1. Marine Mammals: Part 1 Marine Vertebrates: Lecture 7

2. Notochord; Dorsal, hollow nerve tube; pharynx with slits, post-anal tail (with segmented muscle bands) Cranium formed from neural crest cells Plus paired appendages (2 pair)

3. Class Mammalia: Key characteristics  Mammary glands (milk production)  Hair  Endothermic  Efficient circulatory system (4-chambered heart)  Efficient respiratory system (diaphragm)  Internal fertilization  Relatively large brains  Differentiation of teeth  Development of malleus and incus in middle ear (reptiles already have stapes)

4. Order Carnivora Ursidae: polar bears Mustilidae: sea otters

5. (Sub)order Pinnipedia Phocidae Otariidae Odobenidae

6. Order Sirenia Manatees and dugongs

7. Order Cetacea Suborder Odontoceti Suborder Mysticeti

8. Osmotic balance Acquiring water  Diet  Drink  Metabolically-produced water Water loss  Skin, sweat glands, exhalation Excretion of water and ions  Kidneys Concentrating ability mirrors reptile/bird salt glands

9. Thermoregulation Heat retention: Fur vs. blubber  Dry fur is a more efficient insulator than blubber  Specializations of marine mammal fur Fur seals and sea otters Polar bears Regulation of heat via blood flow changes  Regulating flow to capillary beds Esp. hairless regions of body  Countercurrent exchange Large size and shape  Surface to volume low…  Comparison to land mammals

10. Order Carnivora Family Ursidae

11. Adaptations to marine existence Streamlining  No prominent shoulder humps  Small head; small ears Adaptations for swimming  Paws are larger, partly webbed  Also allows for more even distribution of weight on ice  Long neck (how of value?)  Dog paddle! Thermoregulation  Thicker fur  Clear, hollow guard hairs  These may actually absorb ultraviolet light)  >2x the size of grizzlies (up to 1800 pounds)

12. Habitat/Feeding ecology Circumpolar distribution  Stable, but not continuous, (mostly) annual pack ice  Can’t find prey without Seal specialists; will also hunt other marine mammals  Follow leads or finding holes made by their prey. Male vs. female foraging  Males venture further out onto less-stable pack ice Avoid the most unstable ice near the ice edge  ideal pupping grounds for seals  Females remain on more-stable pack ice closer to den sites. Locate ringed seal pups in dens beneath snow or in small ice caves in the pack ice  Use their sense of smell

13. Life History Mating  April/May  ~3:1 Male:Female “operational sex ratio” (Why?)  Induced ovulation:  Delayed implantation Maternity dens (~ mid- October) Young born in December/January Young are 1-1.5 pounds at birth!  Usually two. Break out of dens (~ March/April)  Young ~25-30 pounds  Female is hungry… Cubs with mother for 2.5 years

14. Conservation status: Threatened Key threats  Habitat loss Global climate change  Harvesting  Water pollution

15. Order Carnivora Family Mustilidae: sea otters!

16. Overview/ adaptations to marine existence Size: quite small for a marine mammal  45-65 pounds Dive stats: 120 feet; 4 minutes breath-hold Thermoregulation (water is 30-50  F)  Fur  High metabolic rate (25% of body weight per day) Swim on their backs Use webbed hindflippers in an alternate motion for propulsion; also use their flattened tail.  Relatively slow for marine mammals, ~2-3 kt cruising speed. Forelimbs are very mobile, resemble arms and hands for collecting/manipulating food

17. Habitat/feeding ecology Live in kelp forests  Wrap themselves and their young in the kelp... Feed on a wide variety of benthic invertebrates  sea urchins, abalone, crabs, sea stars, clams, scallops, etc…  May play important role in maintenance of kelp beds Tool users (bang creatures with exoskeletons, shells, and even endoskeletons on rocks) Kelp itself provides some protection from predation.

18. Sea otter: Historic distribution

19. Sea otter: Current distribution

20. Conservation status: Endangered  CA sea otter population: steady, some slow growth  AK (Aleutian Islands) huge decline Orca predation  Major threats Coastal pollution Oil spills Cat litter and Toxoplasma gondii Decline of other marine mammals…