Anatomy Pygmy sperm whale

1 anatomy

1.1 teeth
1.2 melon
1.3 stomach
1.4 brain

anatomy

like giant relative, sperm whale, pygmy sperm whale has spermaceti organ in forehead (see sperm whale discussion of purpose). has sac in intestines contains dark red fluid. whale may expel fluid when frightened, perhaps confuse , disorient predators.

pygmy sperm whales have 50 55 vertebrae, , 12 14 ribs on either side, although latter not symmetrical, , hindmost ribs not connect vertebral column. each of flippers has 7 carpals, , variable number of phalanges in digits, reportedly ranging 2 in first digit many 10 in second digit. no true innominate bone exists; replaced sheet of dense connective tissue. hyoid bone unusually large, , presumably has role in whale s suction feeding.

skull


teeth

the pygmy sperm has between 20 , 32 teeth, of set rostral part of lower jaw. unusually, adults lack enamel due mutation in enamelysin gene, although enamel present in young individuals.

pygmy whale teeth on lower rostrum


melon

like other toothed whales, pygmy sperm whale has melon , body of fat , wax in head uses focus , modulate sounds makes. inner core of melon has higher wax content outer cortex. inner core transmits sound more outer layer, allowing refract sound highly directional beam. behind melon, separated thin membrane, spermaceti organ. both melon , spermaceti organ encased in thick fibrous coat, resembling bursa. whale produces sound moving air through right nasal cavity, includes valvular structure, or museau de singe, thickened vocal reed, functioning vocal cords of humans.

note view pictured on right axial view, not coronal noted

stomach

the stomach has 3 chambers. first chamber, or forestomach, not glandular, , opens directly second, fundic chamber, lined digestive glands. narrow tube runs second third, or pyloric, stomach, glandular, , connects, via sphincter, duodenum. although fermentation of food material apparently occurs in small intestine, no caecum present.

brain

the rostroventral dura of brain contains significant concentration of magnetite crystals, suggests k. breviceps can navigate magnetoreception.