Mahi-mahi: A large fish that lives in the open ocean in warm parts of the world.
Mammal: A warm-blooded animal that breathes air, has hair and feeds its young with milk.
Mainsail: Main or biggest sail on a sailing vessel.
Management: Process by which conservation is made possible.
Mangrove: A small tropical tree that grows in wetlands at the edge of the ocean. Mangrove forests are habitat for many kinds of fishes and other animals.
Manoeuvre: To control the movement and direction of something, as to manoeuvre a vehicle.
Mantle: A portion of the body wall of a mollusc. In snails, clams and other molluscs with shells, the mantle secretes the shell. In octopus and squid, the mantle is the outside of the body.
Marine: Of the sea.
Marine betta: A small, spotted fish found on coral reefs of the western Pacific.
Marine snow: Organic particles that fall into the deep sea from the sunlit surface waters.
Marine education: The process that teaches people about the cultural, recreational, environmental, commercial and management issues associated with the sea.
Marine pest: Increase in population numbers of a animal or plant that attracts media attention.
Marine Studies: A study of the cultural, environmental, commercial and recreational aspects of the sea and its management.
Marine threat: Potential to carry pest organisms into our country.
Maritime archaeology: Science of preserving ships and shipwrecks.
Maritime museums: Places where marine culture is preserved for public admission.
MARPOL: International convention that deals with marine pollution from ships.
Marsh: A wetland where plants grow with their roots in water and their tops in the air.
Marsh wren: A small songbird that nests in marshes.
Mask: In snorkelling, a covering for the face that helps you to see better underwater.
Mast: An upright spar that supports sails and associated rigging.
Medusa: The umbrella-shaped type of jelly.
Membrane filter: Filter used to catch bacteria to check faecal coliform levels when determining water quality.
Mercury: Liquid used in thermometers. Expands or contracts with changing temperature.
Mesoglea: The layer of gelatinous material that separates the inner and outer cell layers of a coelenterate.
Mesopelagic: The twilight midwater zone 660 to 3,300 feet deep (200 to 1,000 meters), between the upper sunlit zone and the dark ocean depths.
Mesotech sonar: A device on a remotely operated vehicle that's similar to an echo-sounder and shows the bathymetry (hills and valleys) of the seafloor.
Meteorologist: Person who studies and forecasts the weather.
Meter: A length of measurement equal to 100 centimetres. (39.37 inches, or approximately three feet)
Methane: A colorless, odorless gas formed naturally by the decomposition of organic matter.
Microridge: Line of sand that is deposited as wave stops washing up the beach.
Microscope: Instrument used to see very small animals, plants and bacteria.
Microscopic: So small that it can only be seen with a microscope.
Mid-oceanic ridges: Elongated rises on the ocean floor where molten rock periodically erupts, forming new oceanic crust.
Mid-water: A habitat in the deep sea, usually defined as the waters between the sunlit surface and the deep seafloor.
Migration: The periodic movement of animals from one place to another, often between feeding and spawning areas.
Minamata disease: Crippling disorder of humans caused by mercury poisoning from contaminated seafood.
Mirdawarr: Aboriginal term for the end of the wet season.
Mole crab: A small crab that lives buried in sand at the ocean's edge; also called the sand crab. Mole crabs can dig very fast to escape from predators.
Molt: To shed old feathers or hairs so that new ones can grow. Birds molt every year; so do elephant seals.
Module: Part of a certificate course, also referred to as a course element.
Monitor: (verb) to check or gather information. (noun1) A person who checks or gathers information. (noun2) A screen for viewing information, such as a computer monitor.
Moon snail: A species of marine snail that has a large, pale, rounded shell.
Mooring: A fixed fastener or anchor used by boats. Boats using moorings donít have to use traditional anchors this reduces damage to coral reefs.
Morphology: The scientific study of the form and structure of living organisms; or the form and structure itself.
Moulting: In crustaceans, the process whereby outer shell is shed.
Mouthpiece: Forms part of the snorkel placed in the mouth.
Mudflat: A flat area along the coast, covered with a thick layer of mud or sand. Mudflats are usually under water at high tide.
Multiskilled: Ability to do many tasks on a ship, e.g. drive a tender boat, perform first aid, launch a life raft, roll napkins.
Multi-use areas: Areas in a marine park that can be used for different purposes by different groups of people.
Multiculturalism: Term used to describe many cultures and learning to get on with one another with mutual respect.
Mussel: a mollusc similar to a clam but with narrow, dark-colored shells.
Mutualism: A form of symbiosis where both species involved benefit from the partnership.
Mysids: Group of small, shrimp-like crustaceans characterised by possessing a ventral brood pouch.