amoebaa: Single-celled protists, these microbes catch food and move about by extending fingerlike projections of a colorless material called protoplasm. Amoebas are either free-living in damp environments or they are parasites.

bacteria: (singular: bacterium) Single-celled organisms. These dwell nearly everywhere on Earth, from the bottom of the sea to inside other living organisms (such as plants and animals). Bacteria are one of the three domains of life on Earth.

behavior: The way something (often a person or other organism) conducts itself or acts towards others.

biology: The study of living things. The scientists who study them are known as biologists.

cell: (in biology) The smallest structural and functional unit of an organism. Typically too small to see with the unaided eye, it consists of a watery fluid surrounded by a membrane or wall. Depending on their size, animals are made of anywhere from thousands to trillions of cells. Most organisms, such as yeasts, molds, bacteria and some algae, are composed of only one cell. (in structures) The term for a small chamber.

environment: The sum of all of the things that exist around some organism or the process and the condition those things create. Environment may refer to the weather and ecosystem in which some animal lives, or, perhaps, the temperature and humidity (or even the placement of things in the vicinity of an item of interest).

infection: A disease that can spread from one organism to another. It’s usually caused by some type of microbe.

insight: The ability to gain an accurate and deep understanding of a situation just by thinking about it, instead of working out a solution through experimentation.

microscope: An instrument used to view objects — such as bacteria or the single cells of plants or animals — that are too small to be visible to the unaided eye.

migrate: To move long distances (often across many countries) in search of a new home. (in science) To travel from one place to another in an attempt to achieve new conditions that may afford stability.

Naegleria fowleri: A single-celled freshwater parasite, sometimes called the “brain-eating amoeba.” It lives in hot springs and other surface waters that get very warm.

nasal cavity: The big open space inside the nose. It sits between the bottom of the skull and roof of the mouth. A mucus membrane lines its walls. This region helps to warm and filter the air we breathe in. And sensory cells within it also can pick up scents and relay that information to the brain.

prey: (n.) An organism hunted by another, often for food. (v.) To attack and eat another organism.

Proceedings of the National Academy of Sciences: A prestigious journal publishing original scientific research, begun in 1914. The journal’s content spans the biological, physical and social sciences. Each of the more than 3,000 papers it publishes each year, now, are not only peer reviewed but also approved by a member of the U.S. National Academy of Sciences.

sediment: Material (such as stones and sand) deposited by water, wind or glaciers.

tissue: Made of cells, it is any of the distinct types of materials that make up animals, plants or fungi. Cells within a tissue work as a unit to perform a particular function in living organisms. Different organs of the human body, for instance, often are made from many different types of tissues.

unique: Something that is unlike anything else; the only one of its kind.