More than 10 species of invertebrates became extinct within a year from the American pacific coast when Pisaster starfish was removed. This extinction was due to -

Answer

To solve the question regarding the extinction of invertebrate species after the removal of Pisaster starfish from the American Pacific coast, we can follow these steps:

### Step 1: Understand the Role of Pisaster Starfish
Pisaster starfish is a keystone species in its ecosystem. This means that it has a disproportionately large effect on its environment relative to its abundance.

**Hint:** Consider what a keystone species is and how it affects the biodiversity of its habitat.

### Step 2: Identify the Prey of Pisaster Starfish
Pisaster primarily feeds on certain invertebrates, particularly mussels. By preying on these species, Pisaster helps to control their population.

**Hint:** Think about the relationship between predator and prey in an ecosystem.

### Step 3: Analyze the Impact of Removing Pisaster
When Pisaster was removed, the population of its prey, such as mussels, likely increased significantly due to the absence of predation. This can lead to overpopulation of these species.

**Hint:** Reflect on what happens to an ecosystem when a predator is removed.

### Step 4: Consider the Consequences of Overpopulation
The overpopulation of mussels and other prey species can lead to competition for resources, such as space and food. This competition can negatively impact other invertebrate species, leading to their decline or extinction.

**Hint:** Think about how competition affects species diversity in an ecosystem.

### Step 5: Conclude the Reason for Extinction
The extinction of more than 10 species of invertebrates can be attributed to the removal of Pisaster starfish, which disrupted the balance of the ecosystem. The lack of predation led to overpopulation of certain species, resulting in competition and ultimately the extinction of other invertebrate species.

**Hint:** Summarize the chain reaction that occurred due to the removal of the keystone species.

### Final Answer
The extinction of more than 10 species of invertebrates from the American Pacific coast after the removal of Pisaster starfish was due to the disruption of the ecosystem balance, leading to overpopulation of certain prey species and subsequent competition for resources among invertebrates.