Ecological pyramids are of 3 types (a) Pyramid of Energy: Always upright, without any exception, because at successive trophic levels only 10% energy is transferred. (b) Pyramid of number: Mostly upright, except - tree ecosystem, in which on the single large tree several birds survive and on these birds several parasites are present. (c) Pyramid of Biomass: Mostly upright, except - Sea/aquatic ecosystem, in which producers are planktons which have very less weight although dependent smaller and larger fishes have comparatively more weight.