Glossary - M
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M

magnetic resonance imaging (MRI)
method of producing a three-dimensional image of object by recording the signals the object emits when placed in a magnetic field
manatee
Trichechus spp.
mandible
one of the jaw structures of animals. For example, in vertebrates, it is the lower jaw bone; in insects it is one of the anterior mouth parts.
masking
acoustic interference that reduces the ability to detect, recognize, or understand sounds of interest.
mass stranding
a stranding event where 2 or more animals, excluding mother-calf pairs, unless a third animal strands, strand together in time and place.
mean
the average of a set of measurements defined to be the sum of all of the measurements divided by the number of measurements.
mechanoreceptors
sensory organs that cause response to displacement, pressure and vibrations
medium
substance or material that carries or transports the wave from its source to other locations. In the open ocean, the medium through which the wave travels is the ocean water.
melon
lipid-filled sac in the forehead of whales that helps to focus sound
mesopelagic boundary community
small (less than 4 inches long) fishes, shrimps, and squids that live in the middle of the water column and near islands
metamorphosis
the process of transformation from an immature form to an adult form.
mid-ocean ridge
underwater mountain chain where new ocean crust is created.
middle ear
the air-filled cavity that lies between the outer ear and the inner ear. The middle ear contains the ossicles which conduct sound vibration from the eardrum to the inner ear.
migration
movement of a group of animals from one location to another
minke whale
Balaenoptera acutorostrata
miss
Incorrectly deciding on the basis of a statistical test that a signal is absent when it is in fact present. A false negative.
mitigate
to make (something) less severe or harmful.
molt
to shed the outer covering, or shell, which is then replaced by a new shell that is produced by the organism
mooring
equipment (often consisting of anchors and chains) which holds an item (such as a boat or underwater instrument) stable and secure in one place
morphology
the form and structure of an organism or any of its parts
mudflat fiddler crab
Uca rapax
multi-channel seismics
using multiple hydrophone arrays or streamers to record the reflected and refracted sounds from an air gun array
Mysticetes
These large cetaceans are usually more than 9.1 m (30 ft) long and can be found throughout the ocean. Instead of teeth, mysticetes have a series of horny plates called baleen. The baleen is made from the same materials as human hair and fingernails. The baleen plates hang from the gums of the upper jaw and are used to filter small bits of food from the water. Baleen whales have symmetrical skulls and have two (or paired) blowholes.