Should we welcome them? The great white is the most fearsome of all sharks, and the waters off Devon and Cornwall are perfect habitats for it. Some believe it may be here already.
Warming sea lures great whites to UK
Deadly: Researchers say Cornwall will soon provide perfect conditions for sharks like the one above. Glossary
Plankton - A general term for small organisms drifting in the sea or freshwater. Krill fall into the category, and are actually a kind of small shrimp.
Mean - The mathematical average of two or more numbers.