Question

What type of interaction is shown by algae growing on the shell of a turtle without harming it?
A) Predation
B) Commensalism
C) Interspecific competition
D) Mutualism
E) Parasitism

Answer 1

The study of different organisms, their interaction and communication with each other and their surrounding environment is called ecology. The interaction among different species of organisms living in a community is called population interaction.

Complete answer:
To answer this question we will look at each option individually.
A) Predation- In this type of population interaction, one species (called predator) fully depends on another species (called prey) for its survival. In predation, the prey species is affected negatively while the predator species is affected positively. Eg. Sparrow (predator) feeding on seeds (prey)

B) Commensalism- In commensalism, one of the interacting species is benefitted while the other is neither harmed nor benefitted. Eg. Orchid growing as an epiphyte on the mango branch.

C) Interspecific competition- Interspecific competition occurs between the organisms of different species due to various reasons like limited resources. Both the species are affected negatively due to such interaction.

D) Mutualism- In mutualism both the interacting species are benefitted without harming each other. The interacting species depend on each other for food and survival. Eg. Lichens is the mutualist association of fungi and algae.

E) Parasitism- In parasitism one species (parasite) feed off of another species (host). In such interaction the parasite benefits while the host is affected negatively. Eg. Cuscuta growing on hedge plants.
An alga growing on the shell of a turtle without harming it is an example of commensalism as algae are deriving benefit by living on the shell of a turtle while the turtle is neither benefitted nor harmed.

Therefore, the correct answer is option ‘B’.

Note: Gause’s ‘Competitive Exclusion Principle’
- It states that two closely related species competing for the same resources cannot co-exist indefinitely and the inferior one will be eventually eliminated as the resources are limited.
- Recent studies state that species facing such competition evolve mechanisms that promote co-existence rather than exclusion.