|
The Phasmatodea (also known as Phasmida or Phasmatoptera) are an order of insects, whose members are variously known as stick insects (in Europe and Australasia), stick-bugs or walking sticks (in the United States and Canada), phasmids, ghost insects and leaf insects (generally the family Phylliidae). The group's name is derived from the Ancient Greek φάσμα ''phasma'', meaning an apparition or phantom, referring to the resemblance of many species to sticks or leaves. Their natural camouflage makes them difficult for predators to detect, but many species have a secondary line of defence in the form of startle displays, spines or toxic secretions. The genus ''Phobaeticus'' includes the world's longest insects. Members of the order are found all over the world except for the Antarctic and Patagonia, but they are most abundant in the tropics and subtropics. They are herbivorous with many species living unobtrusively in the tree canopy. They have a hemimetabolous life cycle with three stages: eggs, nymphs and adults. Many phasmids are parthenogenic, and do not required fertilised eggs for female offspring to be produced. In hotter climates, they may breed all year round; in more temperate regions, the females lay eggs in the autumn before dying, and the new generation hatches out in the spring. Some species have wings and can disperse by flying, while others are more restricted. ==Description== Phasmids can be relatively large, ranging from to over in length. Females of the genus ''Phobaeticus'' are the world's longest insects, measuring up to in total length in the case of ''Phobaeticus chani'', including the outstretched legs. The heaviest species of phasmid is likely to be ''Heteropteryx dilatata'', the females of which may weigh as much as .〔(【引用サイトリンク】url=http://phasmid-study-group.org/content/Phasmids-Introduction-Stick-Insects-and-Leaf-Insects )〕 Some phasmids have cylindrical stick-like bodies, while others have flattened, leaflike shapes. Many species are wingless, or have reduced wings. The thorax is long in the winged species, since it houses the flight muscles, and is typically much shorter in the wingless forms. Where present, the first pair of wings is narrow and cornified (hardened), while the hind wings are broad, with straight veins along their length and multiple cross-veins. The body is often further modified to resemble vegetation, with ridges resembling leaf veins, bark-like tubercles, and other forms of camouflage. A few species, such as ''Carausius morosus'', are even able to change their pigmentation to match their surroundings. The mouthparts project out from the head. Chewing mandibles are uniform across species. The legs are typically long and slender, and some species are capable of limb autotomy (shedding).〔 Phasmids have long, slender antennae, as long as or longer than the rest of the body in some species. All phasmids possess compound eyes, but ocelli (light-sensitive organs) are only found in some winged males.〔 Phasmids have an impressive visual system that allow them to perceive significant detail even in dim conditions, which suits their typically nocturnal lifestyle. They are born equipped with tiny compound eyes with a limited number of facets. As phasmids grow through successive molts, the number of facets in each eye is increased along with the number of photoreceptor cells. The sensitivity of the adult eye is at least tenfold that of the nymph in its first instar (developmental stage). As the eye grows more complex, the mechanisms to adapt to dark/light changes is also enhanced: eyes in dark conditions evidence less screening pigments, which would block light, than during the daytime, and changes in the width of the retinal layer to adapt to changes in available light are significantly more pronounced in adults. However, the larger size of the adult insects' eyes makes them more prone to radiation damage. This explains why fully grown individuals are mostly nocturnal. Lessened sensitivity to light in the newly emerged insects helps them to escape from the leaf litter wherein they are hatched and move upward into the more brightly illuminated foliage. Young stick insects are diurnal (daytime) feeders and move around freely, expanding their foraging range. Stick insects have two types of pad on their legs: sticky "toe pads" and non-stick "heel pads" a little further up their legs. The heel pads are covered in microscopic hairs which create strong friction at low pressure, enabling them to grip without having to be peeled energetically from the surface at each step. The sticky toe pads are used to provide additional grip when climbing but are not used on a level surface. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Phasmatodea」の詳細全文を読む スポンサード リンク
|