Baleen whales: preliminary evidence for forestomach microbial fermentation

Area of Science:

• Marine biology
• Mammalian digestive physiology
• Microbial ecology

Background:

• Baleen whales possess a three-compartment stomach.
• The forestomach, the first compartment, is noncornified and nonglandular.
• Its precise function remains undetermined.

Purpose of the Study:

• To investigate the function of the baleen whale forestomach.
• To determine if microbial fermentation occurs in the forestomach of baleen whales.

Main Methods:

• Analysis of forestomach fluid samples from bowhead (Balaena mysticetus) and gray (Escherichtius robustus) whales.
• Detection and quantification of volatile fatty acids (VFAs).
• Bacterial enumeration and assessment of digestive tract morphology.

Main Results:

• Volatile fatty acids (acetic, propionic, butyric, valeric, isobutyric, isovaleric, and isocaproic acids) were detected in forestomach samples.
• Bacterial populations ranged from 5 X 10(8) to 630 X 10(8)/ml.
• The presence of VFAs and bacteria, alongside forestomach morphology, suggests fermentation.

Conclusions:

• The findings support the hypothesis of microbial forestomach fermentation in bowhead and gray whales.
• This process may play a role in nutrient absorption or processing in these species.
• Further research is warranted to fully elucidate the digestive role of the baleen whale forestomach.