Myochordotonal Organ Research Articles

Sound reception in crabs: Keeping an ear to the wind and a leg to the ground

Event Abstract Back to Event Sound reception in crabs: Keeping an ear to the wind and a leg to the ground Micah J. Waltz1* and Jim H. Belanger1, 2 1 West Virginia University, Dept of Physiology and Pharmacology, United States 2 West Virginia University, Dept. of Biology, United States Acoustic information from the environment can exist in two different forms: medium-borne pressure waves in air or water, or vibrations traveling through a solid substrate such as rock or earth. Many animals have specialized sensors for detecting this kind of information, and using it to direct behavior. For example, some land crabs use acoustic information in mating behaviors and startle responses. They have sensors that are thought to respond to sound waves (Barth’s myochordotonal organs on the walking legs) and other sensors that are thought to respond to substrate vibration (campaniform sensillae on the dactyls). We are interested in the differing sensory capabilities of these organs, and in particular the ways that sound and vibration stimuli may be combined for behavioral decisions. As a first step in this study, we are analyzing the response characteristics of the sensors to different types of stimuli. In fiddler crabs (Uca pugnax),airborne stimulation of the membrane overlying Barth’s myochordotonal organ produces much larger responses (higher frequency and greater diversity of action potentials) than tactile stimulation of the membrane. In contrast, only tactile stimulation of the campaniform sensillae produces any response. . This suggests that the two types of organs are responding to different aspects of sound, allowing crabs to construct a fuller picture of the environment. Keywords: acoustic, crustacean, Hearing, Sound, vibrations Conference: Tenth International Congress of Neuroethology, College Park. Maryland USA, United States, 5 Aug - 10 Aug, 2012. Presentation Type: Poster (but consider for student poster award) Topic: Sensory: Audition Citation: Waltz MJ and Belanger JH (2012). Sound reception in crabs: Keeping an ear to the wind and a leg to the ground. Conference Abstract: Tenth International Congress of Neuroethology. doi: 10.3389/conf.fnbeh.2012.27.00343 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 30 Apr 2012; Published Online: 07 Jul 2012. * Correspondence: Mr. Micah J Waltz, West Virginia University, Dept of Physiology and Pharmacology, Morgantown, WV, 26505, United States, mwaltz@hsc.wvu.edu Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Micah J Waltz Jim H Belanger Google Micah J Waltz Jim H Belanger Google Scholar Micah J Waltz Jim H Belanger PubMed Micah J Waltz Jim H Belanger Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Sound production and reception in mangrove crabs Perisesarma spp. (Brachyura: Sesarmidae)

Acoustic signalling and sound production structures in the sesarmid crabs Perisesarma eumolpe (De Man) and P. indiarum (Tweedie) from Mandai mangroves, Singapore, were examined using 40 to 20 000 Hz sound recordings and scanning electron microscopy. The sound receptor, Barth's myochordotonal organ, was identified in both species. Only male crabs were found to display acoustically, and only during agonistic interactions. The present study also revealed key species- specific differences in the morphology of the stridulatory organs, stridulatory movements and result- ing sounds produced. The findings show that acoustic signalling may be a significant component in the social behaviour of mangrove sesarmid crabs.

Connections Between Thoraco-Coxal Proprioceptive Afferents and Motor Neurons in the Locust

The position of the coxal segment of the locust hind leg relative to the thorax is monitored by a variety of proprioceptors, including three chordotonal organs and a myochordotonal organ. The sensory neurons of two of these proprioceptors, the posterior joint chordotonal organ (pjCO) and the myochordotonal organ (MCO), have axons in the purely sensory metathoracic nerve 2C (N2C). The connections made by these afferents with metathoracic motor neurons innervating thoraco-coxal and wing muscles were investigated by electrical stimulation of N2C and by matching postsynaptic potentials in motor neurons with afferent spikes in N2C. Stretch applied to the anterior rotator muscle of the coxa (M121), with which the MCO is associated, evoked sensory spikes in N2C. Some of the MCO afferent neurons make direct excitatory chemical synaptic connections with motor neurons innervating the thoraco-coxal muscles M121, M126 and M125. Parallel polysynaptic pathways via unidentified interneurons also exist between MCO afferents and these motor neurons. Connections with the common inhibitor 1 neuron and motor neurons innervating the thoraco-coxal muscles M123/4 and wing muscles M113 and M127 are polysynaptic. Afferents of the pjCO also make polysynaptic connections with motor neurons innervating thoraco-coxal and wing muscles, but no evidence for monosynaptic pathways was found.

Proprioceptors of the thoracic limbs of Squilla mantis (Crustacea, Stomatopoda)

The distribution and morphology of the internal proprioceptive organs in the thoracic appendages of the stomatopod crustacean, Squilla mantis, are described. Five distinct types of proprioceptor are recognised; connective chordotonal organ, myochordotonal organ, cuticular stress detector, multiterminal stretch receptor and apodeme stretch receptor. The connective chordotonal organs and multiterminal receptors exhibit a wide variety of structural and functional complexity. The stomatopods resemble the decapods in that the basic proprioceptive unit of the thoracic appendages appears to be the connective chordotonal organ, but differs in the higher occurrence of multiterminal stretch receptors. As described for decapods, the pereiopods of stomatopods possess the largest number and greatest variety of proprioceptors, suggesting that locomotion exerts greater selective pressure on proprioceptor development than do the other thoracic limb functions, including the raptorial strike.

The motor program and role of sensory feedback in claw extension of the crayfish

The motor program and role of the meropodite sensory organs (the chordotonal organs MC-1, MC-2 and the myochordotonal organ MCO) in extension of the merocarpodite (M-C) joint of the claw was examined during an antennal-evoked defense response. Recordings from the meropodite extensor muscle indicated that the tonic extensor motoneuron was primarily responsible for M-C joint extension. The phasic extensor motoneuron was co-activated with the tonic motoneuron in only 48% of the responses. Tonic motoneuron discharge was elevated in those responses in which the phasic motoneuron was active. Inactivation of individual meropodite sensory organs did not alter the tonic motoneuron response. Simultaneous inactivation of all 3 organs reduced tonic motoneuron discharge by 47%. Phasic motoneuron discharge was reduced following inactivation of the individual MC-1, MC-2 and MCO organs as well as in the sham operated group. Following inactivation of all 3 organs phasic motoneuron activity ceased. These results suggest that feedback from the M-C sensory organs during an active extension response is positive and redundant.

A new muscle receptor organ in the antenna of the rock lobster Palinurus vulgaris : mechanical, muscular and proprioceptive organization of the two proximal joints J0 and J1

(i) Following previous work on the morphological and physiological properties of the two distal joints (J2, J3) of the atenna of the rock lobster Palinurus vulgaris , the mechanical, muscular and proprioceptive organization of the two proximal joints between the antennal segments S1 and S2 (J1) and between S1 and the cephalothorax (J0) have now been studied. (ii) Articulated by two classical condyles, J1 moves in a mediolateral plane. One external rotator muscle (ER) and three internal rotator muscles (IR1, IR2, IR3) subserve its movements. J0 is articulated by two different systems: a classical ventrolateral condyle and a complex sliding system constituted by special cuticular structures on the dorsomedial side of the S1 segment and on the rostrum between the two antennae. J0 moves in the dorsoventral plane by means of a levator muscle (Lm) and a depressor muscle (Dm). A third muscle, the lateral tractor muscle (LTm), associated with J0 and lying obliquely across S1, may modulate the level of friction between the S1 segment and the rostrum. (iii) Proprioception in J1 is achieved by a muscle receptor organ AMCO-J1 (antennal myochordotonal organ for the J1 joint) associating a small accessory muscle (S1.am) located in the proximal part of the S1 segment and a chordotonal organ inserted proximally on the S1.am muscle and distally on the S2 segment. J0 proprioception is ensured by a simple chordotonal organ (CO-J0) located in the anterior part of the cephalothorax. (iv) The S1.am muscle is innervated by three motoneurons characterized by their very small diameters and inducing respectively tonic excitatory postsynaptic potentials, phasic excitatory postsynaptic potentials and inhibitory postsynaptic potentials. Anatomical and physiological observations suggest functional correlation between S1.am and IR1 motor innervation. (v) Mechanical and muscular organization of J0 and J1 are compared with that of the other joints of the antenna. The properties of the AMCO-J1 proprioceptor are discussed in relation to the other muscle receptor organs described in crustaceans.

Trajectory analysis by a crayfish proprioceptor: Receptor muscle activity may determine a velocity reference point

The myochordotonal organ, spanning the merus-carpus joint consists of a receptor muscle called the accessory flexor which is closely associated with sensory neurons. These neurons are attached to a connective tissue strap which stretches between a portion of the accessory flexor and the adjacent cuticle of the meropodite. The activity of this proprioceptor was examined during both passive and spontaneous flexions of the merus-carpus joint as well as under conditions of inertial loading and de-efferentation of the receptor muscle. During passively imposed movements, the sensory neurons discharge closely in proportion to joint velocity. However in self-generated movements the velocity sensitivity of these neurons changes greatly and may even reverse. We suggest that these changes in velocity sensitivity may be explained in terms of a previously undescribed property of proprioceptors which have an efferent input. We have called this property the reference trajectory of the proprioceptor. We have defined reference velocity trajectory as the time series of stimulus velocities at which the proprioceptor's discharge is minimal. In passive receptors this sequence would not change in time. In the case of the myochordotonal organ, however, the stimulus velocities at which the receptor output is minimal changes when there is motor activity in the receptor muscle. Immediately prior to a spontaneous flexion, the reference velocity trajectory of the myochordotonal organ rises from 0/s to 20–40/s. During the movement the trajectory normally stays at this level falling back to zero only after the movement is stopped. Our data suggest that during spontaneous flexion the myochordotonal organ encodes the direction as well as the magnitude of the deviations of actual joint velocity from its reference velocity trajectory. The sensing of this difference is referred to as trajectory analysis. A mechanism of trajectory analysis is proposed in terms of the changes in forces which occur in the receptor muscle during a spontaneous movement.

Postural Reflexes Coordinating Walking Legs in a Rock Lobster

Postural Reflexes Coordinating Walking Legs in a Rock Lobster

Intersegmental reflex actions from a joint sensory organ (CB) to a muscle receptor (MCO) in decapod crustacean limbs.

In the walking legs of decapod crustaceans, intersegmental reflex actions originate from various joint proprioceptors. The activity of the 'accessory flexor' (AF) muscle, which with the myochordotonal organ (MCO) constitutes a muscle proprioceptor for the mero-carpopodite (M-C) joint, is modulated by the sensory discharge of a joint receptor (CB chordotonal organ) for the more proximal, coxo-basal (C-B) joint. Selective mechanical stimulation of the CB organ also reflexly modifies the motor activities of the main M-C flexor and extensor muscles (recorded as EMGs). 1. Dynamic CB stretch (as would occur during a dorso-ventral C-B movement - i.e. 'depression' of the limb) stimulates motor discharge to the M-C extensor muscle, while dynamic release of CB (as during a ventrodorsal C-B movement - or leg 'elevation') excites the accessory flexor as well as the main flexor muscle. 2. Successive M-C muscle responses to repetitive sinusoidal changes of CB length differ quantitatively according to the direction (stretch or release) of the first CB movement, in some cases increasing but more commonly 'adapting' with repetition. 3. Reflex discharge frequencies of the extensor, flexor and accessory flexor motoneurones increase with velocity of CB movement. 4. Eye illumination, and spontaneous or other sources of increased central excitability, generally increase the CB reflex drive to the flexor and accessory flexor muscles and, in parallel, decrease the reflex action on the extensor muscle. The results are discussed in terms of the role of proprioceptive reflexes in intersegmental co-ordination of the leg joints. In particular the significance of the reflex regulation of the myochordotonal receptors, and thereby the gain of the M-C resistance reflexes, is considered in the light of the observed 'co-activation' of main flexor and receptor muscle motoneurones.

Unusual thick and thin filament packing in a crustacean muscle.

The proximal accessory flexor (PAF) of the myochordotonal organ (MCO) in the meropodite of crayfish walking legs contains two populations of muscle fibers which are distinguishable by their diameters. The large accessory (LA) fibers are 40-80 micrometer in diam and are similar in ultrastructure to other slow crustacean fibers. The small accessory (SA) fibers are 1-12 micrometer in diam and have a unique myofilament distribution at normal body lengths. There is extensive double overlap of thin filaments at these lengths, and some of them form bundles that may extend the length of the sarcomere. In the middle of the sarcomeres, thick and thin filaments are totally segregated from each other. When the fibers are stretched to lengths beyond double overlap length, the myofilament patterns are conventional. The segregated pattern is reestablished when stretched fibers are allowed to shorten passively. The length-tension relationship of the SA fibers is described by a linear ascending branch, a plateau, and a linear descending branch. The ascending branch encompasses normal body lengths from slack length (Ls) with maximum double overlap to the length at which double overlap ceases (1.8 X Ls). The descending phase is comparable to that of other skeletal muscles. That is, tension decreases in proportion with the reduction in thick-thin filament interdigitation (2 X Ls to 3 X Ls).

Barth's myochordotonal organ as a receptor for auditory and vibrational stimuli in fiddler crabs(Uca pugilatorandU. minax)

The sensitivity of fiddler crabs to air‐ and substrate‐borne acoustic stimuli (pure tones) was studied, using responses of interneurons in the supra‐oesophageal ganglion for the measurements. Intact Uca pugilator could detect stimuli as both air‐borne (sound) and vibrational energies, but were much more sensitive to the latter. This finding, coupled with previous measurements of its own courtship sounds, indicated that only sound carried through the substrate was important for intraspecific communication. Destruction of Barth's Myochordotonal organ in the walking legs of both U. pugilator and U. minax decreased sensitivity to vibration by 8–20 dB. The effect was evident across the entire sensitivity spectrum, but most pronounced at the higher frequencies. The external anatomy of the receptor is described, as revealed by scanning EM study.

Sensory-motor interactions in antennal reflexes of the American lobster

1. The behavior, proprioceptors, musculature, and innervation of the distal three segments of the antenna of the American lobster,Homarus americanus, were studied. 2. The unrestrained lobster moves the two distal joints of the antenna in two ways: 1) simultaneous extension or flexion at both joints, or 2) movement of the distal segment by itself. 3. Sensory information about the movements at the two joints is provided mainly by two proprioceptors, the MCF chordotonal organ spanning both joints and the CF myochordotonal organ spanning the most distal joint. 4. The MCF chordotonal organ is an unusual proprioceptor in that some of its units respond similarly to movement at either joint. 5. Movement at the two distal joints is controlled by four muscles, one pair of flexors and one pair of extensors. 6. The innervation pattern involves seven excitatory motor neurons: one independent motor neuron to each of the four muscles, one common motor neuron to the flexor muscles, and two common motor neurons to the extensor muscles. 7. Induced joint movements generate resistance-reflex responses: flexion drives the two independent extensor motor neurons E4 and E5 and one of the two common extensor motor neurons EC1; extension drives the independent motor neurons F4 and F5. The response is the same to movement at either joint. 8. Direct mechanical stimulation of the MCF chordotonal organ also generates resistance reflexes: stretch drives the flexor motor neurons F4 and F5; relaxation drives extensor motor neurons E4, E5, and EC1. These responses are similar to those produced by induced joint movement. 9. The functional significance of the relationship between the common proprioceptor and the motor neurons is discussed.

Reflex modulation of motoneurone activity in the cheliped of the crayfish Astacus leptodactylus.

1. The reflex activity elicited by movement of the mero-carpopodite (M-C) joint in the cheliped of the crayfish Astacus leptodactylus is investigated and the role of the different proprioceptors (chordotonal and myochordotonal organs) separately studied. 2. The reflex discharge involves mainly the tonic motoneurones of the extensor (E), the flexor (F) and the accessory flexor (AF) muscles. 3. M-C joint posture is also regulated by the cuticular stress detector (CSD2) afferents: they increase mainly the F discharge and secondarily the AF command. 4. The activity of the motor axons supplying the muscles of the meropodite can be also influenced by a variety of natural stimuli applied to other appendages. The effect usually produced is a general flexion reaction which is characterized by a reciprocity between E and F involving both central and peripheral mechanisms. 5. The AF muscle is innervated by two antagonistic motoneurones, an excitatory neurone functionally linked in its discharge with one of the four excitors supplying F and an inhibitory motoneurone, common with E. The resulting competitive effect between these two neurones has been recorded intracellularly in AF muscle fibres. 6. The role of the myochordotonal organ (MCO) in the crayfish is discussed. In particular the modulation of the AF command in relation to the discharges of the motor nerves to the main muscle E and F is studied.

The Acoustic Behavior of the Ghost Crab Ocypode Cordimana Latreille, 1818 (Decapoda, Brachyura)

The ghost crabs, Ocypode, are unique among crustaceans in that all but one species possess a specialized stridulatory organ on the cheliped (Guinot-Dumortier & Dumortier, I960; Dumortier, 1963a). A review of the literature on sound pro duction and perception by this genus has been given by Horch & Salmon (1969). They reported that Ocypode quadrata (Fabricius, 1787), unlike the closely related fiddler crab, Uca pugilator (Bosc, 1802), could perceive high frequency air borne sounds. Both species, however, are sensitive to substrate vibrations extending to the low kHz range of frequencies. Subsequent work showed that other species of Ocypode responded to both air and substrate borne sounds, and identified the receptor responsible for this sensitivity as Barth's myochordotonal organ (Horch, 1971; Horch & Salmon, 1972; Horch, 1974). As part of this work, field studies were done on the acoustic behavior of Ocypode ceratophthalmus (Pallas, 1772) at Eniwetok, Marshall Islands (Horch & Salmon, 1969). These studies indicated that O. ceratophthalmus there produces two kinds of sounds: rapping and rasping. The former sound, apparently similar to the knocking sounds reported by Hughes (1966), is believed to be produced by rapping of the major cheliped on the sand. The latter sound, because of its temporal structure, is believed to be stridulatory in nature (Barrass, 1963a, b;

Barth's myochordotonal organ as an acoustic sensor in the ghost crab, Ocypode.

Nachweis des Barth'schen Myochordotonal-Organs bei der KrabbeOcypode, als sensorieller Apparat fur hochfrequente, akustische Signale.

An organ for hearing and vibration sense in the ghost crab Ocypode

1. The sensory basis of sound and vibration perception has been studied neurophysiologically in the ghost crab Ocypode. Experiments were carried out both on neural responses from the brains of intact animals and on nerve responses recorded from isolated walking legs. 2. Hearing curves for two species of Ocypode from about 800 Hz to 3000 Hz showed maximum sensitivities in the 1–2 kHz band. 3. The substratum vibration sensitivity curve for Ocypode ceratophthalmus extended to 5000 Hz. 4. Synchrony between the response and the stimulus was seen for low frequency vibrations up to 600–800 Hz. 5. Sensitivity to high frequency vibrations and sounds was localized in Barth's myochordotonal organ in the merus of each walking leg. 6. This system could be used for conspecific call detection, and may provide sufficient information to the animals for orientation to acoustically signalling individuals.

Sensory and motor interaction in the locomotor reflexes of crabs.

ABSTRACT Proprioceptive reflexes involved in control of the mero-carpopodite (MC) joint in walking legs of Cancer magister are mediated by four groups of sensory cells: two cell groups (myochordotonal organs), located proximally in the leg segment, which are associated with a receptor muscle and come under efferent control, and two cell groups (MC organs) located distally which signal joint position and movement but are independent of efferent control. Resistance reflexes, which oppose passive movements of the joint, are evoked by both types of proprioceptive organs. Reflexes evoked by the MC organs are maximally effective at the extremes of joint position. Reciprocal inhibition of antagonistic muscle groups appears to occur entirely at synapses within the central nervous system. Efferent control of the receptor muscle comes under the influence of both the myochordotonal and MC organs. The reflexes evoked by the MC organs on the receptor muscles are similar to those which impinge on the main flexor. The myochordotonal organ excites the receptor muscle on joint movements away from the rest position. Interaction of input from the two types of sense organs provides the system with a dynamically determined reference point for the basic postural position. This may be altered by efferent control of the receptor muscle. Reflexes evoked by both types of proprioceptive organ spread to the other walking legs, but are more labile than reflexes to the same leg.

Proprioception by chordotonal organs in the mero-carpopodite and carpo-propodite joints of Carcinus maenas legs

1. 1. Both chordotonal receptor organs, MC1 and MC2, in the merocarpopodite joint in walking legs of the crab are stretched by flexion of this joint, whereas CP1 and CP2 are stretched by opposite movements of the carpopropodite joint, namely production and reduction, respectively. 2. 2. Afferent impulses have been recorded extracellularly from the whole sensory nerve and isolated fibres from each receptor, in response to (a) passive movement of the joint containing the organ, and (b) stretching and releasing the partially or completely excised receptor. 3. 3. Unidirectional movement and position fibres for relaxation (release) of the receptor—or the corresponding joint movement—were recorded in good numbers in all four sensory nerves. 4. 4. The nerves from MC1 also contained many movement and position fibres for receptor stretch—or joint flexion; while stretch sensitive movement and probably also position fibres are present in CP1 nerves, but are less common than relaxation fibres. In the six MC2 and six CP2 nerves studied, however, stretch sensitive fibres were not found. 5. 5. Correlations between the gross morphology and attachments of these receptors, the fine structure of their scolopidia, and their afferent responses are noted. The differentiation between ciliary adn paraciliary distal processes is not adequate to explain differential direction sensitivity. The reflex function of MC1 and MC2 and the myochordotonal organ in the base of the meropodite are considered.

Muscle fibres and efferent nerves in a crustacean receptor muscle

ABSTRACT The accessory flexor muscle of the crab myochordotonal organ consists of two kinds of muscle-fibres. In one type the fibrillar material has a uniform punctate appearance in cross-section. The Z bands are often broken across the fibre width and are spaced 2 to 3μapart. These resemble the ‘Fibrillenstruktur’ muscle of vertebrates. In the second fibre type the fibrillar material appears as large clumps in cross-section and it is often difficult to distinguish the outlines of individual fibres. The sarcomere length is 10 to 12μ. These resemble the ‘Felderstruktur’ muscle of vertebrates. Two types of expanded structures are seen in conjunction with the two efferent neurones innervating this muscle. With fresh material under phase microscopy one type appears as a 20 by 40μrectangular plaque containing vacuoles as well as dark clumps and granules. The other kind of enlargement consists of a group of spheres giving the appearance of a grape cluster and measuring 40 μin its greatest dimension. It is suggested that these expanded structures may be associated with efferent nerve terminations in this muscle.

The crustacean myochordotonal organ as a proprioceptive system

1. 1. In the meropodite of the walking legs of the crab Cancer magister Dana, the myochordotonal organ system consists of a specialized receptor muscle with associated elastic strands and a group of approximately forty bipolar neurons. This system provides proprioceptive information about action of the mero-carpopodite (MC) joint. The 6 mm length change in the receptor muscle caused by full joint movement is reduced 22 : 1 at the site of the sensory neurons by the elaborate mechanical suspension of the system. 2. 2. Electrophysiological recording from the sensory neurons discloses (1) movement receptors active during joint displacement and (2) position receptors which are sensitive to different static positions and relatively insensitive to the phasic component of joint action. The movement receptors are unidirectional with a given receptor responding to either flexion or extension of the MC joint. A single movement receptor responds only over a fraction of the full joint range and the composite input from many different receptors is required to cover the complete joint movement. Movement receptors increase their discharge rate with increasing velocity of joint movement. 3. 3. The position receptors fire at a different average frequency for each static position. A single unit also responds only over a fraction of the full joint range. 4. 4. Direct stretching or relaxation of the accessory flexor muscle can mimic the response of the sense cells evoked by activity of the MC joint. The accessory flexor muscle serves primarily a sensory role analogous to the intrafusal muscle fibers of the vertebrate muscle spindle.