5. Anatomy_FA2023 (1).pdf

MARI 3090 – Marine Mammalogy Dalhousie University Dr. Amanda Babin Fall 2023 Rommel and Fernandez 2006 Anatomy External Anatomy Missing in some species (toothed-1, baleen-2) aka rostrum vibrissae nipples • Streamlined bodies reduce drag Cetacean Blowholes whaleanddolphintrust.co.uk • •...

MARI 3090 – Marine Mammalogy Dalhousie University Dr. Amanda Babin Fall 2023 Rommel and Fernandez 2006 Anatomy External Anatomy Missing in some species (toothed-1, baleen-2) aka rostrum vibrissae nipples • Streamlined bodies reduce drag Cetacean Blowholes whaleanddolphintrust.co.uk • • • • Homologous to nostrils One in Odontocetes, two in Mysticetes The blow is warm air with water vapor that condenses in the colder sea air Trachea (to lungs) and esophagus (to stomach) are designed such that they do not choke on food, or breathe with mouth Cetacean Dorsal Fins • Used for stability and thermoregulation • Stability allows for greater speed • Cartilage-only Pimkie wdcs.org polarbearalley.com capetown-enchantingcity.com Cetacean Flukes Blue • • • • Fin No bones in fluke Very muscular, tendons dictate shape Width proportional to body length Remnants of hindlimbs are independent Humpback Orca wikipedia.org Forelimb comparison Encyclopedia of Marine Mammals projectminke.com Cetacean Pectoral Flippers Minke Humpback Right Orca Blue seaworld.com Pinniped Forelimbs Phocid (harbour seal) Otariid (Australian Fur seal) Walrus NWF seaworld.com Pinniped Hindlimbs Phocid (harbour seal) Otariid (Galapagos Sea Lion) Walrus DFO thewhaletrail.org wild-scotland.org.uk Pinniped Nares Harbour seal – V Grey seal – W asknature.org Elephant Seal Internal Anatomy Furado marshallcavendish Blubber • Blubber is made of fibrous connective tissue, interspersed with oilfilled cells birds.cornell.edu schoolnet.org.za • Provides warmth, energy storage, and buoyancy • 12-50 cm thick Muktuk Muscles • Fluke muscles are the strongest in the body • Penis is prehensile and can be extended/retracted • Diaphragm reinforced with collagen to withstand pressurea aMargo Lillie SMM2017 marshallcavendish Baleen/Tongue wikimedia.com studydroid.com • Tongue used for thermoregulation • Scrapes copepods/krill off of baleen Oral plug • Found in fin whales, likely to be all rorquals • Soft palate attached to the vomer (bone that separates the left and right nasal cavities) • Down when breathing • Up when feeding Odontocete Melons • Fat tissue (not metabolized) • Matches acoustic impedance of water • Focus sound beam (acts as lens) • Determines direction • Belugas can change the shape at will tolweb.org Sperm whale head Reproduced with permission from Catherine Hood • Spermaceti and Junk • Colder and higher pressure = higher density • Neutrally buoyant at 200 m Cetacean Stomach • 3 chambers • Fore stomach does mechanical breakdown • Main stomach does chemical breakdown (HCl and enzymes) • Pyloric stomach has more enzymes and an alkaline fluid which neutralizes the HCl marshallcavendish Pinniped Stomach • Very similar to terrestrial mammal carnivore stomach Heart aMargo Lillie SMM2017 bJacqueline Miller SMM2017 Royal Ontario Museum • Arteries stiffened to withstand pressurea • In 2014, 9 blue whales got stuck in ice in the Gulf of St. Lawrenceb • Aortic bulb 37 cm diameter • Only 0.22-0.26% of body mass Seal sleeping → • Magnetite crystals (iron oxide) act like a magnetic compass • Sleep with half their brain at a time (unihemispheric) • Some odontocete brains have grey matter that is more convoluted than humans (more gyrified) • Encephalization quotient (EQ): • 7 in humans • 3-5 for some delphinids • 2-3 for other primates delphinusblog.wordpress.com Brain Other Organs Human Organs Thyroid Pancreas Spleen Gall bladder Appendix Whales Yes Yes Yes No No Seals Yes Yes Yes Yes No • Three main functions: • Support the body • Protect the organs • Provide muscle attachment for locomotion • Light skeleton: 17% of body mass • 45% spinal column, 45% skull and jaw, 10% pectoral flippers, etc. • Filled with marrow of high oil content • When stranded, some whales may be crushed by their own weight Reproduced with permission from Catherine Hood Cetacean Skeleton Skull • Symmetical in mysticetes, asymmetrical in odontocetes nhc.ed.ac.uk Orca ancientshore.com Minke Whale Californian Sea Lion Right Whale Hyoid Bone capelookoutstudies.org • Attachment point for muscles • Helps move jaw, floor of mouth, tongue, and larynx • Muscles connect to the tip of the jaw and rib cage so they can dip their head to aid locomotion Cervical Vertebrae • Compacted/fused in many cetaceans to prevent injury Reproduced with permission from Catherine Hood Ribs pugetsound.edu • Flexible to allow for collapsing of ribs and lungs Chevron Bones cetacea.ca • Extra attachment points for fluke muscles • Protects blood vessels Take Home Messages • Fin shapes • Odontocete melons match the acoustic impedance of water • Cetaceans have 3 stomach chambers • Fore, main, and pyloric • Pinnipeds and other carnivores have one-chambered stomachs • Delphinids have higher EQs than non-human primates • Cetacean bones are light, porous and full of oil • no bones in fluke • cervical vertebrae often fused Thank you! mnh.si.edu