Name: Motoro Ray
Scientific name: Potamotrygon motoro
Range: Amazon Basin
Habitat: freshwater rivers
Status: not considered an endangered species
Diet in the wild: consists of crustaceans, mollusks, and small
fish which swim near the bottom.
Diet in the zoo: earthworms
Location in the zoo: James
R. Record Aquarium
max size: 45cm (18 inches)
Body length up to 18 inches.
Weight 8-10 lb.
Color is golden with dark spots.
Tail has a barb on the base.
Ears are just behind the eyes.
The motoro is one of three main species of the Potamotrygonidae
family. The three main genera of freshwater stingrays from South America
are Potamotrygon, Plesiotrygon and Paratrygon. The motoro ray is
in the species Potamotrygon. The origin of the Potamotrygon is that
they are usually neotropical river stingrays that have adapted to freshwater
by using a salt secreting rectal gland as well as a suppressed concentration
of urea in body fluids. These stingrays are normally found at the bottom
of rivers feeding on almost anything on the river bottom. The typical
diet in the wild is mainly small fishes, insects and crustaceans.
They also posses a powerful sting that can cause severe pain that normally
requires medical attention. The stingers are replaced up to three times
a year. The species are typically not very fast swimmers. The
technique used in order to capture prey is to trap the prey under its disc,
then slowly adjusting its mouth to the trapped prey until they can swallow
Stingrays are in general considered to be a group that is known for
intelligence. Stingrays are agile and extremely graceful swimmers, but
the majority of the time in a motoro's life is spent hiding by lying almost
completely covered in sand on the river bottom waiting for prey to swim
by. Since the motoro does not use speed to catch prey it must rely on
its coloration. The motoro's color patterns provides the ray
with the adequate camouflage needed while waiting for its next meal to
swim by. To this day it is largely considered a mystery on the migration
patterns of the motoro
|Special anatomical adaptations:
key adaptation that the motoro ray possesses is that its gills are located
on the top of the head. This adaptation allows the motoro to breathe comfortably
while waiting under the sand for food. Although the stingray does
have a poisonous stinger the stingray is a very gentle and peaceful animal.
The sting it delivers is a painful one, but the motoro is definitely not
aggressive toward humans. The primary use of its stinger is in self-defense.
More often then not the cause of a human to be stung by one of these gentle
creatures is if they are stepped on. One way to prevent this from
happening is for people to shuffle their feet while traveling in areas
of water that may be inhabited by rays. There is no surprise that
people step on these creatures because they do lie motionless buried in
the sand, and they are very well camouflaged. When a motoro is stepped
on it subconsiously elicits a reflex response that causes the ray to raise
its tail and extend the stinger perpendicularly. People who are stung are
usually stung in the calf area.
Rays of the Fort Worth Zoo:
It is sad for me to say that one of the Ft. Worth Zoo's motoros died
early in November this year. It became lodged between a tree and
the wall of the tank. Fortunately the other motoro is still very
healthy. The zoo is curently looking for a male that they can breed
with the female that they currently have.
The motoro at the zoo acts much like it would if it was in nature.
It sits on the bottom of the tank ignoring the other fish.
at the Fort Worth Zoo