BIO358 1st Edition Lecture 8 Outline of Last Lecture I What is challenging about living in water A Imagine yourself in the ocean B Physical properties of water C Heat conductivity coefficient II Solutions to living in water A Structure of the integument B Fur Density fur seals and otters C Blubber cetaceans and other otariids D What about polar bears Outline of Current Lecture I Review II How do marine mammals dissipate body heat A Counter current heat exchange III Enhanced sensory systems A Echolocation biosonar Current Lecture Large body size large SA V ration Large volume of tissue generating heat relative to the amount of surface area exposed to the environment Insulative material of integument are important to reducing heat loss Epidermal solution of fur and the hypodermal solution of blubber Fur seal and otters use fur Everyone else EXCEPT for the polar bear use blubber These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute Thick integument formed by blubber or fur to insulate the large body against heat loss Dissipate body heat i e vacation in the tropics out in air very insulated needs to dissipate heat i e Dolphin or blue whale going for a hard fast swim need to dissipate body heat to dissipate excess body heat marine mammals must be able to by pass their insulation THIS REQUIRES NON INSULATED SURFACES CALLED THERMAL WINDOWS Visualize 5 k run on a day in august in Wilmington You turn red because you are shunting blood to the surface of your body How are animals not constantly dumping heat through thermal windows They need to be able to turn on or off dynamic Thermal Windows requirements 1 uninsulated no fur no blubber 2 large flat plate shaped structures relatively large SA 3 specialized vascular structures including superficial veins to dissipate heat 4 Deep counter current heat exchangers using deep veins and central arteries to conserves heat Steps of cooling 1 Arteriole blood travels too the thermal window 2 Warm blood shunted to the surface of the thermal window 3 heat is lost to the environment across the surface of the thermal window 4 cooled blood is carried back to the body via superficial veins Thermal windows must be dynamic turn on and off blood flow is changing Counter Current Heat Exchanger CCHE 1 pipes that are juxtaposed 2 the flow of fluid in those pipes is in the opposite direction i e counter current flow 3 temperature differential between the fluid flowing through the pipes arteries carry warm blood to the thermal window veins are carrying cool blood from the thermal window Transfer of heat to the veins to conserve body heat Bottlenose dolphin dorsal fin Central arteries go into the dorsal fin Cross section regularly placed central arteries brings warm blood to the fin Superficial veins closer to surface Separate set of veins rosettes completely surrounding each central artery counter current heat exchanger Conductance C is dynamic dependent upon blood flow to thermal windowns and body surfaces Review Characteristics of large mammals Large body size Streamlined body Reduced appendages Enhanced insulation Enhanced diving Enhanced sensory system SENSORY SYSTEMS Vision important sensory modality for most terrestrial mammals BUT light doesn t transmit well through water Light energy is attenuated drastically in water compared to in air Functional problem vision is not as functional at depth and with turbidity Functional solution use another sense hearing Water transmits sound much more effectively than air Low frequency sound is attenuated 6 million times faster in dry air than in water So sound is good to use in water Odontocete echolocation AKA biosonar sonar SOundNAvigaiton and Ranging Sound is a wave that is created by vibrating bodies and propagated through a medium air water solid from one location to another A wave is a disturbance that travels through a medium transferring energy from one medium to another Talking vibrating pressure wave transferred to ears transduced to neuro signal Visualize pressure with pressure and time as a sinusoidal wave Peak compression Valley expansion Amplitude Height of wave loudness of sound Measured on a decibel scale which is a log scale dB 20 log pm pr pm measured pressure pr reference pressure 1 uPascal in water 100 fold increase Quiet whisper 30 decibels Hearing loss 90 95 Concerts 150 Log scale so these differences are much larger than they seem Frequency number of pressure waves per unit time measured in Hertz cycles second Biosonar sounds so high you cant hear them ultrasonic 50 130 kHz this means something in the head of a bottlenose dolphin is vibrating very fast Ken Norris put little blind folds on dolphins suction cups Discrimination tasks dolphins could do this with the blindfolds Dropped a hydrophone in the water when the animal was making these discriminations Ken Norris helped recreate the field of marine mammal biology Biosonar system 1 A receiving system a Auditory system ear lower jaw pan fat 2 Transmitting system a Monkey lips dorsal bursae MLDB nasal system melon 3 Signal processing system a Acoustic nerve and CNS Receiving system human Pinnae funnel sound into the human external ear canal that ends in the ear drum 3 oscicles in the middle ear move and the oval window sets up fluid filled channels in the inner ear External middle and inner ear Bottlenose hearing Tiny hole behind the eye lacking pinnae middle ear specialized bulla with middle ear ossicles also called tympanic bulla Jaw has a pan thin caudal end of the mandible close proximity to bulla expanded pan of bone is filled with fat