Definitions

Macroclimate the climate of the major geographical regions
Macroevolution Evolutionary change on a grand scale, encompassing the origin of novel designs, evolutionary trends, adaptive radiation, and mass extinction.
Macroscopic something visible to the naked eye or visible through a hand lens
Madreporite The sieve-like structure that is the intake for the water vascular system of echinoderms
Maggot the grub-like larval stage of some insects, e.g. flies
Malacology the study of molluscs
Malacostraca a class in the Crustacea containing the crabs, shrimps, lobsters and woodlice
Mallophaga the chewing/biting lice
Malpighian/Malphigian tubes Excretory organs of insects that empty into the digestive tract, remove nitrogenous wastes from the blood, and function in osmoregulation.
Mandibles the first or uppermost part of the jaw, often used when describing insects
Mandibulates Animals with jaw-like appendages, e.g. many insects and crustaceans.
Mantis shrimp Squilla mantis
Mantle lateral skirt-like fold of the molluscan body wall, usually having a spacious cavity beneath it.
Mantle cavity In molluscs, a cavity between the mantle and the rest of the body. The cavity is filled with water in aquatic molluscs, and often contains the gills.
Mantoidea The sub-order containing the mantises, praying mantis, etc.
Mask The specialised mouthparts of dragonfly and damselfly nymphs. The mask is a modified lower lip with moveable and jointed "jaws". The whole thing can be shot out at great speed to capture prey.
Mason wasp Eumenidae, also known as potter wasps
Maxillae/maxilla the second or lower part of the jaw, often used in describing insects.
Maxillary palp in insects, a leg-like structure arising from the maxilla
Mayfly Ephemeroptera
Mechanoreceptors Sensory receptors that detect physical deformities in the body associated with pressure, touch, stretch, motion and sound.
Meconium the first excreta of a newly emerged adult following the pupal stage
Mecoptera scorpion flies
Mediterranean climate a climate of hot, dry summers and wet, mild winters
Medusa the free-living, sexual, jelly-fish-like stage of certain cnidarians
Megafauna animals large enough to be seen with the naked eye
Melanic darkened
Melanin a black, bownish or dark red animal pigment containing nitrogen
Melanism the opposite of albinism. An undue development of colouring making the animal appear darker then normal. This is quite common in certain bumblebees.
Merostomata Horseshoe crabs, a class in the phylum Chelicerata
Mesoglea The jelly-like substance between the two layers of the body wall in Cnidaria and Porifera.
Mesozoa A phylum of marine endoparasites
Mesothorax the middle segment of an insect's thorax which bears the middle pair of legs and the front wings.
Metabolism the totality of an organism's chemical processes, consisting of catabolic and anabolic pathways.
Metameric a body largely comprising of a series of segments, as in the annelids
Metamerism The division of a body, from front to rear, in a series of segments, each segment containing representative of all the organ systems of the body, as seen in the Annelida.
Metamorphosis an abrupt change in body form from one larval stage to another, or from larva to adult, as seen in some insects.
Metanephridium A type of excretory tube in Annelida that has internal openings called nephrostomes which collect body fluids, and external openings called nephridophores.
Metathorax the second segment of an insect's thorax which bears the third pair of legs and the hind wings
Microclimate The highly localised climate of a strictly limited habitat, e.g. inside a flower.
Microevolution a change in the gene pool of a population over a succession of generations
Microhabitat a small, specialised habitat
Midge a small fly in the Chironomidae family
Migration A journey to a different region, following a well-defined route. Most animals that migrate do so according to seasonal changes to benefit from good breeding, feeding or overwintering conditions.
Millipede an invertebrate in the Class Diplopoda
Mimicry A form of camouflage in which an animal resembles another animal or inanimate object. It is common in insects, e.g. some harmless flies mimic stinging bees or wasps, and stick insects resemble twigs.
Mitochondria Organelles found in eukaryotic cells. The contain the enzymes responsible for aerobic respiration.
Mode of action The mechanism by which an insecticide affects an insect.
Mollusca the phylum containing the slugs, snails, octopus, and other shell-fish
Monerans/Bacteria Are the simplest fully-independent living things. They are prokaryotes, i.e. they lack the specialised structures found in eukaryotes. Energy is obtained from sunlight, organic and inorganic sources.
Monogenea A Class of Platyhelminthes commonly known as flukes
Monogonata A class of rotifers
Monogyny a colony of eusocial insects dominated by one queen, as in bumblebees
Monolectic taking pollen and/or nectar from a single species of flower
Monophyletic evolutionarily derived from a single ancestor, recognized by the joint possession of a shared, derived feature
Monoplacaphora A Class of Molluscs with a single conical shell
Morphospecies species defined by their anatomical features
Morphs two or more distinct forms of individuals in a population
Morphology The study of the form and structure of organisms
Mortality death
Mosquito a fly in the Culcidae family
Moss animal Bryozoa
Moth An insect in the Order Lepidoptera
Motile something that has the capacity for movement
Moult shedding of exoskeleton in order to increase size, as seen in most insects, chelicerata and Crustacea
Mullerian mimicry mutual mimicry by two or more unpalatable species
Multipoint stability the tendency of a population to regain stability at a different level.
Multivoltine having several broods or generations per year, e.g. as in the cabbage white butterfly
Muscidae the family of true flies which contains the house fly and the stable fly
Muscle cells Contract and relax to move the different parts of the animal's body.
Mussel shrimp also known as seed shrimp, a Crustacean in the Ostrocoda Class.
Mutagen an agent that produces or enhances the rate of mutation
Mutant any organism, gene, or character that has undergone a mutational change
Mutation a rare change in the DNA of genes that ultimately creates genetic diversity
Mutualism Symbiosis that benefits the members of both of the participating species.
Mycetophilidae fungus gnats
Myiasis a disease or injury caused by the feeding of larval flies on live flesh
Myrmecochorus dispersed by ants, e.g. seed dispersal
Myrmecology The study of ants.
Myrmecophily the pollination of plants by ants
Myrmeleontidae ant lions
Mystacocarida a Class of Crustacea