Marine nematodes are tiny, unsegmented worms found in various ocean environments, from deep-sea sediments to coastal waters. They play a crucial role in the marine ecosystem by breaking down organic matter and recycling nutrients, which supports the food web. These organisms can vary in size, typically ranging from 0.5 to 5 millimeters in length. Marine nematodes are known for their adaptability, thriving in extreme conditions such as high pressure and low oxygen levels. Their diverse habitats include coral reefs, mangroves, and seagrass beds, making them essential for maintaining the health of marine ecosystems.