Senses Sperm whale

anatomy of sperm whale s head. organs above jaw devoted sound generation.

atop whale s skull positioned large complex of organs filled liquid mixture of fats , waxes called spermaceti. purpose of complex generate powerful , focused clicking sounds, sperm whale uses echolocation , communication.

the spermaceti organ large barrel of spermaceti. surrounding wall, known case, extremely tough , fibrous. case can hold within 1,900 litres of spermaceti. proportionately larger in males. oil mixture of triglycerides , wax esters. proportion of wax esters in spermaceti organ increases age of whale: 38–51% in calves, 58–87% in adult females, , 71–94% in adult males. spermaceti @ core of organ has higher wax content outer areas. speed of sound in spermaceti 2,684 m/s (at 40 khz, 36 °c), making twice fast in oil in dolphin s melon.

below spermaceti organ lies junk consists of compartments of spermaceti separated cartilage. analogous melon found in other toothed whales. structure of junk redistributes physical stress across skull , may have evolved protect head during ramming.

running through head 2 air passages. left passage runs alongside spermaceti organ , goes directly blowhole, whilst right passage runs underneath spermaceti organ , passes air through pair of phonic lips , distal sac @ front of nose. distal sac connected blowhole , terminus of left passage. when whale submerged, can close blowhole, , air passes through phonic lips can circulate lungs. sperm whale, unlike other odontocetes, has 1 pair of phonic lips, whereas other toothed whales have two, , located @ front of nose instead of behind melon.

at posterior end of spermaceti complex frontal sac, covers concave surface of cranium. posterior wall of frontal sac covered fluid–filled knobs, 4–13 mm in diameter , separated narrow grooves. anterior wall smooth. knobbly surface reflects sound waves come through spermaceti organ phonic lips. grooves between knobs trap film of air consistent whatever orientation or depth of whale, making excellent sound mirror.

the spermaceti organs may adjust whale s buoyancy. hypothesized before whale dives, cold water enters organ, , blood vessels constrict, reducing blood flow, and, hence, temperature. wax therefore solidifies , reduces in volume. increase in specific density generates down force of 392 newtons (88 lbf) , allows whale dive less effort. during hunt, oxygen consumption, blood vessel dilation, produces heat , melts spermaceti, increasing buoyancy , enabling easy surfacing. however, more recent work has found many problems theory including lack of anatomical structures actual heat exchange.

herman melville s fictional story moby dick suggests case containing spermaceti serves battering ram use in fights between males. few famous instances include well-documented sinking of ships essex , ann alexander attackers estimated weigh one-fifth as ships.

eyes , vision


like other toothed whales, sperm whale can retract eyes.

the sperm whale s eye not differ of other toothed whales except in size. largest among toothed whales, weighing 170 g. overall ellipsoid in shape, compressed along visual axis, measuring 7×7×3 cm. cornea elliptical , lens spherical. sclera hard , thick, 1 cm anteriorly , 3 cm posteriorly. there no ciliary muscles. choroid thick , contains fibrous tapetum lucidum. other toothed whales, sperm whale can retract , protrude eyes 2-cm-thick retractor muscle attached around eye @ equator.

according fristrup , harbison (2002),

sperm whales eyes afford vision , sensitivity light. conjectured sperm whales use vision hunt squid, either detecting silhouettes below or detecting bioluminescence. if sperm whales detect silhouettes, fristrup , harbison suggested hunt upside down, allowing them use forward parts of ventral visual fields binocular vision.