Kane, Emily A. (2009-05). Behavioral Performance and Evolution of Feeding Modes in Odontocetes. Master's Thesis. Thesis uri icon

abstract

  • Vertebrate evolution has resulted in a diversity of feeding mechanisms. Cetaceans are secondarily derived tetrapods that have returned to a marine habitat. As a result, they display feeding modes that have converged with more basal aquatic vertebrates, but display a diversity of new solutions and adaptations. To begin to explore the diversity of feeding adaptations among odontocetes, kinematics of feeding modes and feeding adaptations for belugas (Delphinapterus leucas), Pacific white-sided dolphins (Lagenorhynchus obliquidens), and long-finned pilot whales (Globicephala melas) were characterized. In addition, direct measurements of intraoral pressure were collected to determine maximum suction performance. Characters from these analyses were combined with data for other odontocetes, and were mapped onto a phylogeny of Odontoceti to begin to explore where changes in feeding modes took place. Feeding modes were diverse in belugas, Pacific white-sided dolphins, and pilot whales and included suction, ram, and a combination of both. In general, four phases were observed: (I) preparatory, (II) jaw opening, (III) gular depression, and (IV) jaw closing. Suction was a large component of the prey capture method in belugas and subambient pressures in excess of 100 kPa were generated. Belugas were also capable of lateral lip gape occlusion and anterior lip pursing to form a small anterior aperture. Pacific whitesided dolphins relied on ram to capture prey. However, some degree of pursing and resultant subambient pressure was observed that was likely used to compensate for high ram speeds or for prey manipulation and transport to the esophagus. Pilot whales were more similar to belugas in kinematics, but maintained high approach velocities and did not generate significant suction pressures; suction and ram were used in combination. Belugas and pilot whales appeared to employ hyolingual depression as a primary suction generation mechanism, whereas Pacific white-sided dolphins relied on fast jaw opening. Ancestral state reconstructions indicated that suction feeding capability evolved independently at least six times within Odontoceti. These results indicate the diversity of feeding behaviors in odontocetes and provide directives for future studies on the diversity of feeding in secondarily aquatic mammals.
  • Vertebrate evolution has resulted in a diversity of feeding mechanisms.
    Cetaceans are secondarily derived tetrapods that have returned to a marine habitat. As a
    result, they display feeding modes that have converged with more basal aquatic
    vertebrates, but display a diversity of new solutions and adaptations. To begin to
    explore the diversity of feeding adaptations among odontocetes, kinematics of feeding
    modes and feeding adaptations for belugas (Delphinapterus leucas), Pacific white-sided
    dolphins (Lagenorhynchus obliquidens), and long-finned pilot whales (Globicephala
    melas) were characterized. In addition, direct measurements of intraoral pressure were
    collected to determine maximum suction performance. Characters from these analyses
    were combined with data for other odontocetes, and were mapped onto a phylogeny of
    Odontoceti to begin to explore where changes in feeding modes took place. Feeding
    modes were diverse in belugas, Pacific white-sided dolphins, and pilot whales and
    included suction, ram, and a combination of both. In general, four phases were
    observed: (I) preparatory, (II) jaw opening, (III) gular depression, and (IV) jaw closing.
    Suction was a large component of the prey capture method in belugas and subambient
    pressures in excess of 100 kPa were generated. Belugas were also capable of lateral lip
    gape occlusion and anterior lip pursing to form a small anterior aperture. Pacific whitesided
    dolphins relied on ram to capture prey. However, some degree of pursing and
    resultant subambient pressure was observed that was likely used to compensate for high
    ram speeds or for prey manipulation and transport to the esophagus. Pilot whales were
    more similar to belugas in kinematics, but maintained high approach velocities and did not generate significant suction pressures; suction and ram were used in combination.
    Belugas and pilot whales appeared to employ hyolingual depression as a primary suction
    generation mechanism, whereas Pacific white-sided dolphins relied on fast jaw opening.
    Ancestral state reconstructions indicated that suction feeding capability evolved
    independently at least six times within Odontoceti. These results indicate the diversity
    of feeding behaviors in odontocetes and provide directives for future studies on the
    diversity of feeding in secondarily aquatic mammals.

publication date

  • May 2009