Sensillum

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A sensillum (plural sensilla) is an arthropod sensory organ protruding from the cuticle of exoskeleton, or sometimes lying within or beneath it. Sensilla appear as small hairs or pegs over an individual's body. Inside each sensillum there are two to four sensory neurons. These neurons, or receptors, gather information about environment the arthropod is in: [1]

Most sensilla are specially shaped according to the type of information they are gathering.

In spiders, slit sensilla are used to detect substrate vibrations, while trichobothria are used to detect air-borne vibrations. [2]

Chemoreceptors

Chemo-reception is one of the most dominant senses in the insect kingdom. Many arthropods use chemical signals to locate food, shelter and mates.

Other invertebrates have similar sensory organs also referred to as sensilla; these consist of various papillae or ciliated areas of the cuticle connected to sensory neurons and occur in velvet worms, tardigrades and leeches. [3]

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<span class="mw-page-title-main">Halteres</span> Pair of small club-shaped insect organs

Halteres are a pair of small club-shaped organs on the body of two orders of flying insects that provide information about body rotations during flight. Insects of the large order Diptera (flies) have halteres which evolved from a pair of ancestral hindwings, while males of the much smaller order Strepsiptera (stylops) have halteres which evolved from a pair of ancestral forewings.

<span class="mw-page-title-main">Antenna (biology)</span> Paired appendages used for sensing in arthropods

Antennae, sometimes referred to as "feelers", are paired appendages used for sensing in arthropods.

A chemoreceptor, also known as chemosensor, is a specialized sensory receptor which transduces a chemical substance to generate a biological signal. This signal may be in the form of an action potential, if the chemoreceptor is a neuron, or in the form of a neurotransmitter that can activate a nerve fiber if the chemoreceptor is a specialized cell, such as taste receptors, or an internal peripheral chemoreceptor, such as the carotid bodies. In physiology, a chemoreceptor detects changes in the normal environment, such as an increase in blood levels of carbon dioxide (hypercapnia) or a decrease in blood levels of oxygen (hypoxia), and transmits that information to the central nervous system which engages body responses to restore homeostasis.

A mechanoreceptor, also called mechanoceptor, is a sensory receptor that responds to mechanical pressure or distortion. Mechanoreceptors are innervated by sensory neurons that convert mechanical pressure into electrical signals that, in animals, are sent to the central nervous system.

Johnston's organ is a collection of sensory cells found in the pedicel of the antennae in the class Insecta. Johnston's organ detects motion in the flagellum. It consists of scolopidia arrayed in a bowl shape, each of which contains a mechanosensory chordotonal neuron. The number of scolopidia varies between species. In homopterans, the Johnston's organs contain 25 - 79 scolopidia. The presence of Johnston's organ is a defining characteristic which separates the class Insecta from the other hexapods belonging to the group Entognatha. Johnston's organ was named after the physician Christopher Johnston, father of the physician and Assyriologist Christopher Johnston.

<span class="mw-page-title-main">Campaniform sensilla</span> Class of mechanoreceptors found in insects

Campaniform sensilla are a class of mechanoreceptors found in insects, which respond to local stress and strain within the animal's cuticle. Campaniform sensilla function as proprioceptors that detect mechanical load as resistance to muscle contraction, similar to mammalian Golgi tendon organs. Sensory feedback from campaniform sensilla is integrated in the control of posture and locomotion.

Chordotonal organs are stretch receptor organs found only in insects and crustaceans. They are located at most joints and are made up of clusters of scolopidia that either directly or indirectly connect two joints and sense their movements relative to one another. They can have both extero- and proprioceptive functions, for example sensing auditory stimuli or leg movement. The word was coined by Vitus Graber in 1882, though he interpreted them as being stretched between two points like a string, sensing vibrations through resonance.

<span class="mw-page-title-main">Tympanal organ</span> Hearing organ in insects

A tympanal organ is a hearing organ in insects, consisting of a membrane (tympanum) stretched across a frame backed by an air sac and associated sensory neurons. Sounds vibrate the membrane, and the vibrations are sensed by a chordotonal organ. Hymenoptera do not have a tympanal organ, but they do have a Johnston's organ.

Odorant-binding proteins (OBPs) are small soluble proteins secreted by auxiliary cells surrounding olfactory receptor neurons, including the nasal mucus of many vertebrate species and in the sensillar lymph of chemosensory sensilla of insects. OBPs are characterized by a specific protein domain that comprises six α-helices joined by three disulfide bonds. Although the function of the OBPs as a whole is not well established, it is believed that they act as odorant transporters, delivering the odorant molecules to olfactory receptors in the cell membrane of sensory neurons.

Insect physiology includes the physiology and biochemistry of insect organ systems.

<span class="mw-page-title-main">Arista (insect anatomy)</span> Bristle arising from the third antennal segment of an insect

In insect anatomy the arista is a simple or variously modified apical or subapical bristle, arising from the third antennal segment. It is the evolutionary remains of antennal segments, and may sometimes show signs of segmentation. These segments are called aristameres. The arista may be bare and thin, sometime appearing no more than a simple bristle; pubescent, covered in short hairs; or plumose, covered in long hairs.

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The sense of smell, or olfaction, is the special sense through which smells are perceived. The sense of smell has many functions, including detecting desirable foods, hazards, and pheromones, and plays a role in taste.

A sense is a biological system used by an organism for sensation, the process of gathering information about the world through the detection of stimuli. Although in some cultures five human senses were traditionally identified as such, many more are now recognized. Senses used by non-human organisms are even greater in variety and number. During sensation, sense organs collect various stimuli for transduction, meaning transformation into a form that can be understood by the brain. Sensation and perception are fundamental to nearly every aspect of an organism's cognition, behavior and thought.

<span class="mw-page-title-main">Haller's organ</span> Sensory organ on the front legs of ticks

Haller's organ is a complex sensory organ possessed by hard and soft ticks. Not found outside of Acari, it is proposed to function like the chemosensation of insect antennae, but is structurally different. Ticks, being obligate parasites, must find a host in order to survive. Bloodmeals are necessary for completion of the life cycle, including reproduction and ontogenetic development. First described in 1881, it was named for its discoverer, Haller. While Haller initially proposed it was involved in auditory sensation, this was rejected in favor of olfactory sensation by 1905. This theory was supported by Lee's behavioral studies as early as 1948.

<span class="mw-page-title-main">Subgenual organ</span>

The subgenual organ is an organ in insects that is involved in the perception of sound. The name refers to the location of the organ just below the knee in the tibia of all legs in most insects.

<span class="mw-page-title-main">Insect olfaction</span> Function of chemical receptors

Insect olfaction refers to the function of chemical receptors that enable insects to detect and identify volatile compounds for foraging, predator avoidance, finding mating partners and locating oviposition habitats. Thus, it is the most important sensation for insects. Most important insect behaviors must be timed perfectly which is dependent on what they smell and when they smell it. For example, olfaction is essential for locating host plants and hunting prey in many species of insects, such as the moth Deilephila elpenor and the wasp Polybia sericea, respectively.

Hair-plates are a type of proprioceptor found in the folds of insect joints. They consist of a cluster of hairs, in which each hair is innervated by a single mechanosensory neuron. Functionally, hair-plates operate as "limit-detectors" by signaling the extreme ranges of motion of a joint.

Single sensillum recording (SSR) is a form of extracellular electrophysiology. This technique measures action potentials, generated from olfactory sensory neurons (OSNs), through a single sensilla on an insects' antennae. These sensillum are hair-like structures that protrude through the cuticle as well as several other auxiliary and sensory cells.

References

  1. Steinbrecht, Rudolf Alexander (2007). "Structure and Function of Insect Olfactory Sensilla". Ciba Foundation Symposium 200 - Olfaction in Mosquito-Host Interactions. Novartis Foundation Symposia. Vol. 200. pp. 158–183. doi:10.1002/9780470514948.ch13. ISBN   9780470514948. ISSN   1935-4657. PMID   8894297.
  2. Zhang, Changchao; Zhang, Junqiu; Chen, Daobing; Meng, Xiancun; Liu, Linpeng; Wang, Kejun; Jiao, Zhibin; Sun, Tao; Wang, Dakai; Niu, Shichao; Han, Zhiwu; Ren, Luquan (1 September 2020). "Crack-based and Hair-like Sensors Inspired from Arthropods: A Review". Journal of Bionic Engineering. 17 (5): 867–898. doi: 10.1007/s42235-020-0092-6 . ISSN   2543-2141. S2CID   225398670.
  3. Ruppert, Edward E.; Fox, Richard, S.; Barnes, Robert D. (2004). Invertebrate Zoology, 7th edition. Cengage Learning. p. 508. ISBN   978-81-315-0104-7.{{cite book}}: CS1 maint: multiple names: authors list (link)

[1]

  1. Altner, Helmut; Prillinger, Linde (1980-01-01), Bourne, G. H.; Danielli, J. F. (eds.), "Ultrastructure of Invertebrate Chemo-, Thermo-, and Hygroreceptors and Its Functional Significance", International Review of Cytology, Academic Press, vol. 67, pp. 69–139, retrieved 2022-08-13