Blainville's Beaked Whale

Map represents approximate range of the species.

Head Shape The melon is relatively flat and merges seamlessly into the thick, moderately long rostrum. There is a prominent stepped arch at the midpoint of the mouthline that rises above the upper rostrum; in females this arch is less pronounced. Coloration Adult males are dark gray dorsally and ventrally. Adult females and juveniles are medium gray on the dorsal surface and white ventrally. Sexually mature males often exhibit linear scarring from antagonistic sparring. Both sexes may have oval scars, usually attributed to the cookie cutter shark, Isistius brasilensis. Size Adult body length ranges between 4.0 to 4.7 m. Recorded maximum body length for adult males and females is 4.7 m and 4.2, respectively. Length at birth is approximately 2 m. Most Likely Confused With: Mesoplodon bowdoini Mesoplodon carlhubbsi Mesoplodon ginkgodens Mesoplodon peruvianus Mesoplodon stejnegeri

Diagnostic features of the skull and mandible On the vertex of the dorsal skull the premaxillary bone extends forward of the nasal and frontal. Separates from Berardius and Ziphius. A sulcus (groove) running along the middle of the combined surfaces of the nasal bones so depresses their middle that it is the lateral portion of each nasal bone that reaches farthest forward on the vertex. Separates from Tasmacetus and Indopacetus. When the skull is upright and the long axis of the anterior half of the beak is horizontal, a horizontal plane transecting the summit of either maxillary prominence transects the mesethmoid bone. Separates from Hyperoodon. Tooth alveoli of mandible are posterior to the mandibular symphysis. Separates from Berardius, Ziphius, Tasmacetus, Indopacetus, Hyperoodon, M. bidens, M. bowdoini, M. carlhubbsi, M. europaeus, M. grayi, M. hectori, M. layardi, M. mirus, M. perrini, and M. traversii. On the vertex the right premaxilla extends posteriorly beyond the right nasal a distance exceeding 70% of dorsal length of right nasal. Separates from M. ginkgodens. Antorbital notches form obtuse angles. Separates from M. peruvianus. A transverse plane perpendicular to the long axis of the rostrum and transecting the apex of the left antorbital notch, the anterior most point reached by the pterygoid sinus is 35+ mm anterior to this plane. Separates from M. stejnegeri.

Occurs in tropical to temperate waters of the Atlantic, Pacific and Indian Oceans. Mesoplodon densirostris has the widest distribution of any Mesoplodon species.

Tooth position A single pair of teeth are positioned at the top of the anterior edge of the jaw arch. The teeth incline forward at a 45 degree angle. Tooth exposure Erupted teeth in adult males are massive, but largely covered by gum tissue with only the tip of tooth exposed. Teeth do not erupt in females or juveniles. Tooth shape The anterior tooth margin is sinusoidal, convex proximally and concave distally. The posterior margin is convex. There is a strong terminal denticle.