Zoology glossary ~ R

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Reindeer
Reindeer

Rachis
The rachis is the section of the central shaft of a feather to which the vanes are attached.

Radiation
"The evolution of several closely related species from a single ancestor, especially when the species evolve morphological differences that allow the coexistence or spread of the species to occupy many differnent habitats or ecological roles."

Radula
A rough, raspy tongue used to grate food, characteristic of most mollusks.

Range
"The geographic area or spatial distribution in which a species is normally found."
Rare
"Present in a given location but unlikely to be seen without considerable effort, usually because the species is found in small numbers or because (for nonresident species) it is present in only some years."

Rattle
Loosely interlocking remnants of shed skin, present on a rattlesnake's tail, that are vibrated to make a rattling sound to deter predators.

Rectrices
"The long flight feathers of the tail."

Reducing Atmosphere
Reducing Atmosphere

Remiges
"The long flight feathers of the winbs."

Reptilia
The class of vertebrates whose members have dry skin with scales and reproduce by amniotic eggs. This class includes snakes, lizards, and alligators.

Resident
"A nonmigratory species that completes its annual cycle within a fixed area."

Reticulated
Arranged in a network pattern.

Reverse Migration
"A phenomenon in which migrating individuals orient in the direction opposite the normal one for the species at that season."

Rictal Bristles
"Stiff, hair-like modified contour feathers that occur in a row and project from each side of the corners of the mouth (ritus)."

Riparian
"Associated with rivers and streams."

River Dolphins
A group of dolphins that live in the major rivers of the world, including the Amazon in Brazil, the Ganges in India, the Yangtze in China, and the Irrawady in Myanmar, to name a few.

Rostral Scale
Scale at the very tip of the snout on the upper jaw.

Rostrum
An anatomical structure that projects from the head of an animal, such as a snout.

Rounded
"The shrtest version of an elliptical egg shape; spherical."