1. The pyramid of number in a tree ecosystem is inverted. The primary producer tree is a single unit. The consumers like insects, small birds & large birds are the primary consumers secondary consumers &territory consumers respectively.
Thus the no. of consumer in tree ecosystem is more than that of the producer. The pyramid of biomass in sea is inverted because the biomass of shes (Consumers) exceeds that of phytoplankton (producer).
2. Food chain starts with detritus called as detritus food chain.