Definição: A taxon is Data Deficient when there is inadequate information to make a direct, or indirect, assessment of its risk of extinction based on its distribution and/or population status. A taxon in this category may be well studied, and its biology well known, but appropriate data on abundance and/or distribution are lacking. Data Deficient is therefore \r\nnot a category of threat. Listing of taxa in this category indicates that more information is \r\nrequired and acknowledges the possibility that future research will show that threatened \r\nclassification is appropriate. It is important to make positive use of whatever data are available. In many cases great care should be exercised in choosing between DD and a threatened status. If the range of a taxon is suspected to be relatively circumscribed, and a considerable period of time has elapsed since the last record of the taxon, threatened status may well be justified.
Definição: a type of pectoral-fin-based swimming, also known as mobuliform locomotion. Lower frequency than fin undulation; can be described as the production of less than half a wave on the fin, similar to a bird wing flapping. Pelagic stingrays use oscillatory locomotion.
Definição: Capable of creating a new organism by combining the genetic material of two gametes, which may come from two parent organisms or from a single organism, in the case of self-fertilizing hermaphrodites.
Definição: Two types of males, namely, primary males and secondary males coexist in diandric protogynous fishes. Secondary males are derived from females through sex change, i.e. they are protogynous hermaphrodites. In contrast, primary males are considered to be born males and do not change sex. Both young primary males (Initial Phase) and females may mature into Terminal Phase males, which have breeding priority.
Definição: National Museum of Natural History, Smithsonian Institution (USNM), Washington, District of Columbia, USA.\r\nNMNH and USNM both refer to the National Museum of Natural History. Collections are associated with one or the other acronym. US, the US National Herbarium, is a collection within the National Museum of Natural History. URL for main institutional website, http://www.mnh.si.edu/rc/\r\nURL for institutional specimen catalog, http://collections.mnh.si.edu/
Definição: Relative to pinhole eyes, lens eyes have greatly improved resolution and image brightness. The lens converges incoming rays of light, thereby reducing the angle over which each photoreceptor receives light, and forming an image focused on the retina. Most lens eyes have "accommodation"; they can focus an image either by physically moving the lens toward or away from the retina or by using eye muscles to adjust the shape of the lens.
