morphology and anatomy of cockroach pdf

Morphology and anatomy of cockroach pdf

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Insect morphology


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Insect morphology

Insect morphology is the study and description of the physical form of insects. The terminology used to describe insects is similar to that used for other arthropods due to their shared evolutionary history.

Three physical features separate insects from other arthropods: they have a body divided into three regions called tagmata head, thorax, and abdomen , have three pairs of legs, and mouthparts located outside of the head capsule.

It is this position of the mouthparts which divides them from their closest relatives, the non-insect hexapods , which includes Protura , Diplura , and Collembola. There is enormous variation in body structure amongst insect species. Individuals can range from 0. These modifications allow insects to occupy almost every ecological niche on the planet, except the deep ocean.

This article describes the basic insect body and some of the major variations of the different body parts; in the process it defines many of the technical terms used to describe insect bodies. Insects, like all arthropods, have no interior skeleton; instead, they have an exoskeleton , a hard outer layer made mostly of chitin which protects and supports the body.

The insect body is divided into three parts : the head, thorax , and abdomen. The insect outer skeleton, the cuticle , is made up of two layers; the epicuticle , which is a thin, waxy, water-resistant outer layer and contains no chitin, and the layer under it called the procuticle.

This is chitinous and much thicker than the epicuticle and has two layers, the outer is the exocuticle while the inner is the endocuticle. The tough and flexible endocuticle is built from numerous layers of fibrous chitin and proteins, criss-crossing each other in a sandwich pattern, while the exocuticle is rigid and sclerotized.

Chemically, chitin is a long-chain polymer of a N-acetylglucosamine , a derivative of glucose. In its unmodified form, chitin is translucent, pliable, resilient and quite tough.

In arthropods , however, it is often modified, becoming embedded in a hardened proteinaceous matrix, which forms much of the exoskeleton. In its pure form, it is leathery, but when encrusted in calcium carbonate , it becomes much harder. From the embryonic stages itself, a layer of columnar or cuboidal epithelial cells gives rise to the external cuticle and an internal basement membrane.

The majority of insect material is held in the endocuticle. The cuticle provides muscular support and acts as a protective shield as the insect develops. However, since it cannot grow, the external sclerotised part of the cuticle is periodically shed in a process called "moulting".

As the time for moulting approaches, most of the exocuticle material is reabsorbed. In moulting, first the old cuticle separates from the epidermis apolysis. Enzymatic moulting fluid is released between the old cuticle and epidermis, which separates the exocuticle by digesting the endocuticle and sequestering its material for the new cuticle. When the new cuticle has formed sufficiently, the epicuticle and reduced exocuticle are shed in ecdysis.

The four principal regions of an insect body segment are: tergum or dorsal, sternum or ventral and the two pleura or laterals. Hardened plates in the exoskeleton are called sclerites, which are subdivisions of the major regions - tergites, sternites and pleurites, for the respective regions tergum, sternum, and pleuron. The head in most insects is enclosed in a hard, heavily sclerotized, exoskeletal head capsule'. The main exception is in those species whose larvae are not fully sclerotised, mainly some holometabola; but even most unsclerotised or weakly sclerotised larvae tend to have well sclerotised head capsules, for example the larvae of Coleoptera and Hymenoptera.

The larvae of Cyclorrhapha however, tend to have hardly any head capsule at all. The head capsule bears most of the main sensory organs, including the antennae, ocelli, and the compound eyes. It also bears the mouthparts. In the adult insect the head capsule is apparently unsegmented, though embryological studies show it to consist of six segments that bear the paired head appendages, including the mouthparts, each pair on a specific segment. Of all the insect orders, Orthoptera most conveniently display the greatest variety of features found in the heads of insects, including the sutures and sclerites.

In prognathous insects, the vertex is not found between the compound eyes, but rather, where the ocelli are normally found. In some species, this region is modified and assumes a different name. The ecdysial suture is made of the coronal, frontal, and epicranial sutures plus the ecdysial and cleavage lines, which vary among different species of insects.

The ecdysial suture is longitudinally placed on the vertex and separates the epicranial halves of the head to the left and right sides. Depending on the insect, the suture may come in different shapes: like either a Y, U, or V. Those diverging lines that make up the ecdysial suture are called the frontal or frontogenal sutures. Not all species of insects have frontal sutures, but in those that do, the sutures split open during ecdysis , which helps provide an opening for the new instar to emerge from the integument.

The frons is that part of the head capsule that lies ventrad or anteriad of the vertex. The frons varies in size relative to the insect, and in many species the definition of its borders is arbitrary, even in some insect taxa that have well-defined head capsules. In most species, though, the frons is bordered at its anterior by the frontoclypeal or epistomal sulcus above the clypeus.

Laterally it is limited by the fronto-genal sulcus, if present, and the boundary with the vertex, by the ecdysial cleavage line, if it is visible. If there is a median ocellus, it generally is on the frons, though in some insects such as many Hymenoptera, all three ocelli appear on the vertex.

A more formal definition is that it is the sclerite from which the pharyngeal dilator muscles arise, but in many contexts that too, is not helpful. The clypeus is a sclerite between the face and labrum, which is dorsally separated from the frons by the frontoclypeal suture in primitive insects. The clypeogenal suture laterally demarcates the clypeus, with the clypeus ventrally separated from the labrum by the clypeolabral suture.

The clypeus differs in shape and size, such as species of Lepidoptera with a large clypeus with elongated mouthparts. The cheek or gena forms the sclerotized area on each side of the head below the compound eyes extending to the gular suture.

Like many of the other parts making up the insect's head, the gena varies among species, with its boundaries difficult to establish.

For example, in dragonflies and damselflies , it is between the compound eyes, clypeus, and mouthparts. The postgena is the area immediately posteriad, or posterior or lower on the gena of pterygote insects , and forms the lateral and ventral parts of the occipital arch. The occipital arch is a narrow band forming the posterior edge of the head capsule arching dorsally over the foramen. The subgenal area is usually narrow, located above the mouthparts; this area also includes the hypostoma and pleurostoma.

The posterior wall of the head capsule is penetrated by a large aperture, the foramen. Through it pass the organ systems, such as nerve cord , esophagus , salivary ducts , and musculature , connecting the head with the thorax. On the posterior aspect of the head are the occiput , postgena , occipital foramen , posterior tentorial pit , gula, postgenal bridge , hypostomal suture and bridge , and the mandibles , labium , and maxilla. The occipital suture is well founded in species of Orthoptera, but not so much in other orders.

Where found, the occipital suture is the arched, horseshoe-shaped groove on the back of the head, ending at the posterior of each mandible. The postoccipital suture is a landmark on the posterior surface of the head, and is typically near the occipital foremen. In pterygotes, the postocciput forms the extreme posterior, often U-shaped, which forms the rim of the head extending to the postoccipital suture.

In pterygotes, such as those of Orthoptera, the occipital foramen and the mouth are not separated. The three types of occipital closures, or points under the occipital foramen that separate the two lower halves of the postgena, are: the hypostomal bridge, the postgenal bridge, and the gula.

The hypostomal bridge is usually found in insects with hypognathous orientation. The postgenal bridge is found in the adults of species of higher Diptera and aculeate Hymenoptera , while the gula is found on some Coleoptera , Neuroptera , and Isoptera , which typically display prognathous-oriented mouthparts. Most insects have one pair of large, prominent compound eyes composed of units called ommatidia ommatidium , singular , possibly up to 30, in a single compound eye of, for example, large dragonflies.

This type of eye gives less resolution than eyes found in vertebrates, but it gives acute perception of movement and usually possesses UV- and green sensitivity and may have additional sensitivity peaks in other regions of the visual spectrum.

Often an ability to detect the E-vector of polarized light exists polarization of light. The image perceived is a combination of inputs from the numerous ommatidia, located on a convex surface, thus pointing in slightly different directions.

Because the individual lenses are so small, the effects of diffraction impose a limit on the possible resolution that can be obtained assuming they do not function as phased arrays. This can only be countered by increasing lens size and number. To see with a resolution comparable to our simple eyes, humans would require compound eyes that would each reach the size of their heads.

Compound eyes fall into two groups: apposition eyes, which form multiple inverted images, and superposition eyes, which form a single erect image.

Antennae , sometimes called "feelers", are flexible appendages located on the insect's head which are used for sensing the environment. Insects are able to feel with their antennae because of the fine hairs setae that cover them. The number of segments in an antenna varies considerably amongst insects, with higher flies having only segments, [21] while adult cockroaches can have over The remaining antennal segments or flagellomeres are called the flagellum.

The insect mouthparts consist of the maxilla, labium, and in some species, the mandibles. The mandibles jaws are a highly sclerotized pair of structures that move at right angles to the body, used for biting, chewing, and severing food.

The maxillae are paired structures that can also move at right angles to the body and possess segmented palps. The labium lower lip is the fused structure that moves longitudinally and possesses a pair of segmented palps. The mouthparts, along with the rest of the head, can be articulated in at least three different positions: prognathous, opisthognathous, and hypognathous.

In species with prognathous articulation, the head is positioned vertically aligned with the body, such as species of Formicidae ; while in a hypognathous type, the head is aligned horizontally adjacent to the body.

An opisthognathous head is positioned diagonally, such as species of Blattodea and some Coleoptera. Haustellate mouthparts are used for sucking liquids and can be further classified by the presence of stylets , which include piercing-sucking, sponging, and siphoning.

The stylets are needle-like projections used to penetrate plant and animal tissues. The stylets and the feeding tube form the modified mandibles, maxilla, and hypopharynx. Mandibular mouthparts are found in species of Odonata , adult Neuroptera , Coleoptera , Hymenoptera , Blattodea , Orthoptera , and Lepidoptera. However, most adult Lepidoptera have siphoning mouthparts, while their larvae commonly called caterpillars have mandibles. The labrum is a broad lobe forming the roof of the preoral cavity, suspended from the clypeus in front of the mouth and forming the upper lip.

The labrum is raised away from the mandibles by two muscles arising in the head and inserted medially into the anterior margin of the labrum. It is closed against the mandibles in part by two muscles arising in the head and inserted on the posterior lateral margins on two small sclerites, the tormae, and, at least in some insects, by a resilin spring in the cuticle at the junction of the labrum with the clypeus.

However, recent studies of the embryology, gene expression, and nerve supply to the labrum show it is innervated by the tritocerebrum of the brain, which is the fused ganglia of the third head segment. This is formed from fusion of parts of a pair of ancestral appendages found on the third head segment, showing their relationship.

Chewing insects have two mandibles, one on each side of the head. The mandibles are positioned between the labrum and maxillae. The mandibles cut and crush food, and may be used for defense; generally, they have an apical cutting edge, and the more basal molar area grinds the food.


Insect morphology is the study and description of the physical form of insects. The terminology used to describe insects is similar to that used for other arthropods due to their shared evolutionary history. Three physical features separate insects from other arthropods: they have a body divided into three regions called tagmata head, thorax, and abdomen , have three pairs of legs, and mouthparts located outside of the head capsule. It is this position of the mouthparts which divides them from their closest relatives, the non-insect hexapods , which includes Protura , Diplura , and Collembola. There is enormous variation in body structure amongst insect species. Individuals can range from 0.

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Hebardina concinna is a domestic pest and potential vector of pathogens throughout East and Southeast Asia, yet identification of this species has been difficult due to a lack of diagnostic morphological characters, and to uncertainty in the relationship between macroptyrous long-winged and brachypterous small-winged morphotypes. In insects male genital structures are typically species-specific and are frequently used to identify species. However, male genital structures in H. We collected 15 putative H. These confirmed that both morphotypes of both sexes are the same species. We then dissected male genitalia and compared genital structures from macropterous and brachypterous individuals, which we showed to be identical, and present here for the first time a detailed description of H. We also present a complete re-description of the morphological characters of this species, including both wing morphs.

A cockroach has three main body parts, namely the head, thorax, and abdomen. It also has a hard outer-body covering known as the exoskeleton. This.

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About cockroach morphology and anatomy. Digestive System. Frogs are carnivorous tailless amphibians which are widely found in India.

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Multiple Choice Questions form important part of competitive exams and NEET exam and if practiced properly can help you to get higher rank. Cockroach show characteristic features in segmentation, symmentry and body organization. Morphology - Body is covered with hard chitinous exoskeleton. Body is divisible into three regions.

Youtube - Hindi. Class 11 Biology Structural Organisation In Animals Morphology and anatomy of cockroach Morphology and anatomy of cockroach Cockroaches are brown or black bodied animals that are included in class Insecta of Phylum Arthropoda. They have long antenna, legs and flat extension of the upper body wall that conceals head. They are pests because they destroy food and contaminate it with their smelly excreta and also transmit various types of bacterial diseases. Morphology The adults of the common species of cockroach, Periplaneta americana are about mm long with wings extend beyond the tip of the abdomen in males.

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Periplanata Americana, a common species of cockroach. Exoskeleton is thick and hard and is made up of calcareous plates called sclerites. There are ten segments are present on dorsal side which is called tergum and ventral side is known as sternum. It protects the body of cockroach from loss of water and provides rigidity and surface for the attachment of body muscles. They cover the hind wings and are protective in function. These are dark, stiff, opaque and leathery.

You are commenting using your WordPress. You are commenting using your Google account. You are commenting using your Twitter account. You are commenting using your Facebook account. Notify me of new comments via email. Notify me of new posts via email. September 14, September 14, preetipareek28gmailcom.

Periplaneta americana is the common species of cockroach. An adult cockroach is about 34 — 53 mm long. Wings extend beyond the tip of the abdomen in males. The body is segmented into three distinct regions, viz. The whole body is covered by a brown coloured hard exoskeleton which is made up of chitin. In each segment, the exoskeleton has hardened plates; called sclerites.

morphology and anatomy of cockroach class 11 pdf

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