Editing Exoskeleton (section)

== Growth ==
{{main|Ecdysis}}
Since exoskeletons are rigid, they present some limits to growth. Organisms with open shells can grow by adding new material to the aperture of their shell, as is the case in [[gastropod]]s, [[bivalve]]s, and other [[mollusca]]ns. A true exoskeleton, like that found in panarthropods, must be shed via [[moulting]] ([[ecdysis]]) when the animal starts to outgrow it.<ref name=Ewer>{{Cite journal |journal=PLOS Biology |volume=3 |issue=10 |pages=e349 |title=How the Ecdysozoan Changed Its Coat |date=2005-10-11 |author=John Ewer |doi=10.1371/journal.pbio.0030349 |pmid=16207077 |pmc=1250302 |doi-access=free }}</ref> A new exoskeleton is produced beneath the old one, and the new skeleton is soft and pliable before shedding the old one. The animal will typically stay in a den or burrow during moulting,{{citation needed|date=September 2020}} as it is quite vulnerable to trauma during this period. Once at least partially set, the organism will plump itself up to try to expand the exoskeleton.{{ambiguous|date=September 2020}} The new exoskeleton is still capable of growing to some degree before it is eventually hardened. {{citation needed|date=September 2020}} In contrast, moulting reptiles shed only the outer layer of skin and often exhibit indeterminate growth.<ref>{{cite journal | pmc=4743077 | year=2016 | last1=Hariharan | first1=I. K. | last2=Wake | first2=D. B. | last3=Wake | first3=M. H. | title=Indeterminate Growth: Could It Represent the Ancestral Condition? | journal=Cold Spring Harbor Perspectives in Biology | volume=8 | issue=2 | pages=a019174 | doi=10.1101/cshperspect.a019174 | pmid=26216720 }}</ref> These animals produce new skin and integuments throughout their life, replacing them according to growth. Arthropod growth, however, is limited by the space within its current exoskeleton. Failure to shed the exoskeleton once outgrown can result in the animal's death or prevent subadults from reaching maturity, thus preventing them from reproducing. This is the mechanism behind some insect pesticides, such as [[Azadirachtin]].<ref>{{cite journal | title = Synthesis of Azadirachtin: A Long but Successful Journey |author1=Gemma E. Veitch |author2=Edith Beckmann |author3=Brenda J. Burke |author4=Alistair Boyer |author5=Sarah L. Maslen |author6=Steven V. Ley | doi = 10.1002/anie.200703027 | year = 2007 | journal = Angewandte Chemie International Edition | volume = 46 | pages = 7629–32 | pmid = 17665403 | issue = 40}}</ref>