Most ecological pyramid → pyramid-shape but there are exceptions:
Pyramid of Numbers May be upside down / inverted if:
- Organisms of one trophic level → are parasitic on organisms of another trophic level
- Many small organisms → of 1 trophic level → feed on a large organism of another trophic level
Consider Food Chain:
graph LR Tree --> Bird Bird --> Flea
Pyramid of numbers is inverted.
- Bottom of pyramid is represented by only 1 tree.
- Many birds feed on tree
- Many fleas are parasitic on birds.
Pyramid of Biomass remains broad at bottom and narrow towards top
- One tree has comparatively higher biomass to support the other populations
