View larger version (29K):
[in a new window]
|
Fig. 1. Morphology of balaenid head. Schematic lateral views showing the narrow,
arched rostrum and huge, scoop-shaped, lower jaw with mouth closed (A) and
open, in feeding position, with abducted lips (B). (A) When the mouth closes
the baleen folds back, the lip overlaps the upper jaw, and the central furrow
of tongue (light broken lines) contacts the palate. Heavy broken lines
indicate the orolabial sulcus between tongue and lip; the dotted line denotes
oropharynx and esophageal orifice. (B) In the less streamlined open-gape
feeding profile, note the large lower lip above the mandible (broken line) and
the overlapping extent of the freely suspended baleen rack (dotted line), with
the shortest plates at rear. The arrow indicates where filtered water exits
posterior to the lip after passing along the gutter-like orolabial sulcus.
|
1 m).