Phylum Chordata, Subphylum Vertebrata, Superclass Gnathostomata, Class Reptilia, Subclass Diapsida Order Testudines Superorder Lepidosauria Order Sphenodonta

Phylum Chordata, Subphylum Vertebrata, Superclass Gnathostomata, Class Reptilia, Subclass Diapsida Clade Archosauria – ruling lizard

Crocodile Heart Bird Heart

Phylum Chordata, Subphylum Vertebrata, Superclass Gnathostomata, Class Reptilia, Subclass Diapsida Superorder Archosauria Order Crocodilia

Phylum Chordata, Subphylum Vertebrata, Superclass Gnathostomata, Class Aves, Subclass Neornithes

Craniata (euchordates with a cranium) = Vertebrata Gnathostomata (Craniata with jaws) Osteichthyes (bony fishes + tetrapods) Tetrapoda (four-limbed vertebrates) Amniota (tetrapods with embryos having extraembryonic membranes) Reptilia ProtochordataAgnatha Urochordata (tunicates) Cephalaspidomorphi (lampreys) Actinopterygii (ray-finned fishes) Actinistia Amphibia Mammalia (mammals) Lepidosauria (lizards, snakes) Testudines (turtles) Crocodilia Aves (birds) Cephalochordata (lancelets) Myxini (hagfishes) Chondrichthyes (sharks, rays, chimaeras) Slime glands, accessory hearts Suckerlike oral disc, long larval stage, 7 pairs of gills Heterocercal caudal fin, placoid scales, cartilaginous skeleton Hair, mammary glands Notochord, dorsal hollow nerve cord, pharyngeal slits, postanal tail, endostyle Neural crest Distinct head and tripartite brain, skull, paired specialized sense organs, vertebrae Jaws, pelvic and pectoral girdles, calcified teeth, gill filaments lateral to gill support Lung or swimbladder derived from gut, bony endoskeleton Paired appendages with long muscular lobes, unique supportive elements in skeleton or girdles of appendages, pulmonary vein Four pentadactylous limbs, stapes, atlas (1 st cervical vertebra) Egg with extraembryonic membranes, keratinized skin, axis (2 nd cervical vertebra), aspiration pump Skull with upper and lower temporal fenestra, Beta-keratin in epidermis Dipnoi Sarcopterygii (lobe-finned) Pulmonary circulation, two chambered atrium Chordata (animals with notochord at some stage in life cycle)

Class Mammalia

Phylum Chordata, Subphylum Vertebrata, Superclass Gnathostomata, Class Mammalia

Rommel and Reynolds, 2000

Marine Mammals

Cetaceans Pinnipeds Sirenians Polar bear Sea otter

Order Artiodactyla Suborder Cetacea Order Carnivora Suborder Pinnipedia Order Sirenia Family Ursidae Family Mustelidae

What’s the big deal about being an aquatic mammal?

Problem and Solutions Problem: Heat conductivity of water 25x that of air Solutions?

Solutions  Insulation Marine mammals - two forms of insulation FurBlubber

INSULATION THICKNESS (mm) INSULATION (W -1 M 2o C) Still AirDry Fur Wood Adipose Muscle Water Copper Sea otter hair, Wet Harbor porpoise blubber Spotted dolphin blubber

INSULATION THICKNESS (mm) INSULATION (W -1 M 2o C Still AirDry Fur Wood Adipose Muscle Water Copper Polar bear hair, Dry Polar bear hair, Wet

Thermal Windows Feet Flippers Dorsal fin Pectoral flippers Tailflukes

Rommel et al., ‘98

Countercurrent exchanger

Conclusions Marine mammal solutions Insulation - fur and blubber Vasculature

Thermal Problem for Male Reproductive Systems Problem: Sperm production requires lower temp Terrestrial mammal solution Scrotum or cremaster sacs

Rommel et al., ‘98

The Cetacean Solution Rommel et al., ‘92

Rommel et al., ‘98

Structure without function is a corpse; function sans structure is a ghost - Vogel and Wainwright, ‘69