Why are there few gymnosperms, mammals in nature? Why are there many arthropods, molluscs, protozoa?

Among the most common representatives of gymnosperms are spruce, pine, juniper, fir, etc. Mammals: cat, dog, elephant, man, etc. The life cycle of gymnosperms is longer, so, for example, a pine tree can give seeds only after 10-12 years of life, the life expectancy in general reaches 100 years.

Arthropods: insects, crustaceans, arachnids, millipedes.

Molluscs: chitons, gastropods, bivalves, etc.

Protozoa: ciliates, radiolarians, sunflowers, flagellates, sporozoans, ciliates.

Life expectancy in mammals and gymnosperms exceeds less highly organized life forms of arthropods, protozoa.