Cremaster, Nature’s Velcro

 


Chrysalis (cocoon) in insect’s life is a stage of changes where all precautions are taken. The most important of them all, is to stay at one place fixed and safe.

The structure by which Chrysalis is attached to a surface is called Cremaster. It is modified larval anal claspers found at the hind end of Chrysalis.

When the caterpillar (larva) is fully grown, it selects a resting spot (usually, the undersurface of a twig) and spins a silk pad, the size of a small button. It attaches itself to the silk pad, by its last pair of false legs (or the anal feet or anal claspers) and hangs head down.

Rapid convulsions occur along the caterpillar’s body. The skin begins to peel off, revealing the Chrysalis underneath.

The attachment structure between Chrysalis and silk pad now, is the remnant of anal claspers which has become thin and slender. If at this stage, the larval skin peels off completely, there is every danger of Chrysalis losing its grip. Being a delicate bag of fluid, it will crash to death.

But, Chrysalis has the Cremaster, which is thrust from its hind end into the silk pad. The Cremaster is twisted several times and screwed firmly. This provides a secure attachment. The process takes place very fast. Now the larval skin gets totally separated from the Chrysalis and discarded.

Skin shedding is an important step during the initial stages of Chrysalis formation. If the process is left incomplete, the development also will be incomplete. The Cremaster prevents such a mishap.

The Cremaster is ingenious in its construction. It is formed from the anal feet at the right time during skin shedding. It consists of a bulb with hundreds of microscopic hooks or barbs. When this bulb is thrust into the silk pad, the hooks get locked up with the silk threads. In other words it functions like a Velcro. Cremaster is nature’s Velcro. It fastens Chrysalis with silk pad underneath the twig.

In our lives, Velcro is a hook and loop fastener, used in all items from head to toe (Cap to shoe)!!
     
    Read Next Article : Frog Cocoon  

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