**4. Spontaneous changes in height**

*Ecosystem and Biodiversity of Amazonia*

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**Figure 9.**

**Figure 8.**

*Sealing of interstices by injection of soaked clay (cl).*

*Reconstruction of the turret after failover.*

A spontaneous increase in turret height to a value held constant thereafter has occasionally been observed, reflecting an increase in the minimum required height discussed above.

A spontaneous decrease in the height of the turret can also be observed, resulting from building a summit inside the turret, below the existing one, which, probably because it is no longer in contact with the moisture inside the burrow, dries up and crumbles (**Figure 10**), revealing the new top. After a few days, the parts above the new summit have completely disappeared and the result is a turret with reduced height.

#### **Figure 10.**

*Spontaneous reduction in the height of the turret by construction of an internal top and drying out of the old one. The white line represents the old wall of the upper part of the turret.*

The reasons leading to the performance of this operation by the nymph remain to be elucidated because, during experiments of artificial lengthening of a turret by transplanting fragments from another one, a nymph does not manifest a requirement of a maximum height; in the long run, it accommodates a higher turret than the one it has built itself; it does not practice the technique which has just been described, nor any other. On the other hand, it ensures the sealing of the modified turret by plugging with soaked clay the interstices between the base of its turret and the implants received, in the same way as described above (**Figure 8**).
