13 Glossary

GLOSSARY ALGAE a group of plant-like organisms, most of which live in water ALGAL BLOOM a rapid increase in the growth of algae ASTRONAUT a person who has been trained to travel into space BARNACLE a shelled sea creature that attaches itself tightly to rocks and other surfaces BIOLUMINESCENCE when a living organism produces its own light CHARLES DARWIN English naturalist who studied animals and plants

CONSTELLATION a group of stars that form a pattern FOSSIL FUELS the remains of organisms that died millions of years ago that can be burned to release energy GLOBAL WARMING an increase in global temperature due to high greenhouse gas levels GREENHOUSE GAS a gas in the atmosphere that traps the sun's warmth around the planet, such as carbon dioxide and methane HARBOR a place on the coast where boats can dock HORIZON the line where the sky seems to meet the sea

KRILL small shrimp-like animal eaten by many sea creatures, including whales MARINE BIOLOGIST someone who studies ocean life MIGRATION when animals make a long, regular journey from one place to another POD a name for a group of whales POLLUTION something harmful that gets into the air, a water source, or the soil SCHOOL a group of fish swimming together SONAR a system that locates things underwater or in the air using sound echoes

SUBMARINE a ship designed to work underwater TADPOLE a young frog or toad WATER PRESSURE the amount of pressure exerted by water. Water pressure increases the deeper you dive WET SUIT a close-fitting piece of clothing worn while diving