Metamorphosis
![](http://upload.wikimedia.org/wikipedia/commons/thumb/6/66/Dragonfly_metamorphosis.jpg/220px-Dragonfly_metamorphosis.jpg)
Metamorphosis is a
Generally organisms with a larval stage undergo metamorphosis, and during metamorphosis the organism loses larval characteristics. [4]
Etymology
The word metamorphosis derives from
Hormonal control
In insects, growth and metamorphosis are controlled by
In chordates, metamorphosis is iodothyronine-induced and an ancestral feature of all chordates.[11]
Insects
![](http://upload.wikimedia.org/wikipedia/commons/thumb/f/f3/Locust_instars_NMNS.jpg/220px-Locust_instars_NMNS.jpg)
All three categories of metamorphosis can be found in the diversity of insects, including no metamorphosis ("ametaboly"), incomplete or partial metamorphosis ("hemimetaboly"), and complete metamorphosis ("holometaboly"). While ametabolous insects show very little difference between larval and adult forms (also known as "
Development and terminology
![](http://upload.wikimedia.org/wikipedia/commons/thumb/a/a0/Holometabolous_vs._Hemimetabolous.svg/220px-Holometabolous_vs._Hemimetabolous.svg.png)
In
In
Evolution
The earliest insect forms showed direct development (
A number of hypotheses have been proposed to explain the evolution of holometaboly from hemimetaboly, mostly centering on whether or not the intermediate stages of hemimetabolous forms are homologous in origin to the pupal stage of holometabolous forms.
Temperature-dependent metamorphosis
According to a 2009 study, temperature plays an important role in insect development as individual species are found to have specific thermal windows that allow them to progress through their developmental stages. These windows are not significantly affected by ecological traits, rather, the windows are phylogenetically adapted to the ecological circumstances insects are living in.[15]
Recent research
According to research from 2008, adult Manduca sexta is able to retain behavior learned as a caterpillar.[16] Another caterpillar, the ornate moth caterpillar, is able to carry toxins that it acquires from its diet through metamorphosis and into adulthood, where the toxins still serve for protection against predators.[17]
Many observations published in 2002, and supported in 2013 indicate that
Below is the sequence of steps in the metamorphosis of the butterfly (illustrated):
![](http://upload.wikimedia.org/wikipedia/commons/thumb/2/29/Metamorphosis_of_butterfly_%28PSF%29.png/220px-Metamorphosis_of_butterfly_%28PSF%29.png)
1 – The larva of a butterfly
2 – The pupa is now spewing the thread to form chrysalis
3 – The chrysalis is fully formed
4 – Adult butterfly coming out of the chrysalis
- Sequence illustrating complete metamorphosis in the cabbage white butterfly, Pieris rapae
-
pupa ready to hatch
Chordata
Amphioxus
In
Fish
Some fish, both bony fish (Osteichthyes) and jawless fish (Agnatha), undergo metamorphosis. Fish metamorphosis is typically under strong control by the thyroid hormone.[21]
Examples among the non-bony fish include the lamprey. Among the bony fish, mechanisms are varied.
The
Many species of
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. In the pre-adult freshwater stage, the eel also has phenotypic plasticity because fish-eating eels develop very wide mandibles, making the head look blunt. Leptocephali are common, occurring in all Elopomorpha (tarpon- and eel-like fish).
Most other bony fish undergo metamorphosis initially from
Amphibians
![](http://upload.wikimedia.org/wikipedia/commons/thumb/0/0e/RanaTemporariaLarva2.jpg/220px-RanaTemporariaLarva2.jpg)
![](http://upload.wikimedia.org/wikipedia/commons/thumb/5/5a/Rana_Temporaria_-_Larva_Final_Stage.jpg/220px-Rana_Temporaria_-_Larva_Final_Stage.jpg)
In typical amphibian development, eggs are laid in water and larvae are adapted to an aquatic lifestyle.
Metamorphosis in amphibians is regulated by
Frogs and toads
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. Front legs are formed under the gill sac, and hindlegs are visible a few days later. Following that there is usually a longer stage during which the tadpole lives off a vegetarian diet. Tadpoles use a relatively long, spiral‐shaped gut to digest that diet. Recent studies suggest tadpoles do not have a balanced homeostatic feedback control system until the beginning stages of metamorphosis. At this point, their long gut shortens and begins favoring the diet of insects.[24]
Rapid changes in the body can then be observed as the lifestyle of the frog changes completely. The spiral‐shaped mouth with horny tooth ridges is resorbed together with the spiral gut. The animal develops a big jaw, and its gills disappear along with its gill sac. Eyes and legs grow quickly, a tongue is formed, and all this is accompanied by associated changes in the neural networks (development of stereoscopic vision, loss of the lateral line system, etc.) All this can happen in about a day, so it is truly a metamorphosis. It is not until a few days later that the tail is reabsorbed, due to the higher thyroxin concentrations required for tail resorption.
Salamanders
Salamander development is highly diverse; some species go through a dramatic reorganization when transitioning from aquatic larvae to terrestrial adults, while others, such as the
Newts
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. Newts' gills are never covered by a gill sac and will be resorbed only just before the animal leaves the water. Adults can move faster on land than in water.
Caecilians
Basal caecilians such as
See also
- Developmental biology – Study of how organisms develop and grow
- Direct development – Growth to adulthood without metamorphosis
- Gosner stage – System of describing stages of development in anurans
- Hypermetamorphosis – High variability forms of complete metamorphosis
- Morphogenesis – Biological process that causes an organism to develop its shape
References
- ^ "metamorphosis | biology | Britannica". www.britannica.com. Retrieved 2022-04-01.
- ^ "What animals undergo incomplete metamorphosis? – Easierwithpractice.com". easierwithpractice.com. Retrieved 2022-04-01.
- S2CID 208541817.
- PMID 11145872. Retrieved 7 March 2022.
- ^ Liddell, Henry George; Scott, Robert (1940). "Metamorphosis". A Greek-English Lexicon. Oxford: Clarendon Press. Retrieved 2012-08-26 – via perseus.tufts.edu.
- ^ "Online Etymology Dictionary". Etymonline.com. Retrieved 2012-08-26.
- ^ Davies, 1998. Chapter 3.
- ^ Gullan, P.J. & Cranston, P.S. 6.3 Process and Control of Moulting in The Insects: An Outline of Entomology. Blackwell Publishing, 2005. pp. 153-156.
- PMID 5217430.
- PMID 22174880.
- ^ S2CID 18587560.
- .
- PMID 23676900.
- ^ Gullan, P.J. & Cranston, P.S. 6.2 Life History Patterns and Phases in The Insects: An Outline of Entomology. pp. 143–153. 2005 by Blackwell Publishing
- ^ Dixon, A. F. G., A. Honěk, P. Keil, M. A. A. Kotela, A. L. Šizling, and V. Jarošík. 2009. Relationship between the minimum and maximum temperature thresholds for development in insects. Funct. Ecol. 23: 257–264.
- PMID 18320055.
- ^ Conner, W.E. (2009). Tiger Moths and Woolly Bears—behaviour, ecology, and evolution of the Arctiidae. New York: Oxford University Press. pp. 1–10.
- PMID 23519152.
- PMID 12072175.
- PMID 31438816.
- ^ PMID 21959163.
- ^ Mader, Sylvia, Biology 9th ed. Ch. 31
- ^ Peter B. Moyle and Joseph J. Cech Jr, Fishes: an introduction to ichthyology 5th ed. 9.3: "Development" pp 148ff
- S2CID 4853293.
- S2CID 34285867. Retrieved 28 December 2020.
- PMID 10629095.
- PMID 15336675.
Bibliography
- Davies, R.G. (1998). Outlines of Entomology. Chapman and Hall. Second Edition. Chapter 3.
- Williamson D.I. (2003). The Origins of Larvae. Kluwer.
External links
![](http://upload.wikimedia.org/wikipedia/en/thumb/4/4a/Commons-logo.svg/12px-Commons-logo.svg.png)
The dictionary definition of metamorphosis at Wiktionary