Marine Mammals Order Cetacea

1. Marine MammalsOrder Cetacea Tamisha Michalewicz

2. Order Cetacea Archaeoceti www.seaworld.org/.../KillerWhale/sciclasskw.html • Two suborders • Mysticeti (Baleen Whales) • Odontoceti (Toothed Whales) • One extinct suborder • Archaeoceti (Ancient Whales) • Live, Breed, Rest, and carry out all of their life functions in the water

3. Cont. • Inhabit all of the world’s oceans • As well as, some freshwater lakes, rivers, brackish waters of estuaries and coastal marshes

4. Mysticeti • Most of the largest Cetaceans • i.e. Blue Whales (Balaenoptera musculus) which are the largest animal in history • Exceeding 100 feet and weigh as much as 160 tons • Smallest is the pygmy right whale (Caperea marginata) • Measure up to 23 feet • More examples: humpback whale (Megaptera novaeangliae), fin whale (Balaenoptera physalus), and southern right whale (Eubalaena australis) www.nefsc.noaa.gov/.../beached_blue_whalebb.jpg

5. Humpback Whale – Megaptera novaeangliae cas.bellarmine.edu/tietjen/RootWeb/Chiroptera.jpg Fin Whale - Balaenoptera physalus www.exzooberance.com/virtual%20zoo/they%20swi

6. Odontoceti • Largest and most diverse group • i.e. the sperm whale is the largest • Reaching about 60 feet • The largest living predator of warm-blooded animals is the killer whale • More examples: Dolphins and porpoises Sperm Whale – Physeteridae animals.nationalgeographic.com/staticfiles/NG...

7. Bottle Nose Dolphin – Tursiops trucatus www.naturescornermagazine.com/NaturesBlog/ima... Harbor Porpoise - Phocoena phocoena animals.nationalgeographic.com/staticfiles/NG

8. Taxonomic History • Hippopotamids are closest living relatives • Followed by ruminants • i.e. cows • Followed by Artiodactyls www.redmills.ie/images/ruminants.jpg cas.bellarmine.edu/.../RootWeb/Artiodactyla.jpg www.cbc.ca/gfx/photos/hippo_cp_5128012.jpg

9. How do Cetaceans reduce drag for fast swimming? • Fusiform body • Tapered at both ends • Paddle-shaped front limbs • No external digits or claws • Tail flattened laterally and bearing horizontal flukes at the tip • Vestigial ear pinnae • Hairless body • Thick subcutaneous blubber layer filled with fat and oil

10. Cont. • Addition of compressed vertebrae • Shortening of the neck • Lack of sweat glands • Internal reproductive organs • Three chambered stomach • Telescoped skull bones • External nares on top of head • Odontoceti have one blow hole • Mysticeti have two blow holes upload.wikimedia.org/.../300px-Cetacea.jpg

11. Coping with Cold Climates • Small cetaceans • Have high metabolic rates • Flippers and flukes have a countercurrent heat exchange system • Heat from arterial blood warms venous blood as it returns to the heart • Large cetaceans • Small surface to volume ration • Lose little heat to the surrounding environment • Both are insulated by thick blubber layer www.cresli.org/.../2003_WW/breacher_fluke.jpg

12. Physiological Adaptations for Deep Diving • Rapid exchange in lungs • Enhanced by double capillary layer in the intraalveolar septae • Humans use 4% of Oxygen inhaled, Cetacea use 12% • Twice the number of erythrocytes and myglobin molecules in their blood • Allows for efficient capture and transport of oxygen

13. Cont. • Alter blood distribution • Rate of flow slows down (Undergo bradycardia) • Heart rate slows by as much as 80 beats per minute • Eliminated at non-critical organs via shunts • i.e. digestive tract • Reserved for critical tissues • i.e. heart and brain • High tolerance to Carbon Dioxide and lactic acid build up in tissue

14. Physiological Problems with Deep Diving • Increased pressure with increased depth • At high pressure gases go into solution more quickly • Air breathing organisms have a problem with Nitrogen gas absorption into blood • Causes decompression sickness • i.e. Bends or Caisson’s Disease

15. Physiological Solutions to Deep Diving • Structural Adaptations • Lungs are small • The total amount you take in = the total amount you let out • Dead air spaces are large • i.e. trachea and nasal cavity • Trachea is large and supported by cartilaginous rings • Bronchioles are small but braced by muscles and cartilaginous rings down to alveoli • Ribs are free from sternum Sperm Whale – Physeteridae www.nwf.org/nationalwildlife/article.cfm

16. Cont. • Mechanism • Total exhalation before diving • Diving pressure forces collapse of lungs • Forces air into dead air spaces, including nasal passages • Dead air spaces devoid of vascular tissue • Nitrogen is six times more soluble in oils then in water • Blubber is highly vascular and serves as Nitrogen reservoir • Oil also present in nasal sinus and may absorb nitrogen there as well gimp-savvy.com.

17. Mating • Usually have one mating season per year • Gestation is about 10 to 17 months • Females give birth to a single calf every one to six years • Calves are born tail first and must swim from the moment of birth • Mysticetes nurse for about six months • Odontocetes nurse for over two years

18. Social behavior • Highly sociable within their respective species; often forming pods • Pods often collaborate in hunting, playing, traveling, and taking care of young • Usually remain in pods throughout their life • Pods are beneficial because hunting is easier in a group; also pods decrease predation

19. Communication • Flukes or Flippers • Slap the surface • Breaching • Leaping from the waters surface • Helps them to attain an elevation of several yards • Spy-hopping • Raise head out of water to investigate objects or potential prey

20. Cont. • Emit various sounds from their head’s • Sperm whales have simple clicks • Humpback whales have complex “songs” • These sounds and echolocation help them navigate, investigate their surroundings, and hunt

21. Echolocation in Mammals • Four orders of mammals use echolocation • Order Cetacea (Whales, Dolphins) • Order Soricomorphia (Shrews) • Order Carnivora (Pinnepeds) • Order Chiroptera (Bats)

22. northern short-tailed shrew-Blarina brevicauda clackhi.nclack.k12.or.us/.../cute%20sea%20lion cas.bellarmine.edu/tietjen/RootWeb/Chiroptera.jpg

23. Echolocation in Cetacean • Important means of navigation • Very well developed in Odontocetes • Very Rapid • Size, shape, and distance of the object can be determined • Anatomy of nasal regions • Ducts and diverticula • Nasal plugs • Air cycled back and forth • All are used to siphon air to create different sounds • Hearing the return echo • Mandible • Small thin bone, that allows the animal to hear through the lower jaw in front

24. Food • Mysticetes • Filter feeders • Use their baleen to strain plankton and other tiny organisms • Odontocetes • Feed on fish, squid, and crustaceans • Larger species eat aquatic birds and mammals (which include other cetaceans)

25. Prey debilitation by Odontoceti • Spermaceti organ • “Shocks” prey so they can eat

26. Ecosystem Roles • Vital roles as consumers • Host a range of internal parasites • Cestodes in their intestines (Tetrabothrium and Diplogonoporus) • Plerocercoids in their blubber (Phyllobothrium and Monorygma) • Trematodes in their stomachs, livers, intestines, and sinuses (Bolbosoma) • Host a range of external parasites • Cookie-cutter sharks (Isistius brasiliensis)

27. Cont. • Cetaceans are mutualists with animals that feed on ectoparasites • Birds have a commensal relationships with cetaceans • Seagulls often follow schools of dolphins and consume small fish stirred up by the feeding cetaceans • Pilotfish (Naucrates ductor) sometimes accompany killer whales and eat scraps from their kills

28. Economical Importance for Humans • Disadvantage • Impact commercial fisheries due to competition for fish • Advantage • Hunted for meat, oil, and blubber in 19th century • Oil is used for lighting and heating • Important for entertainment and tourist industries Killer Whale – Orcinus orca www.destination360.com

29. Human Impact on Cetaceans: Negative • Commercial whaling in the 19th and 20th century decreased the populations of mysticeti • Many small odontocetes threatened by commercial fishing operations • Become entangled in nets and drown, or killed by explosives • They are killed on purpose because fishermen see them as competition • Use of military sonar in the ocean and increase in ocean noise threatens cetaceans • All cetaceans face the threats of pollution and global climate change www.chinadaily.com.cn/world/2006-10/18/xin_46 www.wwf.org.ph/_content/bycatch.jpg

30. Human Impact on Cetaceans: Positive • Commercial whaling was banned in 1986 • Captive breeding programs help critically endangered odontocetes www.onevoice-ear.org/.../dolphins_jobs.jpg members.greenpeace.org/.../source/action_129.jpg

31. References • De Maddalena, Alessandro. June 2004. Giants of the Deep. World and 1, 19:6 • Ellis, E. and A. Poor. 2006. “Cetacea” (on-line), Animal Diversity Web. September 30, 2007 http://animaldiversity.ummz.umich.edu/site/accounts/information/Cetacea.html • Werth, Alexander J. June 2006. Mandibular and Dental Variation and the Evolution of Suction Feeding in Odontoceti. Journal of Mammalogy. 87:3, 579-588