Unlike the giraffe, the length of the limbs is due to the elongation of their upper segments, and that of the neck to the lengthening of only the hinder vertebrae.
This order can be traced with certainty back to the early Jurassic epoch, while the Permian fossil Eugereon, and the living order - specially modified in many respects - of the Thysanoptera indicate steps by which the aberrant suctorial and piercing mouth of the Hemiptera may have been developed from the biting mouth of primitive Isopteroids, by the elongation of some parts and the suppression of others.
The Fata Morgana, frequently seen in the Straits of Messina, consists of an apparent vertical elongation of an object situated on the opposite shore.
With the elongation of the body, the dorsal shield begins to project posteriorly as a shell-fold, which may increase in size to envelop more or less of the body or may disappear altogether.
- Whatever the shape and size of the individual cell, cell-filament or cell-colony, the immediate visible results of active nutrition are elongation of the cell and its division into two equal halves, t;o?.