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The red lionfish, Pterois volitans, has beautiful red stripes, streaming fins, and a fearless disposition, and it is deadly. Native to the Pacific Ocean, the red lionfish was first discovered on coral reefs in the Bahamas in 1985. The species has spread to over 3 million square kilometers of the western Atlantic and Gulf of Mexico. Lionfish have a voracious appetite for native fish, are armed with venomous spines, and have no natural predators in their new range.
Why are species like the lionfish considered 'invasive'?
a. They are found in areas where they are not native.
b. They were accidentally introduced by humans.
c. They spread aggressively and displace native species.
d. They are predators of other fish.

Verified step by step guidance

1. Begin by understanding the term 'invasive species'. Invasive species are organisms that are not native to a specific location and have a tendency to spread, which can cause damage to the environment, human economy, or health.
2. Consider the characteristics of the lionfish mentioned in the problem. They are native to the Pacific Ocean but have spread to the western Atlantic and Gulf of Mexico, which indicates they are found in areas where they are not native.
3. Evaluate the impact of lionfish on the local ecosystem. They have a voracious appetite for native fish and no natural predators in their new range, which suggests they spread aggressively and displace native species.
4. Reflect on how the lionfish might have been introduced to these new areas. While the problem does not specify, many invasive species are accidentally introduced by human activities, such as through ballast water in ships or the aquarium trade.
5. Analyze the options given in the problem. Consider which characteristics are most commonly associated with invasive species: being non-native, spreading aggressively, and displacing native species. This will help identify the correct reasons why lionfish are considered invasive.

Key Concepts

Invasive Species

Invasive species are organisms that are introduced to a new environment where they are not native. They often spread rapidly and can cause harm to the local ecosystem, economy, or human health. Their success in new areas is typically due to a lack of natural predators and their ability to outcompete native species for resources.

Ecological Impact

The ecological impact of invasive species like the lionfish includes the disruption of local ecosystems. They can outcompete native species for food and habitat, leading to a decline in biodiversity. This can result in altered food webs and ecosystem functions, potentially causing long-term environmental changes.

Human-Mediated Introduction

Human-mediated introduction refers to the unintentional or intentional introduction of species to new environments by human activities. This can occur through various means such as shipping, trade, or the release of pets. Such introductions can lead to the establishment of invasive species, as seen with the lionfish in the Atlantic Ocean.