What is so different between chordates and other organisms that developed before them?

The animal has a cord or backbone in their body structure are chordates. Contrary, Non-chordates are the animals without backbone or notochord, this the vital difference between chordates and non-chordates is that the. These animals belong to the different phyla of the animal kingdom.

Explanation:

the menstrual cycle – higher tier. negative feedback mechanisms affect the production of hormones in the menstrual cycle. oestrogen also stimulates the release of lh (luteinising hormone) from the pituitary gland, which in turn controls the production of progesterone.