Grass (Trophic Level 1): The base of the pyramid has a large number of grass plants, supporting many herbivores (rabbits).
Rabbit (Trophic Level 2): The number of rabbits is smaller than grass because they are herbivores, and they rely on the grass for food.
Wild dog (Trophic Level 3): Wild dogs feed on rabbits, so there are fewer wild dogs than rabbits, as fewer carnivores can be supported by the herbivores.
Barnacle and whale shows commensalism.
Flea (Trophic Level 4): Fleas are parasites that live on wild dogs. While there are fewer wild dogs than rabbits, fleas can be highly numerous on each wild dog.