries in hindlimbs of Hoplodactylus duvaucelii (Lacertilia: Gekkonomorpha: Gekkota: Diplodactylinae). Laterality, 7: 277-283.

Seligmann, H. 2000. Evolution and ecology of developmental processes and of the resulting morphology: directional asymmetry in hindlimbs of Agamidae and Lacertidae (Reptilia: Lacertilia). Biological Journal of the Linnean Society, 69: 461-481

Seligmann, H. 1998. Evidence that minor directional asymmetry is functional in lizard hindlimbs. Journal of Zoology, London, 248: 205-208.

In addition, I have a number of publications describing associations between the accuracy of different molecular processes and morphological asymmetries:

Seligmann H. 2011. Mutation patterns due to converging mitochondrial replication and transcription increase lifespan, and cause growth rate-longevity tradeoffs. DNA Replication-Current Advances, Seligmann H. (ed.), InTech, book chapter 6, 151-180.

Seligmann H. 2011. Error compensation of tRNA misacylation by codon-anticodon mismatch prevents translational amino acid misinsertion. Computational Biology and Chemistry 35: 81-95.

Seligmann H. 2010. The ambush hypothesis at the whole organism level: Off frame, ‘hidden’ stops in vertebrate mitochondrial genes increase developmental stability. Computational Biology and Chemistry 34: 80-85.

Seligmann H. 2006. Error propagation across levels of organization: from chemical stability of ribosomal RNA to developmental stability. Journal of Theoretical Biology, 242: 69-80.

Seligmann H., Krishnan, N.M. 2006. Mitochondrial replication origin stability and propensity of adjacent tRNA genes to form putative replication origins increase developmental stability in lizards. Journal of Experimental Zoology B, 306B: 433-449.

There is also from other authors:

Razzetti E, Faiman R, Werner YL 2007 Directional asymmetry and correlation of tail injury with left-side dominance occur in Serpentes (Sauropsida). Zoomorphology 126, 31-43

Werner YL, Rathenstein D, Sivan N 1991 Directional asymmetry in reptiles (Sauria: Gekkonidae: Ptyodactylus) and its possible evolutionary role, with implications for biometrical methodology. Journal of Zoology 225, 647-658.

Last, there is the issue of asymmetry in DNA (see wikipedia: http://en.wikipedia.org/wiki/Directionality_(molecular_biology). It has been believed since very long that DNA is only polymerized and read in the 5'->3' direction. This has been found incorrect, though overall, the directional asymmetry remains, as the usual 5'->3' direction remains preponderant:

Seligmann H. 2012. Overlapping genes coded in the 3'-to-5'-direction in mitochondrial genes and 3'-to-5' polymerization of non-complementary RNA by an 'invertase'. Journal of Theoretical Biology, 318, 38-52.

Jackman JE, Gott JM, Gray MW 2012 Doing it in reverse: 3'-to-5' polymerization by the Thg1 superfamily. RNA 18, 886-899.

Note that each of the 2 latter references reports different phenomena. The last reports that regular RNA is produced by a process with opposite direction to the usual process. The fits shows that RNA that is produced by an unknown process is 3'-to-5' RNA. Hence the first shows opposite direction for the product, the former only for the process (polymerization), but not the product (RNA).

The human brain has both. Language centers are typically lateralized to the left hemisphere. Right handedness in ~92% of the population is a consequence of this.

During my postdoc time my professor in biochemistry defined a living cell by the fact that concentration gradients across lipid membranes (ion, sugars, protons, etc.) are intact. This is a very interesting view that asymmetry of transport and energy processes across cell membranes as the definition for life.

they are plenty ... open books and eyes, should I say ...

asymmetry of flatfishes (soles, turbots) concerning both external and internal organs, shape of the liver, differential size of lungs... shape of the shells of gasteropods ... abdomen of hermmit crabs ...and so on ...

Comparative anatomy of vertebrates - the arch of aorta in birds and in mammals: In birds aorta ascendens turns to the right. In mammals aorta ascendens turns to the left forming aorta descendens in both of classes. It's a spectacular asymmetric evolution.

from, as mentioned, blood vessels organisation in Vertebrates, to visceral torsion of gasteropods and asymmetry in the flying feathers ... and so on ...

we are not here for lectures on animals diversity ... are we ? data exist ... almost everywhere in libraries and on the Internet !!! curiosity and gathering data are the basis of the job, aren't they ?

The flounder's twisted head is a fine example.

Many crabs are seen to have front claws substantially unequal in size.

Males of the earwig family Anisolabididae have one forceps tong curved in more than the other.

@Christopher Engeland. I read somewhere that marks on the earliest clay pots indicated that the potters were equally left and right handed. Do you think this means that the move to right handedness and the increase in language use have gone hand-in-hand (no pun intended). And is there any evidence that those people who are left handed have less well developed language skills?

Dear Vasulu,

I am Asit here. You may recall me as one of your colleagues in ISI. I agree that Structural or functional asymmetry in organisms is extremely important. You will observe it within an individual organism, within a population as well. For example in developmental biology when a single fertilized cell starts forming pattern with a number of events simultaneously and sequentially. All those events generate patterns those are different from each other although it forms with the same process from same origin. This happens due to multiple unstable steady states in the process- each of those unstable steady states creates bifurcation and bifurcating solutions creates the asymmetry. From system dynamical point of view biochemical reaction parameters playing an important role in it. These parameters are subject to influence by external small amplitude disturbances during its developmental processes that creates the perturbation within the selective parameters - hence creates the bifurcations.

Hope you are doing well. I am fine working in US as Associate Professor. Working on Tissue Engineering of Articular Cartilage.

Regards.

Asit

I appreciate the numerous examples already received. There is now a related question remaining to be asked. Before proceeding with this new but related question , I should like to make the point that often a symmetry is broken, at least in part , giving rise to multiple, local symmetries. Asit' s examples from biological development stages are of this kind. Whereas in crystallography, as for example in the case of symmetry classification of atomic crystal groups there are only 234 possible classes of symmetry space-groups (that are precisely defined mathematically in terms of symmetry operations such as reflections and rotations, etc.), in material science, nanoscience (e.g. molecular crystals and quasi-crystals) things may appear not be as neatly and completely defined even when the local symmetries are precise and are well-defined because mathematical groups become then insufficient to classify the latter structures that possess broken symmetry, or only local symmetries thereof.

The related question is that of the appropriate mathematical structure(s) that represent local symmetries and link these to a global symmetry iff present.

Vasulu, the reason is quite simple but the answers are complex in nature:

In simple physical systems such as atomic crystal lattices there is a classification of structures based on mathematical groups because of the extremely high level of symmetry present in such 'simple' systems. On the other hand, once the symmetry becomes broken, or one has an asymmetric structure-- which is not obviously quite the same thing-- one still needs some adequate means for classifying such asymmetric structures. also the reasons for the presence of the asymmetry are important for understanding the complex systems that may appear globally to lack symmetry. In physics itself, non-Abelian gauge groups were introduced, and then unrelated to the non-commutative gauge field structures, Stephen Hawking claims that at the origin of the Universe and the Big-bang lies a basic asymmetry of Nature--"because Nature is imperfect"-says Steve-- thus proposing to exclude any Creator from the explanation of the origins of our Universe. Yet another prominent mathematician, Alan Connes proposed a noncommutative `space' theory based on a mathematical Noncommutative Geometry that he claimed to be consistent with the Standard Model-SUSY in modern physics. So, it may be that classifying biological processes and structures one also needs Non-Abelian Mathematics , but not necessarily Noncommutative Geometry `a la Alan Connes, but perhaps more general mathematics such as Nonabelian (non-Abelian) Algebraic Topology and higher Dimensional Algebra (HDA; recently introduced and developed prominently by Ronald Brown in the Department of Mathematics and Computer Science at Bangor University in Wales, UK). These are usually higher dimensional structures (HDS) that accommodate quite well asymmetry in hierarchical structures such as those present in organisms and also in societies (although the HDS is quite different in the two cases).

The asymmetry I am familiar with pertains to the self-renewal of stem cells. Stem cells invariably divide asymmetrically, of necessity, and give rise to a mother cell which is a replica of the original and a daughter cell which is different from the original. In other words, asymmetric divisions give rise to one copy of the mother cell and a novel cell type. Such divisions are called self-renewal. Self-renewal is a hallmark of stem cells. The daughter cell is irreversibly committed to differentiation. Differentiation is precisely balanced by renewal of the stem cell population. Stem cells can also divide symmetrically to increase their numbers. These 2 types of divisions are responsible for never running out of stem cell reserves in organs and yet having enough committed cells to continue with the programme of differentiation in organs. It applies to all tissues. During intrinsic asymmetric divisions, the macromolecules are localized asymmetrically to one half of the cell. During cytokinesis, the stem cell divides in two such that the mother and daughter cells differentially inherit asymmetrically localized cell proteins/transcripts. The unequal inheritance thus produces two cell types with different fates. The daughter cell then divides symmetrically to produce progenitor cells which give rise to adult stem cells. Whereas the mother cells are toti/pluripotent the daughter cells are multi/unipotent which eventually give rise to differentiated cells like sperm in testes, neurons in the brain. However, as for the left handed individuals, has the language centre shifted to the right hemispheres? I have always been told never to force a left hander to write with the right hand lest they begin to stammer. manjeet sharma

Symmetry is key for esthetics in dentistry. the appearance and size/shape proportion of teeth from one side should be exactly the same to the opposite in order to obtain a harmonious smile and balance the matigatory stresses in the craniofacial structure. If this is now observed, patients often suffers from neck and headaches, difficulties to open the mouth and feed and lower self-esteem.

Some owls have ears that are placed asymmetrically, which helps them to triangulate sound and locate its source.

It was recently reported that miR 941 gene is unique to humans and is absent in apes. Moreover, it appears to be involved in the development of human brain. It is thought to play a role in the development of language. In the context of asymmetry, is it possible that in the right handed individuals, the expression of miR 941 would have shifted from the left to right hemispheres in the left handed individuals? And would there be more of such genes which could be expressed asymmetrically in the different sub-regions of the brain during development and aid in the regional specialization for different activities? manjeet sharma

This answer is more to Manjeet than to the initiator of this threat. I do know that among 'true' (homozygotic) twins, the probability that one is left- and the other righthander is about twice the probability of getting in a regular singlet birth a left hander. Among the two, the left hander is almost half a kg (on average) lighter than the right hander. You can find relevant references to this in my paper '" Seligmann H. 2011. Left-handed Sphenodons grow more slowly. Advances in Medicine and Biology 24, chapter 4, 185-206, Berhardt LV (ed)." but I do know there has been made more work about this and there might be also more recent publications/breakthrough.

The asymmetry in terms of frequencies of D versus L amino acids also exists, though at much weaker levels, when looking at amino acids found in meteorites, hence it is not only a byproduct of special conditions on earth and in our life system. Though i read this in an ancient Nature or Science paper, I could not refer you to it.

The two cerebral hemispheres are viewed as mirror images but are functionally different, areawise. Greats like Einstein have subtle differences in a particular brain region inspite of the fact that his brain had a brain weightcomparable to normal humans. Homozugous twins have been reported to be different in many cases to my knowledge (though I have not read your book). Infact, I worked on inbred mouse and rat strains during my doctorate and can tell you that although mice within a strain look and behave identical, they have functional differences in neurotransmission. Apparently, this is inspit of the fact that their genes have been fixed 99.9% during inbreeding. I wonder if left and right handed individuals have a lot of functional differences in terms of gene expression in various brain areas specialized for different functions. As for amino acids, at some point in Evolution, higher forms of life underwent selective pressure and shifted to laevo rotatory/L amino acids whereas the dextro rotatory/D amino acids formed the proteins of lower organisms. Interchange the two mirror images L/D forms and that will lead to havoc. I wonder whether L forms offered any evolutionary advantage for this shift to have occurred.

All of the brain centres and glands are symetric , the only one is pineal glad...so important...yes...seat of the soul ???...yes, yes, yes

Heart is not placed in thoracic cavity with equal distribution in hemithoraces, nor are the functional chambers, atria and ventricles, identical in shape or function. Mammalian livers generally have an unequal distribution of lobes in the abdominal cavity and an asymmetrically placed gall bladder.

See this:

http://www.amazon.com/The-Language-Shape-Curvature-Condensed/dp/0444815384

Many crustaceans have indepedently evolved heterochely, different claw sizes, which serve diverse function as different as male display (e.g. fiddler crabs in the Genus Uca) or access to diverse food resources (e.g., cutting vs. crushing claws of the American Lobster Homarus americanus that evolve as a development functional response to early food type availability).

Some structural and/or functional asymmetry examples: human liver; human heart, stomach, actually most of the gastro-intestinal system. Many crustaceans have structural asymmetry (e.g. one bigger claw) for functional purposes, oh I see now this was mentioned in the previous responce. Some ocean bottom dwellers have acquired structural asymmetry, i.e. symmetrical upon hatching, but becoming asymmetrical adults.

Dr Seligmann, would you care to share your thoughts on the evolutionary strategy of shifting to D amino acids in lower organisms to L amino acids in higher organisms? Do you think it is likely that this shift was intended to cause the development of the current immune system? Our antiboodies are all proteins with L amino acids wheras the invaders/ microorganisms have the D forms. Would the shift be useful in recognising the alien D form proteins? Just a thought.

There is an open acess paper on asymmetry in plants and mussels from Chernobyl:

Yavnyuk A. A., Efremova N. N., Protsenko O. N., Gudkov D. I., Nazarov A. B. Fluctuating asymmetry of zebra mussel (Dreissena polymorpha Pall.) and floating pondweed (Potamogeton natans L.) in water bodies within the Chernobyl accident Exclusion Zone. Radioprotection, 2009, 44(5): 475-479.

Check out the vertebrate habenula brain nucleus. Fishes and frogs have a marked asymmetric volume. Check out Bianco and Wilson, Phil Trans R Soc B (2009), 364:1005-20.

Yes I agree to Vasulu TS , this topic is very broad.....what type and in which particular organism/organ/ aspect you are interested in is very relevant to get an appropriate response. I worked on plants...in crops like mungbeans there is asymmetry between the two cotyledons .....seemed to be related to genetic background...

Dr Sharma,

I am not aware that 'lower' organisms use usually D amino acids. As far as I know, organisms use all L amino acids, and D sugars and D nucleotides.

There are exceptions of using L sugars, such as cellulose, and this is indeed along your idea of protection. Plants are less attacked by bacteria/fungi because the L sugar cellulose is very difficult to break down. Similar types of situations occur for other organisms or molecules, but they are overall rare. I do think they tend to be restricted to 'lower' organisms (if you mean by that fungi, plants, bacteria) and are being interpreted as protections. But overall, also these organisms use for their usual metabolism proteins and sugars with the same chirality as 'higher' organisms. If this is incorrect, please give me the source for this, I am very interested on the matter.

The skulls in Odontocete whales - (I'm not an authority) but the bones where the echo-location tissue sit in front of are twisted - apparently to distinguish left from right.

^ Pollegioni L, Piubelli L, Sacchi S, Pilone MS, Molla G (June 2007). "Physiological functions of D-amino acid oxidases: from yeast to humans". Cell. Mol. Life Sci. 64 (11): 1373–94. doi:10.1007/s00018-007-6558-4. PMID 17396222.

D-aspartic acid occurs naturally within all animals, but in much lower amounts compared to L-aspartic acid. D-aspartic acid is known to accumulate in the pituitary gland, pineal gland and testes, and is involved in hormone production, according to the “Textbook of Functional Medicine.” More specifically, it stimulates the release of sex hormones from the pituitary gland and testosterone from the testes. Consequently, D-aspartic acid has become a popular supplement among bodybuilders, other serious athletes and elderly men who have low-circulating levels of testosterone.

Read more: http://www.livestrong.com/article/557557-the-differences-between-l-aspartic-acid-d-aspartic-acid/#ixzz2F2gL5Sxu

Broca's area (center of speach) is located in the left brain hemisphere; in people that use predominantly the right hand, the left hemisphere is more complex than the right one (and vice-versa for the left-handed); in organisms with bilateral symmetry, this symmetry is not a perfect, geometrical one; there is always an "asymmetry in the symmetry', in that one of the parts is bigger/smaller, and there is also a slight difference in functioning (we see better with one eye, we hear better with one ear etc.).

see google search for "asymmetry asymmetric OR asymmetric OR structure OR biology"

Norberg RA. Occurrence and independent evolution of bilateral

ear asymmetry in owls and implications on owl taxonomy

Dr Seligmann, These reports are from literature.

The asymmetrical genitalia of the male Corixidae (a family of aquatic insects) provides a good example.

TESTES ASYMMETRY IN MANY BIRD SPECIES (BIRKHEAD ET AL., 1998. Proc. R. Soc. Lond. B (1998) 265, 1185^1189).

FIDDLER CRABS: http://www.science.uva.nl/library/pdf/RosenbergThesis.pdf

THE MALE STRIDULATORY APPARATUS OF PSEUDOPHYLLINAE KATYDIDS (TETTIGONIIDAE, ORTHOPTERA). Montealegre Z., F. & Morris, G.K. 1999. Songs and systematics of some Tettigoniidae from Colombia and Ecuador I. Pseudophyllinae (Orthoptera). Journal of Orthoptera Research, 8: 163-236.

Morris, G.K., Klimas, D.E. & Nickle, D.A. 1988. Acoustic signals and systematics of false-leaf katydids from Ecuador (Orthoptera,Tettigoniidae, Pseudophyllinae). Transactions of the American Entomological Society (1890-), 114: 215-263.

These are some quite spectacular examples

Accurately measure the toe to heel length of your feet.

There is quite a vast literature in ecology & biology in general related to anti-symetry (as the one in the violinist crabs), directional asymmetry (as human heart) and fluctuating asymmetry (random nondirectional deviations from perfect symmetry, proposed as a useful indicator of environmental stress) Good review papers in this line could be for example, Palmer AR, C Strobeck 1986 Fluctuating asymmetry: measurements, analysis, patterns. Annu Rev Ecol Syst 17:391–421. or Van Valen L 1962 A study of fluctuating asymmetry. Evolution 16: 125–142.

All organs that are present in only one copy: stomach, l & S intestines, heart, etc.

See attachment on brain laterality and laterality in body functions

Hi,

A good example is Vitamin B6 (Pyridoxal phosphate) a cofactor in many reactions of amino acid metabolism, including transamination, deamination, and decarboxylation. PLP also is necessary for the enzymatic reaction governing the release of glucose from glycogen.

Terence Hale

A few different examples: Epithelial cell polarity, organization and structure, yeast bud-site selection and growth, organismal morphogenesis during development, directional movement and migration of cells e.g. during morphogenesis, chemotaxis or metastasis of cancer cells... the examples are endless.

Find an example of lateralization in antennal contacts in ants:

http://www.reznikova.net/Publications.html

E. Frasnelli, I. Iakovlev, and Zh. Reznikova, 2012. Asymmetry in antennal contacts during trophallaxis in ants.

Behavioural Brain Research, 232, 1, pp. 7 - 12.

Female reproductive asymmetry in bats is perhaps a good example of both permanent and temporary structural and functional asymmetry in mammals. Please see this link to a reference with drawings to illustrate the uterine asymmetry: http://www.reproduction-online.org/content/56/1/345.short. The title is Reproductive Asymmetry and Unilateral Pregnancy in Chirpotera, Wimsatt, W.A. J. Reprod. Fertil. (1979) 56:345-357. Note that temporary unterine asymmetry has been described in the mega-chiropetra suborder. Hope this is of interest.

One of the best examples for asymmetry in biology of mammals is tissues of liver, lungs, stomach and heart.

Asymmetric divisions (stem cells, self renewing and differentiation, development) ...si multe altele

In crickets and katydids where the fore-wings overlap to create a stridulation organ the top and bottom of the wing pair are necessarily by design asymmetric to allow for opposing stridulation structures.

A very humble example, but a very robust one, is the extreme asymmetry of the ovaries and oviduct of the domestic chicken: only the right survive.

Of course, it's the left ovary/oviduct that is present in the adult female hen, not the right...

All cells of any organism has an asymmetric electric charge and a asymmetric distribution of ions, is the basis of all physiological functions.

An asymmetry exists too in the ovary/oviducts of many sharks

Amoeba, Sponges etc., show asymmetric structure

Depending on how you define asymmetry, you can call it a discrepancy (perhaps noise), i.e. the non zero result of a subtraction. A difference. Such discrepancies are at the heart of all fundamental living processes such as action potentials, heart rate variability, or in psychology, the trigger of fear, curiosity or envy.

What is defined as auto-organization (see H Atlan for an example) supposes a bias in symmetry triggering an adaptive compensation.

In Occident, we discuss such discrepancies as differences, but following the chinese approach (François Jullien : L'écart et l'entre) using the word gap would help overcoming difficulties such as identity or differences. In general.

I am not happy with the inclusion of amoeba and sponges in the asymmetry group since without further specification it allows for including everything that has no symmetry at some level. The asymmetry classification should be reserved for situations where there is an established symmetry that is then departed from in some described way. In the case of a sponge there might be a circular or spherical shape but no rotation or reflection observable to bring it into registry with another symmetry, so how can you define anything of such shape as an asymmetry. We must be specific in the symmetry and then the asymmetry that is a departure.

Crab and lobster claws

There are many compounds in carbohydrate have asymmetry structure like (glucose, mannose and glalactose) and also in amino acids ( L, D conformation).

The asymmetric distribution of various signal transduction molecules in early gestation, a classic example is the frog.

Even in the case of par of organs, as kidney, in mammals, asymmetry is the rule: the organs are note the same. Faces, legs, arms .... are symmetric? And we turn back to the question (see Schenk, above): depends on how to define asymmetry and asymmetry must be a necessity to understand time line.

Probably one of the most interesting examples regards with flatfishes, like soles and flounders, which suffer a profound metamorphosis during their larval stages... changing their external symmetry from being symmetric to asymmetric. Their metamorphosis is often linked with a change of their habitats, from the pelagic habitat to the bottom- settlement.

The 4 eye fish, Anableps, shows sexual organ asymmetry in both the male and female mating organs, "right"males only able to mate with "left" females, and vice versa

@van Dam. Is this mating exclusion confirmed by publication over the web expressed doubts? Since they are suggested to travel in familial schools does it lead to balanced selection for outbreeding? Is the handedness genetic or epigenetic and is their any dominance relationship known?

Of course, asymetry is in human being, too. For example: woman - gl. mammae or man - testes. These are two most frequently used examples. If I understood your question, correctly.

The antler (brow tines) of reindeer and caribou.

In attention to Joseph Kunkel:

Amoebae have asymmetric divisions for development and differentiation.

Cyclic encystment by terminal differentiation and quiescence by reversible differentiation are good examples for asymmetry in unicellular organisms (see my paper (abstract) about Entamoeba invadens, here in Research Gate)

@Vladimir:

I was not referring to your qualified reference to amoebic asymmetric divisions but the few unqualified posts such as "Amoeba, Sponges etc., show asymmetric structure", which do not provide enough detail to allow one to add them to a annotated list of asymmetries. This could be a valuable accumulation of examples if people qualified their examples as you have done. Not being an expert on sponges but having some experience with their position in evolution of morphological complexity I do not see at what level of organization they would provide a good example of asymmetry but I would be happy to entertain suggestions that bloggers might propose with their original posts or adjustments to those posts via discussion.

@Joseph: OK Joseph, I agree with you . Thank you for your letter

This article mentions quite a few asymmetries and gives references to the 4 eye fish Anableps: British Journal of Psychology (1980). 71, 329—367

Lateralization of functions in the vertebrate brain: A review

S. F. Walker.

I scowered the internet to obtain the aswers to Josephs pertinent questions but could only find some articles by Breder and/or D.E. Rosen that I do not have access to in their enterity, sorry!

Vocalization in a catfish and frogs.

BISAZZA, A., L. J. ROGERS, et al. (1998). “The Origins of Cerebral Asymmetry: A Review of Evidence of Behavioural and Brain Lateralization in Fishes, Reptiles and Amphibians.” Neuroscience and Biobehavioral Reviews, Vol. 22, No. 3, pp. 411–426.

The snails (Class Gastropoda, Phylum Mollusca) are a conspicuous example:

The phenomenom of "torsion" lead to an asymmetric development of pallial organs, ctenedium/s, osphradium/s, anus, and other organs, like the visceral ganglion of the nervous system...

The torsion can be fully, or unfinished, even can exist a posterior detorsion, so the visceral organs usualy turn assymetrics.

The torsion is the unique synaphomorphy of modern gastropod, and is unique in the animal kingdom.

among other examples, let's not forget the helically coiled ammonites belonging to the turrilitiid family (fossil cephalopods from the Upper Cretaceous)

what ever that has life is called an organism,,, now which organisms like KINGDOM... PHYLUM.... GENERA... CLASS..... SPECIES ETC SIR

Amoebas, paramecium , porifera, gastropods are examples of asymmetric animals.

the males of corixidae have dorsal asymemetry in the abdomen. Several families of heteroptera have the male genitalia asymmetric.

1. Fluctuating asymmetry is a widespread phenomenon that is the basis of sexual choice in vertebrates.

2. Vertebrate brains exhibit a variety of asymmetries. The most dramatic example is the habenula, which is always symmetrical in size or neural composition. In sharks the Right habenula may be an order of magnitude larger than it's partner on the Left

There is no such thing as a symmetric organism. Plants have roots at the bottom and leaves at the top, while animals generally have a mouth at one end and an arsehole at the other. Even unicellular organisms universally show some kind of polarity. All of these are asymmetries!

I think you need to define the question a bit better before you can get meaningful answers. Are you looking for examples where the majority of the body plan follows a symmetric organisation (e.g. bilaterality in vertebrates) but where the symmetry is locally broken? Or are you after a more general question of how axes become polarised - what makes a head different from a tail, how does the body "choose" an axis during development, etc.?

To @Peter's assertions, IMHO he has muddied the water about the concept of asymmetry, perhaps by intention to start his discussion. He asks what are we looking for? Symmetry is a model or concept that we apply to a living organism. Organisms will of course not precisely conform to that model but we argue that there are some axes of symmetry that particular species exhibit. Biologists have recognized and described graded degrees of symmetry in different organisms. When such a model has been applied we can talk about asymmetries that depart from that model. Without an assertion of a symmetry there is no reason to mention asymmetry. The question is, at what level of development is the assymetry imposed? Even the theory of fluctuating asymmetry asserts the possibility that, in some instances, it is not a concerted or planned asymmetry but just the biological noise of environmental random effects on the developing organism's symmetric parts. A list of examples of asymmetries was requested and the best responses IMHO have declared the symmetry that was departed from and even perhaps gave a reference. Examples in that list are then up for discussion, for instance, I questioned the simple inclusion of a sponge as an example of asymmetry. What is the symmetry that is being departed from in the sponges case?

Agree with Joseph. A concept, even a simpler one, is needed for symmetry. One, very simple of course, after all the concept seems to be borrowed from geometry, is the (virtual) presence of one (or several) axis wich produces at least two equal moities (or several). At molecular level, even in the case of smal molecules (not to mention proteins, ribosome etc,) biology is full crowded of non symmetric (asymmetric)n structures. At this level, non symmetry plays an important role for the production of specificity. While it is a little bit reductionistic view, I think is important to account for.

There are number of examples exhibiting structural or functional asymmetry in organisms in particularly with reference to human beings : 1. heart - left side of the heart receives oxygenated pure blood for distribution whereas right receives impure blood for oxygenation. 2. Right handed : right hand is stronger and functional whereas left handedness : left hand is functional. 3. In relation to the position of heart or liver --our body exhibits asymmetry .

There is no organism that is perfectly symmetrical. All exhibit asymmetry to some extent. even paired organs are not always the same size.

In thrips the right mandible is reduced or sometimes even absent, while the left forms a stylet used for piercing plants. The male fiddler crab has a huge claw, used for (often) ritual fighting and courtship displays, and a small used used in eating. If the large claw is lost, the smaller claw becomes the larger one in many species, or, in others, the large claw becomes bigger with successive molts.

Fore wings of Ensifera (Insecta: Orthoptera), involved in sound production.

A crab has one claw bigger than the other :-) Also octopuses have three hearts.

Also if you include the plant kingdom there are lots of asymmetries there.

Habitual unilateral mastication in humans results in asymmetry of the muscles. This is well known and readily seen on axial ct/mr images.

Gastropod shell and internal organization in shelled species is also an example of asimetry in nature.

I would also follow Peters's discourse. Asymmetry is rather the rule, beginning with the unicellular organisms. Maybe symmetric structures - like the skeleton of the diatoms - are a consequence of crystalin disposition of ions and molecules at that level, or, for multicellular ones, the effect of the natural selection for more efficient functioning in the environment, gravity considered (balance, speed). This may be the reason for the symmetry being one criterion for beauty, although seldom reached in fact. The symmetric structures themselves are not identical. Our ears, eyes, brain hemisferes, hands, muscles, blood vessels etc, all are different between themselves in some degree.

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