![]() The egg provides the genetic information necessary for all growth and function, including the blueprints for imaginal discs. Complete Metamorphosis Egg Stage of Complete Metamorphosis However, the presence, quantity and balance of 20-hydroxyecdysone (20E) and juvenile hormone (JH) are probably the most important chemical guides of the process of complete metamorphosis. ![]() Various theories exist as to the triggers for the passing from one stage into the next, including starvation, critical weight, gene upregulation, temperature, hormonal stimulation and time. Even the environment in which each form exists can differ. The Four Stages of Complete MetamorphosisĬomplete metamorphosis gives insects greater advantages in terms of survival, with each stage characterized by its behavioral, anatomical and physiological changes. In relation to non-hypermetamorphic insects, the earliest versions of parasitic instars are very mobile and very small, making it much easier for them to find hosts. These additional changes within the normal complete metamorphosis process are found in hypermetamorphic insects of the Strepsiptera orders, as well as in various parasitic wasp, beetle, fly, and mantis-fly species. On the other end of the scale, some insects have very distinct-looking instar forms in the larval stage. However, neotenic insects all go through the four stages of complete metamorphosis. Examples are the female trilobite beetle or bagworm moth. This phenomenon is called neoteny or juvenilization. The production of wings is an expensive process in terms of energy, and the production of a female adult which much resembles the larval form and without wings does, on occasion, occur. The first of these are neotenic insects, the second, hypermetamorphic insects. There are some partial exceptions to the rule of complete metamorphosis. Those species that do not undergo complete metamorphosis and present as nymphs (using the processes involved in incomplete metamorphosis) have their own orders. Other orders that feature holometaboly are Diptera (flies), Neuroptera (including lacewings, alderflies and mayflies), Siphonaptera (fleas), and Hymenoptera (ants, bees and wasps). The best-known holometabolous insects are those included in the orders Lepidoptera (butterflies and moths) and Coleoptera (beetles). The majority of holometabolous insects have wings, although there are groups which feature wingless adults. ![]() Hemimetabolous Complete Metamorphosis ExamplesĬomplete metamorphosis examples cover a wide range of insect orders. Note the very different forms of egg, larva, pupa, and adult (or imago) in holometaboly, and the similar nymph forms of hemimetaboly. The image below shows the different stages of complete metamorphosis in relation to incomplete metamorphosis. Incomplete metamorphosis or hemimetabolous development, on the other hand, has only one stage that is anatomically and physiologically different – the egg form. Each stage is therefore succinctly different from the stage that precedes or follows it. The process requires so much energy, it is simply not possible to go through a complete morphological and anatomical change in one sitting. This transformation requires significant energy, and is split into a sequence of changes at different stages of the insect lifecycle. In complete metamorphosis there are huge differences between larval and adult forms. The more generic term of metamorphosis covers two different processes, one of them being complete metamorphosis, holometabolous development or holometaboly, which is almost completely specific to winged insects. Complete Metamorphosis ExplainedĬomplete metamorphosis must involve four stages. This set of four stages – egg, larva, pupa, and adult – makes up the process of complete metamorphosis. This occurs in the animal world, more specifically the insect world. Complete metamorphosis refers to change in anatomical and physiological form through a series of life stages.
0 Comments
Leave a Reply. |
Details
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |