Alkaline: Acting like a base; having a pH of more than 7.

Anaerobic: Without oxygen.

Benthic: Living in or on the bottom of a body of water.

Benthos: Those organisms that live in or on the bottom of a body of water. The benthos is one of three divisions of aquatic life; the others are the nekton and the plankton.

Bivalves: an animal (as a clam or oyster) with a 2-valved shell.

Brackish: somewhat salty water.

Brood: to incubate eggs until hatching.

Budding: pinching off of a small part of the parent to form a new organism, a form of asexually reproduction.

Cardinal teeth: ridges or grooves that help hold the shells in alignment.

Carapace: The protective hard shell-like shield that covers the back of an animal (such as a crab or a turtle).

Carnivore: An animal that eats other animals.

Chlorophyll a: A photosynthetic pigment that serves as a surrogate measure for abundance of algae.

Colloquial: regional slang.

Coriolis Effect: The tendency for any moving body on or above the earth's surface, such as a water current, to drift sideways from its course because of the earth's rotation. The Coriolis Effect occurs because the speed of a point on the earth?s surface is greater for point near the equator than for a point near the poles. In the Northern Hemisphere the deflection is to the right of the motion Thus saltwater moving north up the Chesapeake Bay is deflected to the east, and freshwater moving south down the Bay is deflected to the west, resulting in higher salinities on the Eastern Shore of Maryland than on the Western Shore at the same latitude.

Ctenophore: A comb jelly, a transparent gelatinous planktonic animal. Comb jellies have rows of cilia that look like combs. Unlike sea nettles and other jellyfish, comb jellies do not have stinging cells.

Cuticle: Non-cellular outer portion of the integument (skin).

Cyanobacteria: Formerly called blue-green algae or cyanophytes

Estuary: A semi-enclosed body of water where saltwater mixes with fresh water such as the Chesapeake Bay.

Fertilized/Fertilization: the union of a female gamete (egg) with a male gamete (sperm).

Hermaphroditic: an animal or plant having both male and female reproductive organs.

Holometabolous order: having/undergoing complete metamorphosis during development; the stages include egg, larva, pupa and adult..

Indicator species: a species whose status provides information on the overall condition of the ecosystem and of other species in that ecosystem. Indicator species reflect the quality and changes in environmental conditions as well as aspects of community composition.

Intertidal: the portion of the shoreline that is underwater during an average high tide and exposed at an average low tide.

Marsupium: structures in invertebrates for enclosing or carrying eggs or young.

Mesohaline: moderately brackish water with a salinity range of 5-18 ppt.

Nekton: The nekton includes all aquatic animals that actively swim in the water column, such as fish or squid. The nekton is one of three divisions of aquatic life; the others are the plankton and the benthos.

Molt / Molting: A process where crustaceans and insects shed their exoskeleton (external support).  This is an important growth process, enabling the animal's body to expand.

Oligohaline: slightly brackish water with a salinity range of 0.5-5 ppt.

Parapodia: fleshy paddle-like appendages on each segment of a polychaete’s body.

Periostracum: the flaky leathery outer covering on shells that protects from eroding or dissolving.

Phytoplankton: a type of plant plankton, such as algae, that is the basic food source in many aquatic and marine ecosystems.

Plankton: The plankton includes all aquatic organisms that are carried passively in the water currents. Most are microscopic (such as diatoms, dinoflagellates, and copepods), but others can be relatively large (such as comb jellies and sea nettles). Plankton is one of three divisions of aquatic life; the others are the nekton and the benthos.

Polyhaline: highly brackish water with a salinity of range 18-30 ppt.

ppt: an abbreviation for parts per thousand and a measurement of salinity. For example, the open ocean is 35 parts per thousand (ppt). This means that if you had 1,000 buckets of sea water, and could put salt and water in separate buckets, 35 of the buckets would be filled with nothing but salt.

Protists: Protists are single-celled eucaryotic organisms in the Kingdom Protista, also called the Kingdom Protoctista. The five kingdoms in R.H. Whittaker's taxonomic system are the procaryotes (procaryotic organisms, including the bacteria and cyanobacteria), protists, fungi, plants, and animals. "Animal-like" aquatic protists (such as copepods) are often called protozoans or zooplankton. "Plant-like" aquatic protists (such as diatoms) are commonly called phytoplankton. However, the protist biologist Lynn Margulis points out that "these organisms are no more "one-celled animals and one-celled plants" than people are shell-less multicellular amebas."

Pupa (plural is pupae): The stage in holometabolous insects that occurs after the larval stage, during which the insect metamorphoses into the adult form.

Pycnocline: The pycnocline is the depth in the water column where there is an abrupt change in density, temperature, and salinity. A pycnocline often forms in the Chesapeake Bay and its tidal tributaries when the lighter, warmer, and fresher water coming downstream from the spring rains overlays the denser, colder, and saltier water of the salt wedge bringing water upstream from the ocean.

Sessile: not free to move around; sedentary.

Setae: hair-like bristles mostly used for locomotion.

Spawning/Spawn: a form of sexual reproduction where microscopic eggs and sperm are discharged into the water column.

Subtidal: the zone of the shoreline that is below low tide and is always covered by water.

Tidal freshwater: freshwater (0-0.5 ppt) that is tidally influenced.

Ventral: located near or on the lower surface of an animal opposite the back, the belly region.

White Cardinal Teeth: Ridges or grooves that help hold the two shells or ?valves? of a bivalve in alignment.