metamorphosis, in biology, striking change of form or structure in an individual after hatching or birth. It is wingless, and its form and habits are suited for growth and development rather than reproduction. Both of these changes are impressive, but maybe the most amazing animal transformation happens in the insect world. These physical changes as well as those involving growth and differentiation are accompanied by alterations of the organisms physiology, biochemistry, and behaviour. meta- "change" + morphe "form") as a biological process is generally attributed to a subset of animals: most famously insects and amphibians, but some fish and many marine invertebrates as well. 7 Jul 2023. https://askabiologist.asu.edu/explore/metamorphosis. The basic shape, form, and structure of an organism (whether animal, plant, or fungus) emerges as a result of a sequence of developmental adjustments. The size and morphological differences between nymphs in different instars are small, often just differences in body proportions and the number of segments; in later instars, external wing buds form. In typical amphibian development, eggs are laid in water and larvae are adapted to an aquatic lifestyle. "Metamorphosis." By juvenile, I mean a stage with most of the morphological, physiological, and ecological traits of an adult, but typically not reproductive. People change too, but our development is not as impressive as that of insects. The change is dramatic, and the baby stage looks very different from the adult stage. Without reproductively mature members, these species would quickly die off. The dead cells are then cannibalized for energy and raw materials to make other cells. Which of the following organisms undergo incomplete metamorphosis?. In biology, the imago ( Latin for "image") is the last stage an insect attains during its metamorphosis, its process of growth and development; it is also called the imaginal stage, the stage in which the insect attains maturity. Blanks indicate that those features are not considered by the author to be integral to metamorphosis. 2 The pupa is now spewing the thread to form chrysalis Funct. Following that there is usually a longer stage during which the tadpole lives off a vegetarian diet. Why has metamorphosis apparently evolved repeatedly in the history of multicellular life? Depending on the metamorphic taxon, the extended phase can precede, follow, or be coincident with the shorter phase. [26] More recently diverged caecilians (the Teresomata) do not undergo an ontogenetic niche shift of this sort and are in general fossorial throughout their lives. A. After undergoing a partial metamorphosis, it becomes a saltwater fish. While ametabolous insects show very little difference between larval and adult forms (also known as "direct development"), both hemimetabolous and holometabolous insects have significant morphological and behavioral differences between larval and adult forms, the most significant being the inclusion, in holometabolus organisms, of a pupal or resting stage between the larval and adult forms. Among the most dramatic and thoroughly studied examples of metamorphosis are the insects. Metamorphosis is a more or less substantial morphological transformation between 2 multicellular phases in an organism's life cycle, often marking the transition from a pre-reproductive to a reproductive life stage. The European eel has a number of metamorphoses, from the larval stage to the leptocephalus stage, then a quick metamorphosis to glass eel at the edge of the continental shelf (eight days for the Japanese eel), two months at the border of fresh and salt water where the glass eel undergoes a quick metamorphosis into elver, then a long stage of growth followed by a more gradual metamorphosis to the migrating phase. For adaptation to a water phase, prolactin is the required hormone, and for adaptation to the land phase, thyroxin. "Metamorphosis Natures Ultimate Transformer". Among the bony fish, mechanisms are varied. ", Biologydictionary.net Editors. [11], Some fish, both bony fish (Osteichthyes) and jawless fish (Agnatha), undergo metamorphosis. The important thing is that the person using the word defines what he or she means by metamorphosis in the context within which he or she is writing. In holometabolous insects, molts between larval instars have a high level of juvenile hormone, the moult to the pupal stage has a low level of juvenile hormone, and the final, or imaginal, molt has no juvenile hormone present at all. To accomplish this lifestyle change, juvenile flounder essentially flip over on their sides and make one side of their body into their belly. The basic rules of pattern formation seem to be that regional specification (directed by organisms producing morphogens) occurs first, regulating gene activity in ways specifically geared to metamorphosis so that particular cells are first specified (a state which is still flexible) and then determined (a state which is inflexible) to their differentiated fates. Metamorphosis is a life-history transition that involves radical changes in habitat, morphology, and physiology. The process is triggered by an external (environmental) and/or internal (hormonal) cue. Fish, such as salmon, must transform so they can move from fresh water to salt water and back to freshwater. Basal caecilians such as Ichthyophis go through a metamorphosis in which aquatic larva transition into fossorial adults, which involves a loss of the lateral line. B. Frogs and insects must have evolved from a common ancestor that underwent metamorphosis. Metamorphosis is tightly regulated within an animal's life cycle by hormones and a variety of environmental signals. For example, in recent years, the physiological mechanisms that control life-history transition among incredibly disparate organisms such as fungi, slime molds, plants, and animals share some similarities. The metamorphosis of a tadpole into a frog is a little less violent than that of a caterpillar into a butterfly, but the processes share some important common features. Both complete and incomplete metamorphosis extend from the egg stage to the adult stage. I do not consider parr-smolt transformation in salmonids as a metamorphosis. Genes, morphology, performance, and fitness: quantifying organismal performance to understand adaptive evolution, Daily Torpor in Birds and Mammals: Past, Present, and Future of the Field, Non-torpid Heterothermy in Mammals: Another Category Along The Homeothermy-hibernation Continuum, Loss of collagen gene expression in the notochord of the tailless tunicate Molgula occulta, Hydrodynamic Diversity of Jets Mediated by Giant And Non-Giant Axon Systems in Brief Squid, About Integrative and Comparative Biology, About the Society for Integrative and Comparative Biology, Receive exclusive offers and updates from Oxford Academic, Copyright 2023 The Society for Integrative and Comparative Biology. & Cranston, P.S. According to Duellman and Trueb (1986) Metamorphosis can be defined as "a radical transformation from larval life to the adult stage involving structural, physiological, biochemical and behavioural changes" . Examples that do not fit my definition: most fish except those, like flounders, that undergo a change in habitat and radical changes in morphology, and those, like salmon, that change habitat and physiology; flowering in plants; the transition to the adult in the roundworm C. elegans; the formation of the juvenile in the direct-developing slime star Pteraster tesselatus. Examples of organisms that fit this definition include larvae of many marine invertebrates (for example, cnidarians, molluscs, polyclad flatworms, nemerteans, polychaete annelids, sipunculids, echiurids, echinoderms, ascidians, hemichordates, phoronids, bryozoans) as well as freshwater and terrestrial larvae of holometabolous insects, and those vertebrates that have a distinct larval stage (like tadpoles of indirect-developing frogs). Metamorphosis is a rapid and sudden change in physiology and morphology that an organism undergoes to transform from a juvenile into an adult. Development proceeds in repeated stages of growth and ecdysis (moulting); these stages are called instars. meta- "change" + morphe "form") as a biological process is generally attributed to a subset of animals: most famously insects and amphibians, but some fish and many marine invertebrates as well. ", "Essential role of grim-led programmed cell death for the establishment of corazonin-producing peptidergic nervous system during embryogenesis and metamorphosis in Drosophila melanogaster", "The Origins and Evolution of Vertebrate Metamorphosis", "To eat or not to eat: ontogeny of hypothalamic feeding controls and a role for leptin in modulating life-history transition in amphibian tadpoles", "Consequences of Metamorphosis for the Locomotor Performance and Thermal Physiology of the Newt Triturus cristatus", 10.1002/(sici)1097-4687(200001)243:1<3::aid-jmor2>3.3.co;2-4, https://en.wikipedia.org/w/index.php?title=Metamorphosis&oldid=1157210875. The changes are rapid and the results are acute. We present this article not only as an introduction to this symposium volume, but also as a reference tool that can be used by others interested in metamorphosis. While every effort has been made to follow citation style rules, there may be some discrepancies. Newts' gills are never covered by a gill sac and will be resorbed only just before the animal leaves the water. Bees, beetles, ants, and flies all use this strategy. (2017, July 04). The animal develops a big jaw, and its gills disappear along with its gill sac. Competence, the developmental capacity to undergo metamorphosis, can last from days to months in marine invertebrate larvae. It furthers the University's objective of excellence in research, scholarship, and education by publishing worldwide, This PDF is available to Subscribers Only. This set of four stages - egg, larva, pupa, and adult - makes up the process of complete metamorphosis. meta- "change" + morphe "form") as a biological process is generally attributed to a subset of animals: most famously insects and amphibians, but some fish and many marine invertebrates as well. Fish, such as salmon, must transform so they can move from fresh water to salt water and back to freshwater. 5Kohtaro Tanaka notes that plant flowering should be considered metamorphic (or metamorphic-like), even though it does not involve habitat shifts, and morphological changes occur only in parts of individual plants. In newts, metamorphosis occurs due to the change in habitat, not a change in diet, because newt larvae already feed as predators and continue doing so as adults. As a neuroscientist, I am especially keen to find out new ways in which activity in neurons can regulate developmentnot just of themselves, or of other neurons (a well-trodden area of inquiry), but of the entire animal. If adaptive shifts accompanying major morphological change are really what we mean by metamorphosis, then we might drop the requirement for generation of the adult body plan, and include the redia-to-cercaria transition in trematodes (Platyhelminthes). This transformation marks a transition between distinct stages in life history (for example larva and juvenile), which often occupy and are adapted to different environments (for example have different means of locomotion and feeding). If there is a common cross-phyletic toolbox of morphogenetic mechanisms, yet a diversity of sensory cues that initiate metamorphosis, how do the latter plug into the former? These extensions may be especially useful in cases where either the taxa of interest are morphologically simple throughout their life history (for example sponges, cnidarians), or when the biological significance of specific morphological characteristics used to separate stages would be questionable (for example the apical tuft in marine invertebrate larvae). Does this sound like a fantastic and unbelievable story to you? Retrieved July 7, 2023 from https://askabiologist.asu.edu/explore/metamorphosis, Page Baluch. At least some metamorphosing species did not start out that way: the earliest insects basically did hatch as full-grown adults. But in adulthood, flounder are flat fish which camouflage themselves by swimming on their bellies, pressed against the sea bed. Metamorphosis is a process some animals go through to become adults. With frogs and toads, the external gills of the newly hatched tadpole are covered with a gill sac after a few days, and lungs are quickly formed. It follows the final ecdysis of the immature instars. These similarities caused me to wonder whether it is valid to conceive of these life-history transitions as a metamorphosis because of this shared feature. From an echinoderm/amphibian/holometabolous insect view of metamorphosis, I do not know if these would qualify as true metamorphoses, as the parasitic stage may have a morphology similar to an immature adult stage. The word metamorphosis comes from the Greek and means to transform. The most famous example is that of the butterfly, which starts out as a worm-like, leaf-eating caterpillar and transforms into a flying, nectar-drinking creature with an exoskeleton. adj., adj metamorphic. Thus, I define metamorphosis, in the broadest sense, as a transition between vegetative and sexually reproductive multicellular stages of a life history. The ecologist Henry Wilbur [ 1] noted that many organisms have complex life cycles that include 'an abrupt ontogenetic change in an individual's morphology, physiology and behaviour, usually associated with a change in habitat'. Ametabolous insects such as the firebrat, are truly direct developers, with the adult distinguished only by size and genitalia. Starfishes and other echinoderms undergo a metamorphosis that includes a change from the bilateral symmetry of the larva to the radial symmetry of the adult. As a way of addressing the applicability of metamorphosis across kingdoms, each author responded to the following question: Is the vegetative to flower transition in angiosperms an example of metamorphosis? (last column). This article was most recently revised and updated by, https://www.britannica.com/science/metamorphosis, National Center for Biotechnology Information - Metamorphosis: The Hormonal Reactivation of Development, Arizona State University - The College of Liberal Arts and Sciences - Ask A Biologist - All about Metamorphosis, Academia - Analysis: Franz Kafka's The Metamorphosis, metamorphosis - Children's Encyclopedia (Ages 8-11), metamorphosis - Student Encyclopedia (Ages 11 and up). But certain groups of cells survive, turning the soup into eyes, wings, antennae and other adult structures. It includes the shedding and replacement of horns, hair, skin, and feathers. Indeed, the hard shell of the cocoon is required not just to protect the metamorphosing insect from attack: it is required to keep its liquefying body bound together, lest it ooze away! [13], The earliest insect forms showed direct development (ametabolism), and the evolution of metamorphosis in insects is thought to have fuelled their dramatic radiation (1,2). [17], Many observations published in 2002, and supported in 2013 indicate that programmed cell death plays a considerable role during physiological processes of multicellular organisms, particularly during embryogenesis, and metamorphosis. Biologydictionary.net Editors. [2] Animals can be divided into species that undergo complete metamorphosis ("holometaboly"), incomplete metamorphosis ("hemimetaboly"), or no metamorphosis ("ametaboly").[3]. Molting, which is regulated by hormones, occurs throughout the animal kingdom. fatty metamorphosis any normal or pathologic transformation of fat, including fatty infiltration and fatty degeneration. In some animals a hormone cascade follows, with the trigger hormone causing the release of several other hormones that act on different parts of the animals body. Incomplete metamorphosis: a change in body form with three stages: egg, nymph, and adult. By consuming the proteins, vitamins, and minerals everything you need to build a butterfly these imaginal discs are able to grow incredibly quickly, developing into the butterflys mature body parts. [15], According to research from 2008, adult Manduca sexta is able to retain behavior learned as a caterpillar. Because most embryonic development is outside the parental body, development is subject to many adaptations due to specific ecological circumstances. Check out a sample Q&A here See Solution star_border Students who've seen this question also like: Biology (MindTap Course List) Speciation And Macroevolution. Chemical signals may contribute to a metamorphic activity around a structure (cell or organ), which permits continued development of that structure, but inhibits formation of another structure of the same type. The larva differs greatly from the adult. Biologydictionary.net Editors. The word metamorphosis derives from Ancient Greek , "transformation, transforming",[5] from - (meta-), "after" and (morphe), "form". Within the genus Ambystoma, species have evolved to be pedomorphic several times, and pedomorphosis and complete development can both occur in some species.[21]. How Did Insect Metamorphosis Evolve? An academic unit ofThe College of Liberal Arts and Sciences, You may need to edit author's name to meet the style formats, which are in most cases "Last name, First name. Examples range from the classic larval/juvenile transition in benthic invertebrates such as ascidians, to epitoky in some polychaetes. The Author 2006. This radical change allows butterflies to complete their life cycle very efficiently, with no competition between adult butterflies and caterpillars for food. 4 Adult butterfly coming out of the chrysalis, In cephalochordata, metamorphosis is iodothyronine-induced and it could be an ancestral feature of all chordates. Holometabolous insects such as flies and moths have complete metamorphosis, while hemimetabolous insects, such as crickets and grasshoppers merely gain functional wings and genitalia at the final molt. Similar to most entomologists, I consider insects of the monophyletic Holometabola to be truly metamorphic. Oxford University Press is a department of the University of Oxford.
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