*My biology project*
1.1 Information about Insect
Insects (Class Insecta) are a major group of arthropods and the most diverse group of animals on the Earth, with over a million described species, more than all other animal groups combined. Insects may be found in nearly all environments on the planet, although only a small number of species occur in the oceans where crustaceans tend to predominate instead. There are approximately 5,000 dragonfly species, 2,000 praying mantis, 20,000 grasshopper, 170,000 butterfly and moth, 120,000 fly, 82,000 true bug, 360,000 beetle, and 110,000 bee, wasp and ant species described to date. Estimates of the total number of current species, including those not yet known to science, range from two million to fifty million, with newer studies favouring a lower figure of about six to ten million.
1.2 Morphology
Insects possess segmented bodies supported by an exoskeleton, a hard outer covering made mostly of chitin. The segments of the body are organized into three regions, or tagmata; a head, a thorax, and an abdomen. The head supports a pair of sensory antennae, a pair of compound eyes, one to three simple eyes ("ocelli") and three sets of variously modified appendages that form the mouthparts. The thorax has six legs (one pair each for the prothorax, mesothorax and the metathorax segments making up the thorax) and two or four wings (if present in the species). The abdomen (made up of eleven segments some of which may be reduced or fused) has most of the digestive, respiratory, excretory and reproductive internal structures.
1.3 Nervous system
Their nervous system can be divided into a brain and a ventral nerve cord. The head capsule (made up of six fused segments) has six pairs of ganglia. The first three pairs are fused into the brain, while the three following pairs are fused into a structure called the subesophageal ganglion. The thoracic segments have one ganglion on each side, which are connected into a pair, one pair per segment. This arrangement is also seen in the abdomen but only in the first eight segments. Many species of insects have reduced numbers of ganglia due to fusion or reduction. Some cockroaches have just six ganglia in the abdomen, whereas the wasp Vespa crabro has only two in the thorax and three in the abdomen. And some, like the house fly Musca domestica, have all the body ganglia fused into a single large thoracic ganglion.
1.4 Respiration and circulation
Insect respiration is accomplished without lungs, but instead insects possess a system of internal tubes and sacs through which gases either diffuse or are actively pumped, delivering oxygen directly to body tissues (see Invertebrate trachea). Since oxygen is delivered directly, the circulatory system is not used to carry oxygen, and is therefore greatly reduced; it has no closed vessels (i.e., no veins or arteries), consisting of little more than a single, perforated dorsal tube which pulses peristaltically, and in doing so helps circulate the hemolymph inside the body cavity.
1.5 Exoskeleton
Most higher insects have two pairs of wings located on the second and third thoracic segments. Insects are the only invertebrates to have developed flight, and this has played an important part in their success. The winged insects, and their wingless relatives, make up the subclass Pterygota. Insect flight is not very well understood, relying heavily on turbulent aerodynamic effects. The primitive insect groups use muscles that act directly on the wing structure. The more advanced groups making up the Neoptera have foldable wings and their muscles act on the thorax wall and power the wings indirectly. These muscles are able to contract multiple times for each single nerve impulse, allowing the wings to beat faster than would ordinarily be possible (see insect flight). Their outer skeleton, the cuticle, is made up of two layers; the epicuticle which is a thin and waxy water resistant outer layer and contains no chitin, and another layer under it called the procuticle. This is chitinous and much thicker than the epicuticle and has two layers, the outer being 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 others in a sandwich pattern, while the exocuticle is rigid and sclerotized. The exocuticle is greatly reduced in many soft-bodied insects, especially the larval stages (e.g., caterpillars).
1.6 Development
Most insects hatch from eggs, but others are ovoviviparous or viviparous, and all undergo a series of moults as they develop and grow in size. This manner of growth is necessitated by the inelastic exoskeleton. Moulting is a process by which the individual escapes the confines of the exoskeleton in order to increase in size, then grows a new and larger outer covering. In some insects, the young are called nymphs and are similar in form to the adult except that the wings are not developed until the adult stage. This is called incomplete metamorphosis and insects showing this are termed hemimetabolous. Holometabolous insects show complete metamorphosis, which distinguishes the Endopterygota and includes many of the most successful insect groups. In these species, an egg hatches to produce a larva, which is generally worm-like in form, and can be divided into five different forms; eruciform (caterpillar-like), scarabaeiform (grublike), campodeiform (elongated, flattened, and active), elateriform (wireworm-like) and vermiform (maggot-like). The larva grows and eventually becomes a pupa, a stage sealed within a cocoon in some species. There are three types of pupae; obtect (the pupa is compact with the legs and other appendages enclosed), exarate (where the pupa has the legs and other appendages free and extended) and coarctate (where the pupa develops inside the larval skin). In the pupal stage, the insect undergoes considerable change in form to emerge as an adult, or imago. Butterflies are an example of an insect that undergoes complete metamorphosis. Some insects have even evolved hypermetamorphosis. Some insects (parastic wasps) show polyembryony where a single fertilized egg can divide into many and in some cases thousands of separate embryos. Other developmental and reproductive variations include haplodiploidy, polymorphism, paedomorphosis (metathetely and prothetely), sexual dimorphism, parthenogenesis and more rarely hermaphroditism.
1.7 Locomotion
• Flight
Insects are the only group of invertebrates to have developed flight.In addition to powered flight, many of the smaller insects are also dispersed by winds. In the Carboniferous age, some of the Meganeura dragonflies had as much as a 50 cm (20 in) wide wingspan. The appearance of gigantic insects has been found to be consistent with high atmospheric oxygen.
• Walking
Many adult insects use six legs for walking and have adopted a tripedal gait.The legs are used in alternate triangles touching the ground. For the first step the middle right leg and the front and rear left legs are in contact with the ground and move the insect forward, whilst the front and rear right leg and the middle left leg are lifted and moved forward to a new position. When they touch the ground to form a new stable triangle the other legs can be lifted and brought forward in turn and so on. A few insects have evolved to walk on the surface of the water, especially the bugs of the family, Gerridae, also known as water striders.
• Swimming
The backswimmer Notonecta glauca underwater, showing the paddle like hindleg adaptationA large number of insects live either parts or the whole of their lives underwater.Many of these species have adaptations to help in locomotion under water. The water beetles and water bugs have legs adapted into paddle like structures. Some species like the water striders are capable of walking on the surface of water. Some others such as the Rove beetle Velia are known to emit salivary secretions that reduce surface tension making it possible for them to move on the surface of water.
1.8 Insect Classification and Identification
It is necessary to classify insects so that we can organize what we know about them and determine their relationships with other insects. For example, all members of a particular species will feed on similar foods, have similar developmental characteristics, and exist in similar environments. Most often, insect species are classified based on similarities in appearance (morphology). The flies, for example, can be distinguished and classified separately from all other winged insects because they have only one pair of wings. The hierarchy used to classify the diamondback moth, a worldwide pest of crucifers, is as follows:
Phylum - ArthropodaClass - InsectaOrder - LepidopteraFamily - PlutellidaeGenus - PlutellaSpecies - Plutella xylostella
This universal method is used to prevent confusion among geographic regions of the world. Consequently, Plutella xylostella refers to the same insect species in the United States as it does in Asia or anywhere else in the world. Common names, however, can vary from one location to another.
2.0 Objective
I. To obtain undamaged and representative specimens, usually in a preserved form.
II. To understand the processes that preserve insects in the specimen box.
III. To identify their scientific names and classifications of every collected insects.
IV. To appreciate the biological information that can be gather from these specimens.
3.0 Methodology
3.1 Materials
• Insects that have complete parts of its body and large enough to be examined.
• Pin
• Specimen box
3.2 Methods
I. Insects are collected.
II. Those insects are put into the lab oven with temperature, 38 degree celcius and let it dry for 2 days.
III. After 2 days, those insects are brush with ethanol to soften the body part.IV. After a few days, take the insects from the oven and put it in the specimen box and arranged it properly.V. Pin the insects to hold it inside the specimen box and each insect labeled.
to be continued....
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Very left above is the stim fish made by my aunty... very delicious I tell you. Ahax.. DUn underestimested by its look.. you have to try it...jpg)
" Yang bermaksud, Sahaja aku berpuasa sebulan pada bulan Ramadan bagi tahun ini kerana Allah Taala "
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