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Otolith

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Otolith
Otolith organs showing detail of utricle, otoconia, endolymph, cupula, macula, hair cell filaments, and saccular nerve
Juvenileherring.Length 30 mm; 3 months old; still transparent; the otoliths are visible left of the eye.
Details
Identifiers
Latinstatoconium
TA98A15.3.03.086
FMA77826
Anatomical terminology

Anotolith(Greek:ὠτο-,ōto-ear +λῐ́θος,líthos,a stone), also calledstatoconium,otoconiumorstatolith,is acalcium carbonatestructure in thesacculeorutricleof theinner ear,specifically in thevestibular systemofvertebrates.The saccule and utricle, in turn, together make theotolith organs.These organs are what allows an organism, including humans, to perceive linearacceleration,both horizontally and vertically (gravity). They have been identified in both extinct and extant vertebrates.[1]

Counting the annual growth rings on the otoliths is a common technique inestimating the age of fish.[2]

Description

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Endolymphatic infillings such as otoliths are structures in thesacculeandutricleof theinner ear,specifically in thevestibular labyrinthof allvertebrates(fish, amphibians, reptiles, mammals and birds). In vertebrates, the saccule and utricle together make theotolith organs.Both statoconia and otoliths are used as gravity, balance, movement, and directional indicators in all vertebrates and have a secondary function in sound detection in higher aquatic and terrestrial vertebrates.[3][4]They are sensitive togravityand linearacceleration.Because of their orientation in the head, the utricle is sensitive to a change in horizontal movement, and the saccule gives information about vertical acceleration (such as when in anelevator).

Similar balance receptors calledstatocystscan be found in manyinvertebrategroups but are not contained in the structure of an inner ear.Molluskstatocysts are of a similarmorphologyto thedisplacement-sensitive organs of vertebrates;[5]however, the function of the mollusk statocyst is restricted to gravity detection and possibly some detection of angular momentum.[6]These areanalogous structures,with similar form and function but notdescended from a common structure.

Statoconia (also called otoconia) are numerous grains, oftensphericalin shape, between 1 and 50μm;collectively.[citation needed]Statoconia are also sometimes termed a statocyst. Otoliths (also called statoliths) are agglutinated crystals or crystals precipitated around a nucleus, with well defined morphology and together all may be termed endolymphatic infillings.[1][7][8]

Morphology and terminology oflanternfish(Diaphus,left side)
andneoscopelidotoliths (Neoscopelus,right side) [9]

Mechanism

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Thesemicircular canalsand sacs in all vertebrates are attached to endolymphatic ducts, which in some groups (such assharks) end in small openings, called endolymphatic pores, on the dorsal surface of the head.[1]Extrinsic grains may enter through these openings, typically less than a millimeter in diameter. The size of material that enters is limited to sand-sized particles and in the case of sharks is bound together with an endogenous organic matrix that the animal secretes.

In mammals, otoliths are small particles, consisting of a combination of a gelatinous matrix andcalcium carbonatein the viscous fluid of the saccule and utricle. The weight andinertiaof these small particles causes them to stimulatehair cellswhen the head moves. The hair cells are made up of 40 to 70stereociliaand onekinocilium,which is connected to an afferent nerve. Hair cells send signals downsensory nerve fiberswhich are interpreted by the brain as motion. In addition to sensing acceleration of the head, the otoliths can help to sense the orientation via gravity's effect on them. When the head is in a normal upright position, the otolith presses on the sensory hair cell receptors. This pushes the hair cell processes down and prevents them from moving side to side. However, when the head is tilted, the pull of gravity on otoliths shifts the hair cell processes to the side, distorting them and sending a message to thecentral nervous systemthat the head is tilted.

There is evidence that the vestibular system of mammals has retained some of its ancestral acoustic sensitivity and that this sensitivity is mediated by the otolithic organs (most likely thesacculus,due to its anatomical location). In mice lacking the otoconia of the utricle and saccule, this retained acoustic sensitivity is lost.[4]In humansvestibular evoked myogenic potentialsoccur in response to loud, low-frequency acoustic stimulation in patients with the sensorineural hearing loss.[3]Vestibular sensitivity toultrasonic soundshas also been hypothesized to be involved in the perception of speech presented at artificially high frequencies, above the range of the humancochlea(~18 kHz).[10]In mice, sensation of acoustic information via the vestibular system has been demonstrated to have a behaviourally relevant effect; response to an elicitedacoustic startle reflexis larger in the presence of loud, low frequency sounds that are below the threshold for the mouse cochlea (~4 Hz), raising the possibility that the acoustic sensitivity of the vestibular system may extend the hearing range of small mammals.[4]

Paleontology

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After the death and decomposition of a fish, otoliths may be preserved within the body of an organism or be dispersed before burial andfossilization.Dispersed otoliths are one of the manymicrofossilswhich can be found through a micropalaeontological analysis of a fine sediment. Theirstratigraphicsignificance is minimal, but can still be used to characterize a level or interval. Fossil otoliths are rarely foundin situ(on the remains of the animal), likely because they are not recognized separately from the surrounding rock matrix. In some cases, due to differences in colour, grain size, or a distinctive shape, they can be identified. These rare cases are of special significance, since the presence, composition, and morphology of the material can clarify the relationship of species and groups. In the case of primitive fish, various fossil material shows thatendolymphaticinfillings were similar in elemental composition to the rock matrix but were restricted to coarse grained material, which presumably is better for the detection of gravity, displacement, and sound. The presence of these extrinsic grains inosteostracans,chondrichthyans,andacanthodiansindicates a common inner ear physiology and presence of open endolymphatic ducts.[1]

An unclassified fossil namedGluteus minimushas been thought to be possible otoliths, but it is hitherto unknown to which animal they could belong to.

Ecology

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Composition

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Animation of the biomineralization ofcodotoliths

The composition of fish otoliths is also proving useful to fisheries scientists. The calcium carbonate that the otolith is composed of is primarily derived from the water. As the otolith grows, new calcium carbonate crystals form. As with any crystal structure, lattice vacancies will exist during crystal formation allowing trace elements from the water to bind with the otolith. Studying the trace elemental composition orisotopic signaturesof trace elements within a fish otolith gives insight to the water bodies fish have previously occupied.[11]Fish otoliths as old as 172 million years have been used to study the environment in which the fish lived.[12]Robotic micromilling devices have also been used to recover very high resolution records of life history, including diet and temperatures throughout the life of the fish, as well as their natal origin.[13]

The most studied trace and isotopic signatures arestrontiumdue to the same charge and similarionic radiustocalcium;however, scientists can study multiple trace elements within an otolith to discriminate more specific signatures. A common tool used to measure trace elements in an otolith is alaser ablation inductively coupled plasma mass spectrometer.This tool can measure a variety of trace elements simultaneously. Asecondary ion mass spectrometercan also be used. This instrument can allow for greater chemical resolution but can only measure one trace element at a time. The hope of this research is to provide scientists with valuable information on where fish have frequented. Combined with otolith annuli, scientists can add how old fish were when they traveled through different bodies of water. This information can be used to determine fish life cycles so that fisheries scientists can make better informed decisions about fish stocks.

Growth rate and age

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A pair of sagittae from aPacific Cod(Gadus macrocephalus)
Removing an otolith from ared snapperto determine its age
See also:Estimating the age of fish

Finfish(classOsteichthyes) have three pairs of otoliths – the sagittae (singular sagitta), lapilli (singular lapillus), and asterisci (singular asteriscus). The sagittae are largest, found just behind the eyes and approximately level with them vertically. The lapilli and asterisci (smallest of the three) are located within the semicircular canals. The sagittae are normally composed ofaragonite(althoughvateriteabnormalities can occur[14]), as are the lapilli, while the asterisci are normally composed of vaterite.

The shapes and proportional sizes of the otoliths vary with fish species. In general, fish from highly structured habitats such as reefs or rocky bottoms (e.g.snappers,groupers,manydrums and croakers) will have larger otoliths than fish that spend most of their time swimming at high speed in straight lines in the open ocean (e.g.tuna,mackerel,dolphinfish).Flying fishhave unusually large otoliths, possibly due to their need for balance when launching themselves out of the water to "fly" in the air. Often, the fish species can be identified from distinct morphological characteristics of an isolated otolith.

Fish otoliths accrete layers ofcalcium carbonateand gelatinous matrix throughout their lives. The accretion rate varies with growth of the fish – often less growth in winter and more in summer – which results in the appearance of rings that resembletree rings.By counting the rings, it is possible to determine the age of the fish in years.[15]Typically the sagitta is used, as it is largest,[16]but sometimes lapilli are used if they have a more convenient shape. The asteriscus, which is smallest of the three, is rarely used in age and growth studies.

In addition, in most species the accretion of calcium carbonate and gelatinous matrix alternates on a daily cycle. It is therefore also possible to determine fish age in days.[17]This latter information is often obtained under a microscope, and provides significant data to early life history studies.

By measuring the thickness of individual rings, it has been assumed (at least in some species) to estimate fish growth because fish growth is directly proportional to otolith growth.[18]However, some studies disprove a direct link between body growth and otolith growth. At times of lower or zero body growth the otolith continues to accrete leading some researchers to believe the direct link is to metabolism, not growth per se. Otoliths, unlike scales, do not reabsorb during times of decreased energy making it even more useful tool to age a fish. Fish never stop growing entirely, though growth rate in mature fish is reduced. Rings corresponding to later parts of the life cycle tend to be closer together as a result. Furthermore, a small percentage of otoliths in some species bear deformities over time.[19]

Age and growth studies of fish are important for understanding such things as timing and magnitude of spawning, recruitment and habitat use, larval and juvenile duration, andpopulation age structure.Such knowledge is in turn important for designing appropriatefisheriesmanagement policies. Due to the amount of required human labour in otolith age reading, there is active research in automating that process.[20]

Diet research

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Since the compounds in fish otoliths are resistant todigestion,they are found in thedigestive tractsandscatsof seabirds andpiscivorousmarine mammals,such asdolphins,seals,sea lionsandwalruses.Many fish can be identified togenusandspeciesby their otoliths. Otoliths can therefore, to some extent, be used to deduce and reconstruct the prey composition of marine mammal and seabird diets.

Otoliths (sagittae) arebilaterally symmetrical,with each fish having one right and one left. Separating recovered otoliths into right and left, therefore, allows one to infer a minimum number of prey individuals ingested for a given fish species. Otolith size is also proportional to the length and weight of a fish. They can therefore be used to back-calculate prey size andbiomass,useful when trying to estimatemarine mammalprey consumption, and potential impacts onfish stocks.[21]

Otoliths cannot be used alone to reliably estimatecetaceanorpinnipeddiets, however. They may suffer partial or completeerosionin the digestive tract, skewing measurements of prey number andbiomass.[22]Species with fragile, easily digested otoliths may be underestimated in the diet. To address these biases, otolith correction factors have been developed through captive feeding experiments, in which seals are fed fish of known size, and the degree of otolith erosion is quantified for different preytaxa.[23]

The inclusion of fishvertebrae,jaw bones, teeth, and other informative skeletal elements improves prey identification and quantification over otolith analysis alone.[24]This is especially true for fish species with fragile otoliths, but other distinctive bones, such asAtlantic mackerel(Scomber scombrus), andAtlantic herring(Clupea harengus).[25]

Otolith ornaments

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'Sea gems' ornaments from fish otoliths have been introduced in the market in India recently, with the efforts of a group of enthusiastic fisher women inVizhinjam.Scientists fromCentral Marine Fisheries Research Institute(CMFRI) have trained these fisher-women. Ornaments from fish otoliths, known to the Romans and Egyptians as lucky stones, are continued to be used in countries like Brazil and the Faeröer, and are being collected and sold in an organized and sustainable manner in India.[26]

See also

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References

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Wikimedia Commons has media related toOtoliths.
  1. ^abcdSahney, Sarda; Wilson, Mark V. H. (2001). "Extrinsic labyrinth infillings imply open endolymphatic ducts in Lower Devonian osteostracans, acanthodians, and putative chondrichthyans".Journal of Vertebrate Paleontology.21(4): 660–669.doi:10.1671/0272-4634(2001)021[0660:ELIIOE]2.0.CO;2.S2CID86182956.
  2. ^Gordon, D.P. (2009).New Zealand inventory of biodiversity: 1. Kingdom Animalia: Radiata, Lophotrochozoa, Deuterostomia.Christchurch: Canterbury University Press. p. 459.ISBN978-1-877257-72-8.
  3. ^abSheykholeslami, Kianoush; Kaga, Kimitaka (2002). "The otolithic organ as a receptor of vestibular hearing revealed by vestibular-evoked myogenic potentials in patients with inner ear anomalies".Hearing Research.165(1–2): 62–67.doi:10.1016/S0378-5955(02)00278-2.ISSN0378-5955.PMID12031516.S2CID23530754.
  4. ^abcJones, Gareth P.; Lukashkina, Victoria A.; Russell, Ian J.; Lukashkin, Andrei N. (2010)."The Vestibular System Mediates Sensation of Low-Frequency Sounds in Mice".Journal of the Association for Research in Otolaryngology.11(4): 725–732.doi:10.1007/s10162-010-0230-7.ISSN1525-3961.PMC2975890.PMID20821033.
  5. ^Gauldie, R. W. (1993). "Polymorphic crystalline structure of fish otoliths".Journal of Morphology.218(1): 1–28.doi:10.1002/jmor.1052180102.PMID29865482.S2CID46932904.
  6. ^Wolff, Heinz G. (1973). "Multi-directional sensitivity of statocyst receptor cells of the opisthobranch gastropodAplysia limacina".Marine Behavior and Physiology.1(1–4): 361–373.doi:10.1080/10236247209386910.
  7. ^Nolf, D. 1985. Otolithi Piscium; in H.-P. Schultze (ed.), Handbook of Paleoichthyology, Vol. 10. Gustav Fischer Verlag, Stuttgart, 145pp.
  8. ^Schultze, H.-P. (1990). "A new acanthodian from the Pennsylvanian of Utah, U.S.A. and the distribution of otoliths in gnathostomes".Journal of Vertebrate Paleontology.10(1): 49–58.doi:10.1080/02724634.1990.10011789.
  9. ^Schwarzhans, Werner; Carnevale, Giorgio (19 March 2021)."The rise to dominance of lanternfishes (Teleostei: Myctophidae) in the oceanic ecosystems: a paleontological perspective".Paleobiology.47(3). Cambridge University Press (CUP): 446–463.doi:10.1017/pab.2021.2.ISSN0094-8373.S2CID233678539.Material was copied from this source, which is available under aCreative Commons Attribution 4.0 International License.
  10. ^Lenhardt, M.; Skellett, R; Wang, P; Clarke, A. (1991). "Human ultrasonic speech perception".Science.253(5015): 82–85.Bibcode:1991Sci...253...82L.doi:10.1126/science.2063208.ISSN0036-8075.PMID2063208.
  11. ^Patterson, William P.; Smith, Gerald R.; Lohmann, Kyger C. (1993). "Continental Paleothermometry and Seasonality Using the Isotopic Composition of Aragonitic Otoliths of Freshwater Fishes".Climate Change in Continental Isotopic Records.Geophysical Monograph Series. Vol. 78. pp. 191–202.Bibcode:1993GMS....78..191P.doi:10.1029/GM078p0191.ISBN9781118664025.
  12. ^Patterson, William P. (1999)."Oldest isotopically characterized fish otoliths provide insight to Jurassic continental climate of Europe".Geology.27(3): 199.Bibcode:1999Geo....27..199P.doi:10.1130/0091-7613(1999)027<0199:OICFOP>2.3.CO;2.
  13. ^Zazzo, A.; Smith, G. R.; Patterson, W. P.; Dufour, E. (2006)."Life history reconstruction of modern and fossil sockeye salmon (Oncorhynchus nerka) by oxygen isotopic analysis of otoliths, vertebrae, and teeth: Implication for paleoenvironmental reconstructions ".Earth and Planetary Science Letters.249(3/4): 200–215.doi:10.1016/j.epsl.2006.07.003.
  14. ^Reimer, T.; Dempster, T.; Warren-Myers, F.; Jensen, A. J.; Swearer, S. E. (2016)."High prevalence of vaterite in sagittal otoliths causes hearing impairment in farmed fish".Scientific Reports.6:25249.Bibcode:2016NatSR...625249R.doi:10.1038/srep25249.PMC4848507.PMID27121086.
  15. ^Kimura, Daniel K.; Anderl, Delsa M. (2005)."Quality control of age data at the Alaska Fisheries Science Center"(PDF).Marine and Freshwater Research.56(5): 783–789.doi:10.1071/mf04141.
  16. ^Fish Age and Growth with OtolithsTennessee Wildlife Resources Agency. Retrieved 2007-04-07.
  17. ^Bos, A.R. (1999)."Tidal transport of flounder larvae (Pleuronectes flesus) in the River Elbe, Germany ".Archive of Fishery and Marine Research.47(1): 47–60.
  18. ^Jones, Cynthia M.(1992). "Development and application of the otolith increment technique". In D. K. Stevenson; S.E. Campana (eds.).Otolith microstructure examination and analysis.Canadian Special Publication of Fisheries and Aquatic Sciences. Vol. 117. pp. 1–11.
  19. ^Lackmann, Alec R.; Andrews, Allen H.; Butler, Malcolm G.; Bielak-Lackmann, Ewelina S.; Clark, Mark E. (2019-05-23)."Bigmouth BuffaloIctiobus cyprinellussets freshwater teleost record as improved age analysis reveals centenarian longevity ".Communications Biology.2(1): 197.doi:10.1038/s42003-019-0452-0.ISSN2399-3642.PMC6533251.PMID31149641.
  20. ^Sigurðardóttir, Andrea Rakel; Sverrisson, Þór; Jónsdóttir, Aðalbjörg; Gudjónsdóttir, María; Elvarsson, Bjarki Þór; Einarsson, Hafsteinn (2023-09-01)."Otolith age determination with a simple computer vision based few-shot learning method".Ecological Informatics.76:102046.doi:10.1016/j.ecoinf.2023.102046.ISSN1574-9541.
  21. ^Arim, Matías; Naya, Daniel E. (2003). "Pinniped diets inferred from scats: Analysis of biases in prey occurrence".Canadian Journal of Zoology.81(1): 67–73.doi:10.1139/z02-221.
  22. ^Bowen, W. D. (2000). "Reconstruction of pinniped diets: Accounting for complete digestion of otoliths and cephalopod beaks".Canadian Journal of Fisheries and Aquatic Sciences.57(5): 898–905.doi:10.1139/f00-032.
  23. ^Grellier, K.; Hammond, P. S. (2005). "Feeding method affects otolith digestion in captive gray seals: Implications for diet composition estimation".Marine Mammal Science.21(2): 296–306.doi:10.1111/j.1748-7692.2005.tb01229.x.
  24. ^Browne, Patience; Laake, Jeffrey L.; DeLong, Robert L. (2002)."Improving pinniped diet analyses through identification of multiple skeletal structures in fecal samples"(PDF).Fishery Bulletin.100(3): 423–433.
  25. ^Ouwehand, J.; Leopold, M. F.; Camphuysen, C. J. (2004)."A comparative study of the diet of GuillemotsUria aalgeand RazorbillsAlca tordakilled during theTricoloroil incident in the south-eastern North Sea in January 2003 "(PDF).Atlantic Seabirds.6(3): 147–163. Archived fromthe original(PDF)on August 6, 2020.
  26. ^"FISH OTOLITH ORNAMENTS MAKE MARKET DEBUT".Universal Group Of Institutions.31 March 2024.Retrieved31 March2024.
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