Marine Mammals Oceanography

 Marine mammals are some of the world’s most spectacular animals  They include the largest animals that have ever lived  Their social behaviors and intelligence surpass much of what we know about most creatures Things to Note:

 Eukaryotes Classification of Marine Mammals Animalia – Animal Kingdom Mammalia Chordata – Vertebrates (have a backbone) CetaceaPinnipediaSirenia Whales, Dolphins, Porpoise Seals & Sea lions Dugongs & Manatees

 All organisms in the class Mammalia share these characteristics:  They have hair on some part of their body  They nourish their young with milk provided by mammary glands  They are homeothermic (warm blooded) with a constant internal temperature  The majority give birth to live young Characteristics of Marine Mammals

 Scientists think that mammals have evolved on land, and that marine mammals evolved from land mammals that returned to the sea.  Challenge 1: life in water demands high oxygen consumption  Adaptation – Marine mammals breathe air (they do not extract dissolved oxygen from water like normal fish) Marine Mammals – Challenges & Adaptations

 Challenge 2: Marine mammals cannot exist chained to the surface of the ocean because of their need to breathe air  Adaptations:  1. Myoglobin: allows marine mammals to store much more oxygen in their bodies than terrestrial mammals  2. Mammalian diving reflex: when marine mammals dive to deep depths their pulse rate slows and blood flow diverts lowering the rate of oxygen use (which extends the time they have until they need to “breathe” again) Marine Mammals – Challenges and Adaptations

 Challenge 3: Water pressure  Adaptations:  Marine mammals have flexible lungs and sinuses allowing them to compress without pain or injury  Dolphins and whales have lungs that engorge with blood, offsetting the compressed space Marine Mammals – Challenges and Adaptations

 Challenge 4: Movement through water (water is more dense than air)  Adaptations:  Streamlining & Hydrodynamics  Skin is elastic and responsive to its surroundings  Skin constantly loses cells acting like a lubricant that minimizes water drag Marine Mammals – Challenges and Adaptations

 Challenge 5: Senses – Terrestrial mammals use sight, smell and hearing as their primary senses; water reduces the ability to see and smell  Adaptations:  1. Echolocation  2. Sensitive hearing Marine Mammals – Challenges and Adaptations

 Seals, Sea lions, Walrus  Classified into different families based on certain physiological characteristics Order: Pinnipedia

 “True seals”  No ear flaps  Rear flippers point backward (cannot rotate forward)  This is why seals look like they crawl on their stomach when getting out of water Seals

 Fur “seals”  Have ear flaps  Hind flippers can rotate underneath them, giving them more mobility out of water  Can sit more fully upright Sea lions

 Third family; between seals and sea lions  No ear flaps (like a seal)  Can rotate its hind flippers forward (like a sea lion) Walrus

 Dolphins, Whales, & Porpoises  Show the most adaptation to living in the sea  Scientists believe their ancestors were the first to return to the sea  Fish-like bodies; breathe air through a blowhole on top of their head  No hind limbs  Huge, muscular tails  Almost no hair; thick layers of fat (blubber) Order: Cetacea

 Filter feeders  Baleen: brush like fringe that hangs from the roof of a whales mouth  Baleen whales take in mouthfuls of water and then releases the water through the baleen while trapping plankton, krill, and small fish  Examples: Humpback whale, gray whale, blue whale Suborder: Mysticeti (Baleen Whales)

 Predators  Use echolocation to communicate for hunting purposes  Example: Sperm whale (noted for feeding on the giant squid), orca, dolphins, porpoise Suborder: Odontoceti (Toothed Whales)

 Dugongs and Manatees (sea cows)  Only 4 species – rare and endangered!  Relatives of the elephant  Herbivores Order: Sirenia

 Whaling – main reason many whale species began to reach the verge of extinction at the end of the 19 th century  Banned/Severely limited by international convention Marine Mammals and YOU!

 Many people hunt seals for their fur and manatees for their meat.  Illegal in most countries now  More recent concerns: Dolphins killed accidentally as a result from tuna fishing Marine Mammals and YOU!

 Loss of food due to overfishing or pollution is a potential threat that scientists and environmentalists must now watch closely! Marine Mammals and YOU!