Arthropods in the context of Chitin

The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain, spinal cord and retina. The CNS is so named because the brain integrates the received information and coordinates and influences the activity of all parts of the bodies of bilaterally symmetric and triploblastic animals—that is, all multicellular animals except sponges and diploblasts. It is a structure composed of nervous tissue positioned along the rostral (nose end) to caudal (tail end) axis of the body and may have an enlarged section at the rostral end which is a brain. Only arthropods, cephalopods and vertebrates have a true brain, though precursor structures exist in onychophorans, gastropods and lancelets.

The rest of this article exclusively discusses the vertebrate central nervous system, which is radically distinct from all other animals.

Dichlorodiphenyltrichloroethane (DDT) is a colorless, tasteless, and almost odorless crystalline chemical compound, an organochloride. Originally developed as an insecticide, it became infamous for its environmental impacts. DDT was first synthesized in 1874 by the Austrian chemist Othmar Zeidler. DDT's insecticidal action was discovered by the Swiss chemist Paul Hermann Müller in 1939. DDT was used in the second half of World War II to limit the spread of the insect-borne diseases malaria and typhus among civilians and troops. Müller was awarded the Nobel Prize in Physiology or Medicine in 1948 "for his discovery of the high efficiency of DDT as a contact poison against several arthropods". The WHO's anti-malaria campaign of the 1950s and 1960s relied heavily on DDT and the results were promising, though there was a resurgence in developing countries afterwards.

An animal product is any material derived from the body of a non-human animal or their excretions. Examples are meat, fat, blood, milk, eggs, honey, and lesser known products, such as isinglass, rennet, and cochineal.

The word animals includes all species in the biological kingdom Animalia, except humans. This includes, for example, tetrapods, arthropods, and mollusks. Generally, products made from decomposed animals, such as petroleum, or crops grown in soil fertilized with animal remains or manure are not characterized as animal products. Products sourced from humans (e.g. breast milk) are not typically classified as animal products.

The birds-of-paradise are members of the family Paradisaeidae of the order Passeriformes. They are found mainly in New Guinea, as well as eastern Australia and the Moluccas. The family has 45 species in 17 genera. The members of this family are perhaps best known for the plumage of the males of the species, the majority of which are sexually dimorphic. The males of these species tend to have very long, elaborate feathers extending from the beak, wings, tail, or head. For the most part, they are confined to dense rainforest habitats. The diet of all species is dominated by fruit and to a lesser extent arthropods. The birds-of-paradise have a variety of breeding systems, ranging from monogamy to lek-type polygamy.

A number of species are threatened by hunting and habitat loss.

Breeding in the wild is the natural process of animal reproduction occurring in the natural habitat of a given species. This terminology is distinct from animal husbandry or breeding of species in captivity. Breeding locations are often chosen for very specific requirements of shelter and proximity to food; moreover, the breeding season is a particular time window that has evolved for each species to suit species anatomical, mating-ritual, or climatic and other ecological factors. Many species migrate considerable distances to reach the requisite breeding locations. Certain common characteristics apply to various taxa within the animal kingdom, which traits are often sorted among amphibians, reptiles, mammals, avafauna, arthropods and lower life forms.

The compound eyes of arthropods like insects, crustaceans and millipedes are composed of units called ommatidia (sg.: ommatidium). An ommatidium contains a cluster of photoreceptor cells surrounded by support cells and pigment cells. The outer part of the ommatidium is overlaid with a transparent cornea. Each ommatidium is innervated by one axon bundle (usually consisting of 6–9 axons, depending on the number of rhabdomeres) and provides the brain with one picture element. The brain forms an image from these independent picture elements. The number of ommatidia in the eye depends upon the type of arthropod and range from as low as five as in the Antarctic isopod Glyptonotus antarcticus, or a handful in the primitive Zygentoma, to around 30,000 in larger Anisoptera dragonflies and some Sphingidae moths.

Protichnites is an ichnogenus of trace fossil consisting of the imprints made by the walking activity of certain arthropods. It consists of two rows of tracks and a medial furrow between the two rows. This furrow, which may be broken, set at an angle, and of varying width and depth, is thought to be the result of the tail region contacting the substrate.

Proarticulata (also known as Dickinsoniomorpha) is a phylum of extinct, near-bilaterally symmetrical animals known from fossils found in the Ediacaran (Vendian) marine deposits, and dates to approximately 567 to 550 million years ago. The name comes from the Greek προ (pro-) = "before" and Articulata, i.e. prior to animals with true segmentation such as annelids and arthropods. This phylum was established by Mikhail A. Fedonkin in 1985 for such animals as Dickinsonia, Vendia, Cephalonega, Praecambridium and currently many other Proarticulata are described (see list).

Due to their simplistic morphology, their affinities and mode of life are subject to debate. They are almost universally considered to be metazoans, and due to possessing a clear central axis have been suggested to be stem-bilaterians. In the traditional interpretation, the Proarticulatan body is divided into transverse articulation (division) into isomers as distinct from the transverse articulation segments in annelids and arthropods, as their individual isomers occupy only half the width of their bodies, and are organized in an alternating pattern along the longitudinal axis of their bodies. In other words, one side is not the direct mirror image of its opposite (chirality). Opposite isomers of left and right side are located with displacement of half of their width. This phenomenon is described as the symmetry of gliding reflection. Some recent research suggests that some proarticulatans like Dickinsonia have genuine segments, and the isomerism is superficial and due to taphonomic distortion. However, other researchers dispute this. Displacement of left-right axis is known in bilaterians, notably lancelets.

Insect traps are used to monitor or directly reduce populations of insects or other arthropods, by trapping individuals and killing them. They typically use food, visual lures, chemical attractants and pheromones as bait and are installed so that they do not injure other animals or humans or result in residues in foods or feeds. Visual lures use light, bright colors and shapes to attract pests. Chemical attractants or pheromones may attract only a specific sex. Insect traps are sometimes used in pest management programs instead of pesticides but are more often used to look at seasonal and distributional patterns of pest occurrence. This information may then be used in other pest management approaches.

The trap mechanism or bait can vary widely. Flies and wasps are attracted by proteins. Mosquitoes and many other insects are attracted by bright colors, carbon dioxide, lactic acid, floral or fruity fragrances, warmth, moisture and pheromones. Synthetic attractants like methyl eugenol are very effective with tephritid flies.

Many species of arthropods (insects, arachnids, millipedes and centipedes) can bite or sting human beings. These bites and stings generally occur as a defense mechanism or during normal arthropod feeding. While most cases cause self-limited irritation, medically relevant complications include envenomation, allergic reactions, and transmission of vector-borne diseases.

Terrapins or water tortoises are a group of several species of aquatic reptile of the order Testudines living primarily in fresh or brackish tidal waters, but have the clawed feet of tortoises and not flippers of marine turtles. In American English, they are referred to as marsh, pond, or tide-water turtles, with some species called pond sliders as well. Whereas tortoises are almost strict herbivores and frugivores — largely feeding on flowers, grasses, leaves, and fallen fruit — a great many terrapins are mainly carnivorous — largely feeding on amphibians, arthropods, freshwater fish, and molluscs — though some are herbivores. Terrapins are identified primarily with the taxonomic family Emydidae, but do not form a single taxon and may not be closely related, with some belonging to the families Geoemydidae, Pelomedusidae, Podocnemididae, and Chelydridae. Though primarily aquatic, terrapins do relatively frequently come to land for many reasons, but particularly to warm up by basking in the sun.

An instar (/ˈɪnstɑːr/ , from the Latin īnstar 'form, likeness') is a developmental stage of arthropods, such as insects, which occurs between each moult (ecdysis) until sexual maturity is reached. Arthropods must shed the exoskeleton in order to grow or assume a new form. Differences between instars can often be seen in altered body proportions, colors, patterns, changes in the number of body segments or head width. After shedding their exoskeleton (moulting), the juvenile arthropods continue in their life cycle until they either pupate or moult again. The instar period of growth is fixed; however, in some insects, like the salvinia stem-borer moth, the number of instars depends on early larval nutrition. Some arthropods can continue to moult after sexual maturity, but the stages between these subsequent moults are generally not called instars.

For most insect species, an instar is the developmental stage of the larval forms of holometabolous (complete metamorphism) or nymphal forms of hemimetabolous (incomplete metamorphism) insects, but an instar can be any developmental stage including pupa or imago (the adult, which does not moult in insects).

Flesh is any aggregation of soft tissues of an organism. Various multicellular organisms have soft tissues that may be called "flesh". In mammals, including humans, flesh encompasses muscles, fats and other loose connective tissues, but sometimes excludes non-muscular organs (liver, lung, spleen, kidney) and typically discarded parts (hard tendon, brain tissue, intestines, etc.). More generally, it may be considered the portions of the body that are soft and delicate. In a culinary context, consumable animal flesh is called meat, while processed visceral tissues are known as offal.

In particular animal groups such as vertebrates, molluscs and arthropods, the flesh is distinguished from tougher body structures such as bone, shell and scute, respectively. In plants, the "flesh" is the juicy, edible structures such as the mesocarp of fruits and melons as well as soft tubers, rhizomes and taproots, as opposed to tougher structures like nuts and stems. In fungi, flesh refers to trama, the soft, inner portion of a mushroom, or fruit body.

The Argentine ant (Linepithema humile, formerly Iridomyrmex humilis) is an ant native to northern Argentina, Uruguay, Paraguay, Bolivia and southern Brazil. This invasive species was inadvertently introduced by humans on a global scale and has become established in many Mediterranean climate areas, including South Africa, New Zealand, Japan, Easter Island, Australia, the Azores, Europe, Hawaii, and the continental United States. Argentine ants are significant pests within agricultural and urban settings, and are documented to cause substantial harm to communities of native arthropods, vertebrates, and plants within their invaded range.

An insectarium is a live insect zoo, or a museum or exhibit of live insects. Insectariums often display a variety of insects and similar arthropods, such as spiders, beetles, cockroaches, ants, bees, millipedes, centipedes, crickets, grasshoppers, stick insects, scorpions, mantises and woodlice. Displays can focus on learning about insects, types of insects, their habitats, why they are important, and the work of entomologists, arachnologists, and other scientists that study terrestrial arthropods and similar animals.

Humans make many uses of arthropods, including as food, in art, in stories, and in mythology and religion. Many of these aspects concern insects, which are important both economically and symbolically, from the work of honeybees to the scarabs of Ancient Egypt. Other arthropods with cultural significance include crustaceans such as crabs, lobsters, and crayfish, which are popular subjects in art, especially still lifes, and arachnids such as spiders and scorpions, whose venom has medical applications. The crab and the scorpion are astrological signs of the zodiac.

The subcutaneous tissue (from Latin subcutaneous 'beneath the skin'), also called the hypodermis, hypoderm (from Greek 'beneath the skin'), subcutis, or superficial fascia, is the lowermost layer of the integumentary system in vertebrates. The types of cells found in the layer are fibroblasts, adipose cells, and macrophages. The subcutaneous tissue is derived from the mesoderm, but unlike the dermis, it is not derived from the mesoderm's dermatome region. It consists primarily of loose connective tissue and contains larger blood vessels and nerves than those found in the dermis. It is a major site of fat storage in the body.

In arthropods, a hypodermis can refer to an epidermal layer of cells that secretes the chitinous cuticle. The term also refers to a layer of cells lying immediately below the epidermis of plants.