Estudios sobre un cachalote pigmeo, Kogia breviceps (De Blainville, 1838), varado en la costa de Chile

Abstract

Within the cetaceans, exist some genders very little known, due to the scarce possibility of findings, which usually are occasional strands. In these cases it is convenient to get as much information as possible. This report is the first study of a documented Kogia breviceps record for Chilean waters. Includes a description of the strand, as well as an estimation of its age through comparative GLGs (Groups of growth layers) studies by acid etching and polarized light, and the proposal of an image computational counting technique and an hypothesis explaining the bony characteristics of the specimen found. The record corresponds to a K. breviceps, stranded dead on April 1,1995, and its length was of 3.4 m. The known distribution range for K. breviceps is extended from the Peruvian coast south to the central Chilean coast. The dental study shows 19 postnatal GLGs, with advanced wear and abundant osteodentins, why frequently would have included crustaceans or other hard body species in their diet. The specimen has a very reticular bony structure, porous, similar to the observed in mysticetes. Assuming an annual lamination rate, the animal would be 19 years old. Hypothesis: The osteological features would be vinculated to a high growth rale, similar to mysticets in order to increase the thermal inertia. But in opposition to those, the cold waters in which they live, would not be the polar (in latitude) but the deep waters in which they dive.