Biology:Direct development

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Short description: Growth to adulthood without metamorphosis

Direct development is a concept in biology. It refers to forms of growth to adulthood that do not involve metamorphosis. An animal undergoes direct development if the immature organism resembles a small adult rather than having a distinct larval form.[1] A frog that hatches out of its egg as a small frog undergoes direct development. A frog that hatches out of its egg as a tadpole does not.

Direct development is the opposite of complete metamorphosis. An animal undergoes complete metamorphosis if it becomes a non-moving thing, for example a pupa in a cocoon, between its larval and adult stages.[2]

Examples

  • Most frogs in the genus Callulina hatch out of their eggs as froglets.
  • Springtails and mayflies, called ametabolous insects, undergo direct development.[3]

References

  1. Fang Yan; Xiaolong Liu; Yinpeng Zhang; Zhiyong Yuan (May 28, 2021). "Direct development of the bush frog Raorchestes longchuanensis (Yang and Li 1978) under laborary conditions in Southern China". Journal of Natural History 55 (1–2): 123–132. doi:10.1080/00222933.2021.1895349. https://www.tandfonline.com/doi/abs/10.1080/00222933.2021.1895349. Retrieved March 7, 2023. 
  2. Jens Rolff; Paul R. Johnston; Stuart Reynolds (August 26, 2019). "Complete metamorphosis of insects". Philos Trans R Soc Lond B Biol Sci 374 (1783). doi:10.1098/rstb.2019.0063. PMID 31438816. 
  3. Scott F. Gilbert (2000). "Metamorphosis: The Hormonal Reactivation of Development". Developmental Biology (6 ed.). Sunderland, MA: Sinauer Associates. https://www.ncbi.nlm.nih.gov/books/NBK9986/. Retrieved March 19, 2023.