Poisonous species are organisms that produce toxic substances that can harm or kill other organisms when ingested or touched. These toxins can serve as a defense mechanism against predators or can be used to capture prey. Examples of poisonous species include certain types of frogs, snakes, and plants. Some well-known poisonous species include the blue poison dart frog, which contains potent toxins in its skin, and the pufferfish, which can be deadly if consumed improperly. Understanding these species is important for both ecological balance and human safety, as interactions with them can have serious consequences.