Transcript Document
Marine Mammals Marine Mammals “... Hmmm...Bottlenosed Bruises, Blowhole Burns, flipper prints, This looks like the work of rowdy teens, Lou cancel the prom ... .” – Chief Wiggum What are marine mammals? Mammals that live and feed in the marine (aquatic) environment What are Mammals? Mammary glands – nurse young with milk Hair Diaphragm Are Cetaceans Mammals? Class Mammalia Order Carnivora Polar bears, sea otters, seals, sea lions, walruses Order Sirenia “Sea Cows” Manatees, dugongs Order Cetacea Baleen whales, toothed whales (e.g. sperm whale, dolphin, beluga, porpoise) Polar Bear, Polar Bear, What Do You Hear? Order: Carnivora Suborder: Fissipedia (cleft foot) Family: Ursidae (Polar bear) Better viewed as a wateradapted terrestrial mammal Sustained swimmers Hollow (transparent) hair fibers too buoyant for diving Sea Otters! Order: Carnivora Suborder: Fissipedia (cleft foot) Family: Mustelidae (Sea otter) - Keystone predator in kelp ecosystems - Feed on urchins & abalone - Fur for thermoregulation – 150,000 hairs/cm2 - Near TNZ – rely upon “heat increment of feeding” - eat > 25% of body wt / day Suborder Pinnipedia “feather-footed” – 3 families 34-36 species – (25% of marine mammals) Phocidae – (true seals)19 spp. Otariidae – (sea lions, fur seals) 14-16 spp. Odobenidae – (walrus) 1 sp. Seal or Sea Lion??? e.g. Steller sea lion, California sea lion, Galapagos fur seal, Northern fur seal, e.g. Harp seal, Northern elephant seal, Hawaiian monk seal Hawaiian Monk Seals 3 Monk seal species (Caribbean & Mediterranean) All critically endangered (H & M) or thought to be extinct (C) Most primitive phocids More sensitive to human intrusion than other seals Population numbers are low (<1,500) and are decreasing due to: - death from predation by sharks - lower pup survival as the result of human disturbances - ciguatera intoxication - entanglement in fishing nets and debris - “mobbing” behavior - genetic bottlenecking – reduction in allele frequency (genepool) due to low number of individuals - disease Order Sirenia “Sea Cows” Tropical/subtropical in shallow water Less sophisticated social behaviors than cetaceans Less specialization for aquatic existence Family Trichechidae Manatee (3 spp) Family Dugongidae Dugong (1 sp) All endangered Order Cetacea “All he does is lie there like an unemployed whale.” – Bart Simpson 2 Suborders: Mysticeti – baleen whales (12-14 species) blue, humpback, grey whales Odontoceti – toothed whales, dolphins, porpoises (≈ 75 species) Earliest recorded marine mammals Most diverse & adapted - marine existence Order Cetacea “Oh, who thought a whale could be so heavy?! Cheese it! The feds!” – Moe Syzlak Mysticeti: Loss of teeth (except in embryonic stages) 2 blowholes; symmetric skull Development of large body size & heads Shortening on intertemporal region & neck Odontoceti: Presence of teeth in adults Telescoping of rostrum; Presence of melon Single blowhole; Skull & soft-tissue asymmetry Order Cetacea “Oh, who thought a whale could be so heavy?! Cheese it! The feds!” – Moe Syzlak Mysticeti: Loss of teeth (except in embryonic stages) 2 blowholes; symmetric skull Development of large body size & heads Shortening on intertemporal region & neck Odontoceti: Presence of teeth in adults Telescoping of rostrum; Presence of melon Single blowhole; Skull & soft-tissue asymmetry Order Cetacea Mysticete Odontocete Mysticetes “They like you very much, but they are not the hell your whales.” – Mr. Spock Class: Mammalia Order: Cetacea Suborder: Mysticeti Family: Balaenidae (3 species – N. & S. right whales (Eubalaena), bowhead (Balaena) Family: Neobalaenidae (pygmy right whale) Family: Balaenopteridae (blue, fin, sei, Bryde’s, minke, humpback) Family: Eschrichtiidae (gray whale) Suborder Odontoceti “You know its the largest mammal on earth but as George says ‘they don't have to be’.” – Jerry Seinfeld Sperm whale (1) Pygmy/dwarf Sperm whales (2) (1) Ganges River Dolphin (21) Beaked Whales (1) Baiji River Dolphin (1) Bouto River Dolphin (1) Franciscana R. Dol. (2) Narwhal/Beluga Oceanic Dolphins (36) (6) Porpoises Porpoise vs. Dolphin “Oooh. You're not sharks. You're dolphins. The clowns of the sea”. – Lenny Leonard Marine Mammals Adaptations to an Aquatic Existence Insulated skin – blubber or dense fur Countercurrent heat exchange systems Eyes, nose, ears – terrestrial, FW, SW High Frequency sounds Adaptations to an Aquatic Existence Insulated skin – blubber or dense fur Insulative value a function of thickness, lipid content, & peripheral blood flow Skin Skin Blubber Blubber Muscle Blubber Muscle Muscle Cetacean/Pinniped Manatee Counter Current Heat Exchangers Heat is conserved before it is lost at the extremity Parallel intermingling vessels = vascular bundles (rete) 39°C 37°C 35°C 33°C 31°C 29°C 27°C 28°C 38°C 36°C 34°C 32°C 30°C Veins Artery Adaptations to an Aquatic Existence Modified limbs – fore & hind limbs, tail Bowhead Whale Sea Lion Manatee Flippers & Locomotion In cetaceans, pinnipeds, sirenians – forelimb proportions altered Pectoral fin is forearm & hand – elbow not external Also seen in marine reptiles, ichthyosaurs, mosasuars Pilot Whale Blue Whale Right Whale Marine Mammals Relating Evolutionary Events