A white, lobular mass was found in the right ovary of a pregnant Risso's dolphin (Grampus griseus) at necropsy. The mass was unilateral and occupied most of the pre-existing ovarian tissue. Histologically, the mass was composed of diffuse sheets of polyhedral cells with abundant eosinophilic cytoplasm and oval nuclei, separated by fibrous connective tissue. Only a few ovarian follicles were obs...

Auditory evoked potential (AEP) procedures have been increasingly used to measure hearing processes in aquatic mammals. They have been demonstrated to be useful in measuring the audiograms of stranded animals like infant sperm whales (Physeter macrocephalus) and Risso’s dolphins (Grampus griseus). Modulation rate transfer functions (MRTF) demonstrating appropriate stimulus presentation rates ar...

The probability of detecting echolocating delphinids on a near-seafloor sensor was estimated using two Monte Carlo simulation methods. One method estimated the probability of detecting a single click (cue counting); the other estimated the probability of detecting a group of delphinids (group counting). Echolocation click beam pattern and source level assumptions strongly influenced detectabili...

Natural hybridization occurs rarely in mammals, but it is thought to have the potential to produce viable hybrid offspring in cetaceans more easily than in other mammals. Among cases of cetacean hybridization, hybrids between bottlenose dolphins (Tursiops truncatus) and Risso’s dolphins (Grampus griseus) have been documented in both the wild and in captivity. However, until now, no molecular ev...

In early 2004 and in 2005, several unusual stranding events occurred Taiwan during a period when large-scale naval exercises were conducted on nearby waters. Gross examination of the partial remains two carcasses (a ginkgo-toothed beaked whale (Mesoplodon ginkgodens) pygmy killer (Feresa attenuata)) an intact Risso’s dolphin (Grampus griseus) revealed that former had internal injuries to struct...

OBJECTIVES The temporomandibular joint (TMJ) in cetaceans is largely uncharacterized. This study aims to describe the macroscopic, microscopic, biochemical and biomechanical features of the TMJ of two species of the suborder Odontoceti: the harbour porpoise (Phocoena phocoena) and Risso's dolphin (Grampus griseus). Furthermore, we aim to elucidate the structure-function relationship of their TM...