Marine Mammal Reproductive Structures, Strategies, & Patterns MARE 390 Dr. Turner

1. Marine Mammal Reproductive Structures, Strategies, & Patterns MARE 390 Dr. Turner

2. Testes, One, Two “We're talking about S-E-X in front of the C-H-I-L-D-R-E-N." – Maude Flanders "What?!?! Sex cauldron? I thought they closed that place down“ – Krusty the Clown Phocid – testes inguinal Otariids – testes scrotal Walrus – inguinal; scrotal during mating Pinnipeds – bacculum (penis bone) Cetaceans & Sirenians – fibroelastic penis

3. Sex Your Seal Ma’am? Teats & position of genital opening

4. I’m Too Sexy for my Dolphin Distance between Anal & Genital slit ♀ both within common groove ♂ separation between; testes internal cavity

5. Is that a manatee in your pocket..? Distance between Anal & Genital slit ♀ short distance ♂ separation between; testes internal cavity

6. Reproduction ↑ Fitness of female = ↑ Fitness offspring Females: cost of egg, pregnancy, lactation, postnatal care Males: invest energy in competition with other males (physical & sperm)

7. Reproduction Pinniped, Ursid, mustellid mating typically on land; some phocids shallow water

8. Reproduction Cetaceans – belly-to-belly

9. Reproduction Sirenians – belly-to-belly

10. Gestation Placental mammals – 18 days to 22-24 months Marine mammals: sea otter (6-7mo) to Sperm whale (16.5mo) ↑ Gestation time = ↑ Fetus size

11. Gestation Mass (kg) Gest.(mo) Int.(Y) Harbor seal 11 9-12 1 N. Elephant 40 11 1 N. fur seal 6 12 1 Walrus 50 14-16 2-4 Porpoises 8 8-11 n/a Bottlenose 20 12 n/a Sperm Whale 1050 14-16 3 Blue Whale 2500 11-12 2-3

12. Gestation Mass (kg) Gest.(mo) Int.(Y) Manatee 30 12-13 2-5 Dugong n/a 14 3-7 Sea Otter 2 6-7 1 Polar Bear 0.7 8 2-4

13. Delayed Implantation Delayed implantation – development of the blastocyst is slow or negligible Is obligate in pinnipeds, ursids, and mustelids Period of delayed implantation allows flexibility of timing of parturition, and is controlled by photoperiod

14. Delayed Implantation Dev.Gest(mo) Delay Impl.(mo) Harbor seal 8-9.5 1.5-3 N. Elephant 7 4 N. fur seal 8 4 Walrus 10-11 4-5 Sea Otter 4 2-3 Polar Bear 4 4

15. Pinniped Reproduction

16. Pinniped Reproductive Cycle

17. Cetacean Reproductive Cycle

18. Migration Change in latitude in grey whales

19. Mating Systems High degree of variability in reproductive systems 2 major groups: polygyny & promiscuity Polygyny – successful male mating with several females Promiscuity – males associate with several females during a variable amount of time

20. Evolution of Polygyny

21. Mating Systems Driven by sexual selection – competition 1. Contest comp. – Direct comp. over ♀ 2. Endurance comp. – ♂ Endure longer 3. Scramble comp. – Search/locate ♀ 4. Mate choice comp. – Entice/attract ♀ 5. Sperm comp. - ↑ Quality/Quantity of sperm

22. Pinniped Mating Systems Male otariids typically utilize Resource Defense Polygyny Characteristics: 1. Males arrive before females 2. Females receptive close to place of birth 3. Rookery substrate stable but discontinous 4. Few aggressive interactions once dominance is established

23. Otariid Mating Systems Most males defend Territories – not females

24. Pinniped Mating Systems Male phocids typically utilize Female (Harem) Defense Polygyny Characteristics: Most dominant male (Alpha) defends females from other subordinate males

25. Phocid Mating Systems Most males defend Females – not Territories

26. Phocid Mating Systems Elephant Seals – High level polygyny – alpha controls large harems

27. Phocid Mating Systems Monk Seals – Low level polygyny – alpha controls individual females

28. Odobenid Mating Systems Walrus – either display a Female-Defense Polygyny (like Phocids) or a Lek-like behavior (similar to Otarriids)

29. Odobenid Mating Systems Lek - gathering of males, of certain animal species, for the purposes of competitive mating display

30. Cetacean Mating Systems Mysticetes – little social behavior beyond mother-calf pair Many utilize sperm competition – attempt to dilute out other males sperm Odontocetes – exist in groups of variable size for persist longer than any member’s life span

31. Odontocete Social Groups Arranged as schools, pods, or units Size varies by species & geographic location Mating structure a mixture of promiscuous & polygynous Male-male competition – sexual dimorphism

32. Spinner Social Groups Aggregate in schools of up to 100 individuals subgroups – up to 12 Subgroups travel in echelon formation

33. Orca Social Groups

34. Sperm Whale Social Groups Similar to orca groups Males leave pods and form juvenile groups Solitary adult males rove among female groups

35. Sirenian Mating Systems Similar to mysticetes- little social structure past mother-calf pairs Animals congregate into herds during summer months to breed Dugongs found in larger associations than manatees

36. Lactation Strategies Most energetically expensive aspect of reproduction Best interest to pass as much energy as possibly even at expense of future offspring 3 strategies: Fasting, Foraging Cycle, Aquatic Nursing

37. Fasting Lactation Strategy Example: Northern elephant seal Duration of fasting: All of lactation Duration of lactation: Short (4-weeks) Fat content of milk: High (55%) Pups forage during lactation: No

38. Foraging Cycle Lactation Strategy Example: Antarctic fur seal Duration of fasting: Variable (few days) Duration of lactation: Intermediate (4-months) Fat content of milk: Intermediate (40%) Pups forage during lactation: No

39. Aquatic Nursing Lactation Strategy Example: Walrus Duration of fasting: Short (hours-days) Duration of lactation: Long (2-3 years) Fat content of milk: Low (2-3%) Pups forage during lactation: Yes

40. Lactation Length(w) Fat% Prot.% Harbor seal 3.4 50 9 N. Elephant 4 54 5-12 N. fur seal 18 42 14 Walrus 100 14-32 5-11 Porpoise 32 46 11 Bottlenose 76 14 12-18 Sperm Whale 100 15-35 8-10 Blue Whale 24-28 35-50 11-14

41. Lactation Length(w) Fat% Prot.% Manatee 52 n/a n/a Dugong 78 n/a n/a Sea Otter 20-30 21-26 9-12 Polar Bear 130 17-36 9-13

42. Got Milk!