Exclusive extract: metamorphosis

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It’s morphing time


Discover the transformative power of metamorphosis and the range of species that undergo it


As children we are taught the simple transformations of some species; the iconic blossoming of a butterfly and the tail-shedding cycle of tadpoles, for example. Known as metamorphosis, this process completely changes an animal’s anatomy. However, this transformation is far from simple and spreads across a wide range of species.

At first glance, it’s easy to come to the conclusion that a caterpillar and butterfly could be identified as two completely different species. English physician William Harvey did just that in 1651, describing metamorphosis as a process whereby free-living embryos had escaped eggs, which provided little nutritional value. He also suggested that what we now know is the pupa stage was in fact a second egg from which a new species was reborn. Dutch biologist Jan Swammerdam later discredited Harvey’s theory in 1669 when he realised that the larva, pupa and adult stages all belonged to a single species.

There are two different types of metamorphosis: complete and incomplete. The differences between the two isn’t whether or not a tadpole becomes a complete frog versus one that still has its tail; it relates to the species’ level of anatomical change. Complete metamorphosis occurs in those that completely change their physical characteristics, for example, a caterpillar changing into a butterfly. On the other hand, incomplete metamorphosis results in only some changes, such as those seen in crickets, where the larval stage doesn’t involve the development of wings but otherwise does look similar to its adult counterpart.


You can read the rest of the feature in our latest issue


Extract from Metamorphosis by Scott Dutfield. Featured in How It Works 110.

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