Glossary of Terminology: U

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Number of records found : 37

U.S. coral reef jurisdictions - fifteen US coral jurisdictions are found across the US and Pacific Freely Associated States. From East to West, the six Atlantic/Caribbean/Gulf of Mexico jurisdictions are the U.S. Virgin Islands (USVI), Puerto Rico, Navassa Island, Southeast Florida, the Florida Keys, and the Flower Garden Banks National Marine Sanctuary, and other banks of the northwestern Gulf of Mexico. In the Pacific, the nine jurisdictions are the Main Hawaiian Islands (MHI), the Northwestern Hawaiian Islands (NWHI), American Samoa, the Pacific Remote Island Areas (PRIAs), the Republic of the Marshall Islands (RMI), the Federated States of Micronesia (FSM), the Commonwealth of the Northern Mariana Islands (CNMI), Guam, and the Republic of Palau

U.S. Coral Reef Task Force (USCRTF) - established by President Clinton in June, 1998, through Executive Order 13089 on Coral Reef Protection, to lead the U.S. response to this growing global environmental crisis. Chaired by the Secretary of the Interior and the Secretary of Commerce, the USCRTF is composed of the heads of 11 federal agencies and the Governors of 7 states, territories or commonwealths with responsibilities for coral reefs. The USCRTF is responsible for overseeing implementation of the Executive Order, and developing and implementing coordinated efforts to: map and monitor U.S. coral reefs; research the causes and solutions to coral reef degradation; reduce and mitigate coral reef degradation from pollution, overfishing and other causes; and implement strategies to promote conservation and sustainable use of coral reefs internationally

U.S. Pacific Remote Insular Area (PRIAs) - PRIAs consist of the following islands and coral reefs appurtenant to such island, reef or atoll, as applicable: Baker Island, Howland Island, Jarvis Island, Johnston Atoll, Kingman Reef, Wake Island, and Palmyra atoll

ubiquitous - having a worldwide distribution; common to abundant in a given area

ulcer - an open lesion on the skin or an internal mucous surface resulting in necrosis of tissue

ulceration - the development of an ulcer

ultimate - last or farthest

ultramarine - deep blue color

ultrasonic - sound waves that have frequencies higher than what humans can hear, usually greater than 20,000 Hz. Some animals such as bats, a species of cave bird, and cetaceans use these high frequency ultrasonic sounds for communication and navigation

ultraviolet radiation (UV) - the region of the electromagnetic spectrum consisting of wavelengths from 1 to 400 nm

Image of bivalve shell

A bivalve shell: 1 = umbo; 2 = periostracum (the pigmented outermost layer of the shell). (Photo: Rick Gillis, Ph.D., Biology Dept., University of Wisconsin-La Crosse)

umbo - the earliest part of a bivalve or brachiopod shell; in bivalves, it is the most dorsal section of the shell, while in brachyopods, it is the most posterior

umbraculiform - umbrella-shaped

Image of jellyfish

The transparent umbrella of this jellyfish makes it less obvious to predators.

umbrella - describes the body of a jellyfish or medusa

umbrella species - in conservation biology, species with large area requirements. Conservation of these species should automatically conserve a host of other species

unavailable name - in taxonomy, a name which does not meet all mandatory provisions of the International Code of Zoological Nomenclature and thus has no status in nomenclature. Unavailable names include: nomen oblitum, nomen negatum, nomen nudum, nomen nullum, nomen vetitum

uncinate - hooked at the tip

undercurrent - a current below another current, or beneath the surface

underwater dB - the unit used to measure the intensity of an underwater sound. Underwater dB refers to "decibels referenced to 1 microPascal," which is abbreviated as "dB re 1 µPa." Sound intensity given in underwater dB is not directly comparable to sound intensity give

undulating - moving in waves

undulipodium - a long or short hair-like extension of the cell membrane of a eukaryote cell used for locomotion or propelling fluids over the surface of the cell body; undulipodia is a collective term for flagella and cilia

unique-event polymorphism (UEP) - an allele for which all copies are derived from a single genic mutational event. It is probable that all individuals who share the mutation will have inherited it from the same common ancestor, and the same single mutational event

uniramous appendage - a type of appendage that is characteristic of insects and other members of the arthropod subphylum Uniramia. It consists of an unbranched series of segments

unite - in taxonomy, to combine or join two or more taxa

univalve - a an animal which has a shell composed of a single piece (snails, limpets), as opposed to a bivalve, which has a shell composed of two pieces (clams, oysters, scallops)

unpublished name - in taxonomy, any name which has not been printed and circulated to meet the criteria of publication as stated by the International Code of Zoological Nomenclature

unused name - in taxonomy, an available senior synonym that is not known to have been used as a valid name in the past 50 years

unzip - a method for uncompressing files on a PC after downloading them from the Internet. Many files are stored on servers in a compressed format, making them take up less disk space, and reducing the time it takes to download them. These files must be decompressed to make them usable by your computer. WinZip and pkunzip are popular free software programs that will uncompress files

upload - transferring data (usually a file) from the computer you are using to another computer. The opposite of "download"

upstream - toward the source or upper part of a stream or current; against the current

upwelling - the process by which warm, less-dense surface water is drawn away from a shore by offshore currents and replaced by cold, denser water brought up from the subsurface

Diagram of uracil

Diagram of the chemical structure of uracil, one of the four nitrogenous bases in RNA.

uracil - one of the four bases in RNA. The others are adenine, guanine, and cytosine. Uracil replaces thymine, which is the fourth base in DNA. Like thymine, uracil always pairs with adenine

urban area   - an area in which a majority of the people are not directly dependent on natural resource-based occupations

urea - a waste product of metabolism eliminated via the kidneys. In elasmobranchs (sharks, rays, skates), urea is found in the blood where it helps to maintain osmotic balance

URL (Universal Resource Locator) - a website address, such as:

Image of orange tunicate

Orange colonial tunicates (Urochordata) at Gray's Reef National Marine Sanctuary.

Urochordata (Tunicata) - a subphylum of the animal phylum Chordata that contains the ascideans (sea squirts). Most adults are sessile and bear little resemblance to the other chordates. They are common inhabitants of coral reefs and mangrove roots

Image of ventral side of crayfish

Ventral view of crayfish. (Photo: Copyright LTTM 2003)

uropod - fan-shaped, paired posterior abdominal appendage in certain crustaceans, e.g., lobsters or shrimp, that are used for swimming

uvelloid - resembling a small cluster of grapes