BIO358 1st Edition Lecture 10 Outline of Last Lecture I Review II Receiving system of biosonar A Odontocete lower jaw B Bullock et al 1968 C Brill et al 1988 III Transmitting System of biosonar A Cranford 1996 B Melon C Harper et al 2008 Outline of Current Lecture I Requirements of feeding in water II Pinniped feeding III Mysticete feeding Current Lecture Feeding in marine mammals To successfully forage underwater you need to find and localize prey specialized sensory systems acquire prey locomotor and digestive systems MOUTH Odontocete echolocation AKA Biosonar Mysticetes we do not have a good idea of how they find their prey 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 Sensory hairs on surface of snout and jaw rostrum called vibrissae Hard to find answers to these questions Pinnipeds Vision Vibrissae tactile sense beautiful whiskers tactile acuity like our hands Thermoregulatory cost associated with vibrissae Erdsack et al 2014 o Hot spots eyes and whiskers o Blood sinus surrounds base of whiskers each whisker has blood supply of a certain temperature to be able to feel o Eyes are also maintained at a high temperature Acquiring prey integrate locomotor system with your mouth Suction feeding usually requires a sudden change in shape of oral cavity common fish eating technique Increase the volume of oral cavity internal pressure decreases which sucks water and whatever prey might be in that water into the oral cavity Ram feeding using locomotor system to overcome the prey and grab the prey similar to terrestrial predation Most pinnipeds are RAM Feeders Most otariids and phocids have sharp pointy teeth to pierce fish and cephalopods Teeth used to grab prey whole and swallow food whole no mastication chewing Crabeater seal Lobodon carcinophagus Eats krill Lobodon lobed structure of teeth Cheek teeth of lobodoncarcinophagus lobe shaped act as a sieve o Suck in large volume of water with krill strain water out through lobed cheek teeth that sort out krill o Suction feeder Crabeater vs leopard seal teeth Leopard seal voracious predator of other endotherms eats whatever it wants Has the same cheek teeth as the crab eater seal they can also feed on abundant Antarctic krill taking advantage of the base of the food chain Odobenidae feeding Benthic feeders bivalves preferred prey Use sensitive vibrissae snout and fore flippers to find and localize prey within the sediments Razor clams Once they have found the clams they suck in water and create a jet of water to dislodge the clams from the sediment Or they will just suck the clams in whole with the sediment 6000 clams per daily meal open clams by sucking the clams out can handle 6 7 clams a minute spend a large portion of their life with their head buried in the sediment bioturbation disturb the sediments important in benthic arctic communities new open spaces for other animals to colonize Build a successional path for vertebrates in the sediments Global Climate Change sea ice loss conservation threat context of feeding biology walruses feed on clams and invertebrates rest between feeding trips on ice ice access to offshore feeding locations and isolation from humans ice transports walruses over wide feeding ranges adult females and young animals stay on ice even in the summer walruses do not go deep for their food map water depth and land bodies shallower water by continental shelf sea ice has been historically maintained out by shallow water by the continental shelf TODAY that ice out over deep waters More and more odobenids are hauling out on land because they need shallower waters to forage Ice loss forces animals onto land increased density increased mortality skiddish animals charges kills young animals Females travel farther for food calf mortality Sea ice loss profound negative impact on polar species that rely on access to ice for their prey Ie Polar bears eat ring seals ring seals need ice to protect young Cetaceans feeding General Huge range of prey size Copepods pinnipeds orcas kill whales larger than themselves Mysticetes eat smaller prey Mysticetes Blaenids skim feeders Skim out small prey with very fine filter Longest baline 3 4 meters Many plates 350 plates side Fine baline like our hair Neobalaenidae Blaenopterids gulp feeder Echrictiids bottom suction feeder 5 m plates coarse hairs 155 plates side Balaenids shape bow head big and stocky LOTS of Blubber slow simmer right whale to hunt swims slowly at the surface or at depth with mouth open o Captures in tiny copepod prey o Prey move into the mouth go in on their own Probably not not suction or ram feeding but water and prey enter the mouth 1780 fabricious o How does this work Really big bulky object moving through the water usually push a bow wave in front of them that pushes away anything in their path Why are copepods going into the mouth instead of being pushed away Graduate student Alex Werth 2004 went to bowhead whale hunt and got access to the head of an animal and made measurements and models of the head in an open postion Pressure transducers all around head model and measured pressures with a flow in a flow tank Discovered that the shape of the head and oral cavity creates a pressure gradient that sucks water into the mouth Water comes into the big opening at the front of the mouth slow speed water escapes out of the mouth in smaller openings in the back of the opening faster speed differential flow velocities narrow pipes faster flows wider pipes slower flow Inverse relationship between speed of fluid flow and pressure Fluid flow slow pressure flow high Fluid flow fast pressure flow low CONTINUITY OF MASS How does fluid flow High pressure to low pressure shape of mouth allows water to flow from an area of high pressure to low pressure and water is sucked into the oral cavity Hybrid between ram and suction feeding from morphology of the mouth Balaenopterids Body shape hydrodynamic low drag fast swimmers Ram suction feeding hybrid different than balaenids Swim at high speeds to prey patch and open up mouth suddenly and engulf huge amounts of water and prey dramatic change in body shape Specialize ventral groove blubber rorquals 70 80 ventral grooves open up like an accordion 70 tones of water in an adult blue whale water weights more than the whale weighs Muscles hold ventral groove blubber and are contracted holding it in during swimming When the animal