Otoliths recoveries

[Alto Mare]

Very nice Gary! Dominick, I agree! We're always learning here.

Sal

[gstours]

  Thanks for the seemingly ok to keep going on this otolith subject without any more pictures.  My black lab is typing this so hey he dont care.
   As I stated many things can be learned from the otoliths.  I shoulda coulda said most and if not all parts of any fish.  My focus was simply though time, ive seen jewelry made from the otoliths and had been curious to them as they were pure white, and had a pure earthy thing about them.   So the few ive recovered took me to a new appreciation level.   Not only to appreciate the donor, butt to recover these whenever possible, time and situations providing, and using these for art, or jewelry or maybee the inner frame of a picture in a locket.
   Heres some more scientific information on my subject.
Mechanism

The semicircular canals and sacs in all vertebrates are attached to endolymphatic ducts, which in some groups (such as sharks) 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 endogenous an organic matrix that the animal secretes.

In mammals, otoliths are small particles, composed of a combination of a gelatinous matrix and calcium carbonate in the viscous fluid of the saccule and utricle. The inertia of these small particles causes them to stimulate hair cells when the head moves. The hair cells are made up of 40 to 70 stereocilia and one kinocilium, which is connected to an afferent nerve. When the body changes position or begins a movement the weight of the membrane bends the stereocilia and stimulates the hair cells. Hair cells send signals down sensory nerve fibers, which are interpreted by the brain as motion. The brain interprets the orientation of the head by comparing the input from the utricles and saccules from both ears to the input from the eyes, allowing the brain to discriminate a tilted head from the movement of the entire body. 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 shift the hair cell processes to the side, distorting them and sending a message to the central nervous system that the head is no longer level but now tilted. (see: BPPV) This theory may have to be reevaluated because of an experiment in which a blindfolded owl in zero gravity was able to keep its head level while a handler was rocking its body back and forth.[8]

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 the sacculus, due to its anatomical location). In mice lacking the otoconia of the utricle and saccule, this retained acoustic sensitivity is lost.[3] In humans vestibular evoked myogenic potentials occur in response to loud, low-frequency acoustic stimulation in patients with the sensorineural hearing loss.[2] Vestibular sensitivity to ultrasonic sounds has also been hypothesized to be involved in the perception of speech presented at artificially high frequencies, above the range of the human cochlea (~18 kHz).[9] In mice sensation of acoustic information via the vestibular system has been demonstrated to have a behaviourally relevant effect; response to an elicited acoustic startle reflex is 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.[3]
Paleontology

After the death and decomposition of a fish, otoliths may be preserved within the body of an organism or be dispersed before burial and fossilization. Dispersed otoliths are one of the many microfossils which can be found through a micropalaeontological analysis of a fine sediment. Their stratigraphic significance is minimal, but can still be used to characterize a level or interval. Fossil otoliths are rarely found in 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 that endolymphatic infillings 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, in osteostracans, chondrichthyans, and acanthodians indicates a common inner ear physiology and presence of open endolymphatic ducts.[1]
Composition
File:Shedding-Light-on-Fish-Otolith-Biomineralization-Using-a-Bioenergetic-Approach-pone.0027055.s013.ogvPlay media
Animation of the biomineralization of cod otoliths

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 or isotopic signatures of trace elements within a fish otolith gives insight to the water bodies fish have previously occupied.[10] Fish otoliths as old as 172 million years have been used to study the environment in which the fish lived.[11] 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.[12]

The most studied trace and isotopic signatures are strontium due to the same charge and similar ionic radius to calcium; 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 a laser ablation inductively coupled plasma mass spectrometer. This tool can measure a variety of trace elements simultaneously. A secondary ion mass spectrometer can 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 traveled. Combined with otolith annuli, scientists can add how old fish were when they traveled through different water bodies. All this information can be used to determine fish life cycles so that fisheries scientists can make better informed decisions about fish stocks.
See also: estimating the age of fish

Finfish (class Osteichthyes) 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 of aragonite (although vaterite abnormalities can occur[13]), 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, many drums 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 fish have 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 of calcium carbonate and 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 resemble tree rings. By counting the rings, it is possible to determine the age of the fish in years.[14] Typically the sagitta is used, as it is largest,[15] 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.[16] 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. 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.
Since the compounds in fish otoliths are resistant to digestion, they are found in the digestive tracts and scats of piscivorous marine mammals, such as dolphins, seals, sea lions and walruses. Many fish can be identified to genus and species by their sagittal otoliths. Otoliths can therefore, to some extent, be used to reconstruct the prey composition of marine mammal diets.

Sagittal otoliths (sagittae) are bilaterally 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 and biomass, useful when trying to estimate marine mammal prey consumption, and potential impacts on fish stocks.[17]
   This is just a brief over view of the little ear stones from which my few pictures were from.
        Now for a picture to make this post pass muster.


   

[oldmanjoe]

    Thank you for that write up and education ....   joe

[sdlehr]

I will add that  otoliths in people are frequently responsible for Minnear's disease, a disorder of balance caused by the aberrant stimulation of hair cells in the human ear that should not be stimulated - causes vertigo in the individual affected and can be very debilitating.