Science / Marine Biology Glossary

Phosphoresence: See Bioluminescence.

Photic Zone: The surface layer of the ocean that is penetrated by sunlight. The photic zone is the layer of the ocean that has been explored the most as it is relatively easy to access with conventional . . . View Full Definition

Photorespiration: Enhanced respiration of plants in the light relative to dark respiration

Photosynthate: A substance synthesized in the process of photosynthesis

Photosynthesis: A chemical process whereby plants and algae use a sun's energy to make sugars (organic compounds) from carbon dioxide and water (inorganic compounds). See also autotroph, chemosynthesis.

Photosynthetic Quotient: In photosynthesis, the moles of oxygen produced, divided by the moles of carbon dioxide assimilated

Photosynthetic Rate: The rate of conversion of dissolved carbon dioxide and bicarbonate ion to photosynthetic product

Phototactic: Moving in response to light

Phylum: The broadest classification for animals. Compare species.

Physiological Race: A geographically defined population of a species that is physiologically distinct from other populations

Phytoplankton: The plant and algae component of the plankton; the primary producers of almost all marine food webs. Compare zooplankton.

Planktivorous: Feeding on planktonic organisms

Plankton: Pelagic organisms that float through the water column, not attached to any substrate and unable to move against the currents and tides. Plankton can be further divided into phytoplankton and . . . View Full Definition

Planktotrophic Larva: Planktonic-dispersing larva that derives its nourishment by feeding in the plankton

Planula: The planktonic larval form produced by scleractinian corals and coelenterates

Plate: Major section of the earth's crust, bounded by such features as mid-ocean ridges

Pleistocene: Period of time, going back to approximately 2 million years before the present, in which alternating periods of glaciation and deglaciation have dominated the earth's climate

Pleuston: Refers to plankton that have a float protruding above the sea surface, such as the Portugese man-of-war.

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