Other behaviors observed during bouts, but not quantified because of infrequent occurrence, included 1) gaping--repeated opening and closing of the mouth in a stationary frog; 2) front leg lifts--raising and lowering of the front leg; 3) sitting up--elevation of the anterior portion of the body and head; and 4) partial inflation of the vocal sac
without sound production--this usually occurred after a vocalization, so that the vocal sac
was not collapsed completely once a call was finished, or before a vocalization, so that the vocal sac
was inflated for a time before a call began.
These extra harmonics were eliminated or greatly attenuated if the larynx was activated with the mouth closed and the vocal sac
was allowed to inflate (Figure 6).
Males of this species have paired vocal slits opening into a single vocal sac
. Dentigerous processes of the vomer are absent.
Both share a small size (less than 40 mm snout-vent length), largo and bulgy eyes directed somewhat rostrally, green bones, smooth and brownish dorsal skin, relatively short and truncate snout, small tympanum, subgular and laterally expanded vocal sac
, poorly developed subarticular and supenumerary tubercles, a supra-anal glandular ridge, and cream-white venter and subocular region.
Dorsum, chest, and gula smooth; belly skin granular; vocal sac
prominent tending to be bilobed when inflated; an incomplete chest fold, folds of skin at wrist, knee and heel; axillary membrane small.
He and his colleagues have videotaped a frog hopping over to Roborana, pouncing on top of the robot, and swiping at the vocal sac
. With this new tool, Narins hopes to tease out more about how frogs interpret these signals.
A throat pouch called a vocal sac
swells up like a balloon.
That big bubble under the tree frog's throat is his vocal sac
. When the sac fills with air, the sound of the frog's call bounces around inside and grows louder.
Its skull shows that the big primate had an enlarged vocal sac
, which it used to communicate over long distances, as howler monkeys do today.