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Holdfast Tubercles Hold A Monarch Chrysalis While It Is Pupating Click on any photo to view a larger image. |
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A J’ing caterpillar wriggles out of its outer ‘skin’ (cuticle) to become a chrysalis. After the skin works up to the top of the J, where it is holding on to its silk button, it reaches out with its cremaster to lock the cremaster’s hooks into the mass of silken loops. Once the cremaster has touched the silken pad, it is attached and does the ‘twist’. The skin (which is bunched up like a dirty sock thrown on the floor by a tired workman) breaks loose and falls away. While the cremaster is reaching out, around, and up to the silk pad, the soft new pupa is suspended in midair. The source of contact is called ‘holdfast tubercles’. These tubercles are protrusions that have small hairs that help hold the skin. In addition to the tubercles, a clear safety band is also used in this process. Because this miracle takes place under the bunched-up skin, it is rarely seen by the human eye. As several Monarchs pupated, we gently pulled back the skin to take photos of these tubercles. (These Monarchs pupated successfully and emerged as healthy Monarch butterflies.) |
Information about holdfast tubercles and the safety band is located here. |