Long periods of darkness 65. Permafrost is found here 66. Rainfall amount not temperature is a deciding factor in their classification. This biome contains the most diverse forms of living organisms. This is a grassland with scattered clumps of trees.
Jointed legs are their main characteristic.
They contain nematocysts 71. Segmented worms 72. The anus first appeared in this group of organisms. Developed the first amniote egg. Does not contain a swim bladder.