Meeting Abstract

P2.66  Jan. 5  Functional Morphology of Inking Behavior in Pygmy & Dwarf Sperm Whales MARSHALL, CD; MOSS, AL*; Texas A&M University marshalc@tamug.edu

Pygmy & dwarf sperm whales (Kogia breviceps and K. sima) demonstrate an unusual inking behavior similar to cephalopods. Such behavior is unknown among other cetaceans. The source of ink is hypothesized to be the production of a large volume of watery stool (12-50 l). Evidence suggests that the mechanism for ink production kogiids is a derived digestive physiology in the enlarged, sac-like colon. A systematic investigation of kogiid gastrointestinal (GI) tracts has not been conducted. Therefore, this study investigated the morphology and cytology of the kogiid GI tract. Five GI tracts were collected through the SEUS Stranding Network. Standard morphometrics of the GI tract were taken (length, diameter, and volume), and samples were process for histology, and then stained with a modified Masson�s trichrome. Morphometrics of epithelia were taken and enterocytes were identified and quantified (e.g., height & width of villi, thickness of mucosa & adjacent tissue layers, and the factor of the increase in absorptive surface area). The mean length of the jejunum and colon were 23.3 m and 2.26 m, respective. External lengths of the duodenum and ileum were arbitrary due to the lack of external distinctions between adjacent segments. Mean diameter of the duodenum, jejunum, and colon, were 2.28, 1.93, and 7.84 cm, respectively. Mean volume of the duodenum, jejunum, and colon were 220, 8,693.2, & 1,398.9 ml³, respectively. Maximum colon diameter and volume was 16.5 cm & 1771.5 ml³. Plicae and villi of the jejunum and colon were remarkably limited, short and exhibited a low surface area relative to bottlenose dolphins. Mucous cells dominated both the jejunum and the colon. We hypothesize that the normal function of the colon, has been disrupted to produce large volumes of ink.