ZOOLOGY SHARKS / ELASMOBRANCHS
Overview <ul><li>Reproductive Organs </li></ul><ul><li>Courtship </li></ul><ul><li>Mating </li></ul><ul><li>Development </...
Female Reproductive Organs <ul><li>Cloacal opening between pelvic fins </li></ul><ul><li>Internal ovaries </li></ul><ul><u...
Reproductive Organs of a Female Porbeagle Shark
Male Reproductive Organs <ul><li>Claspers </li></ul><ul><li>Internal Testes </li></ul><ul><ul><li>paired </li></ul></ul><u...
Reproductive Organs of a Male Porbeagle Shark
Maturity <ul><li>Age and size at maturity differs among species </li></ul><ul><li>Can range from 5 to 18 years to reach br...
Courtship and Mating <ul><li>Little known </li></ul><ul><li>Appears to be violent </li></ul><ul><ul><li>Females have thick...
Mating Mating wounds– bite marks on pectoral fin of female Porbeagle Mating
Mysterious Shark Birth <ul><li>January 2002 </li></ul><ul><li>Henry Doorly Zoo in Nebraska </li></ul><ul><li>Female Bonnet...
Development <ul><li>Three types of development of embryos </li></ul><ul><li>Oviparous </li></ul><ul><ul><li>“ egg laying” ...
Oviparous <ul><li>Considered most primitive </li></ul><ul><li>Most common with bottom dwelling sharks </li></ul><ul><li>Yo...
Oviparous Development 1—Shark egg case after it is laid  2—The egg develops in the shell . 3—The young is fed by the yolk ...
Examples of Egg Cases Egg case of a oviparous shark Egg case of a Port Jackson Shark
Development of a Swell Shark Swell shark develops within a tough, leathery egg case. <ul><li>                             ...
Ovoviviparous <ul><li>Fertilized eggs kept inside mother until born </li></ul><ul><li>Most common form of development </li...
Ovoviviparity Portuguese shark with developing eggs in ovaries
Oophagy and Embryophagy <ul><li>Oophagy– eating eggs within the mother’s uteri </li></ul><ul><li>Examples: </li></ul><ul><...
Viviparous <ul><li>Develop placenta or uterine milk to feed to young </li></ul><ul><li>Similar to development of mammals <...
Examples of viviparous development   <ul><li>Illustration of viviparous embryo showing the yolk sac placenta, yolk sac, ut...
Parturition <ul><li>Number of embryos born to a mother varies </li></ul><ul><li>Typically born after a period of 9 to 12 m...
Great White Shark <ul><li>Maturity at 9 to 15 years </li></ul><ul><li>7 to 11 per litter </li></ul><ul><li>Young 1 meter a...
Bull Sharks <ul><li>Viviparous  </li></ul><ul><li>Sexual maturity reached at 8 to 10 years </li></ul><ul><li>Breed in summ...
Goblin Shark <ul><li>Little is known about reproduction </li></ul><ul><li>Male mature at 2.6 meters </li></ul><ul><li>Ovov...
Whale Shark <ul><li>Only recently began to study </li></ul><ul><li>Up to 300 pups </li></ul><ul><li>Oviparous  </li></ul><...
Sand Tiger Shark <ul><li>Long gestation period </li></ul><ul><li>Large, well developed young at birth </li></ul><ul><li>On...
Silky Shark <ul><li>Not very much known about reproduction </li></ul><ul><li>Live bearing shark </li></ul><ul><li>Litters ...
Port Jackson Shark <ul><li>Return to same area to breed </li></ul><ul><li>Oviparous </li></ul><ul><li>Tough egg case about...
Southern Lantern Shark   <ul><li>Females mature at 62 cm and males at 52 cm total length </li></ul><ul><li>No evidence of ...
Great Hammerhead Shark <ul><li>Viviparous </li></ul><ul><li>Mature at a length of 3 meters </li></ul><ul><li>Litters of 20...
Shortfin Mako <ul><li>Reach maturity at around 2 meters </li></ul><ul><li>Females are usually about 2.8 meters </li></ul><...
Angel Shark <ul><li>Gestation lasts 11 months </li></ul><ul><li>Synchronized by population </li></ul><ul><li>Ovulation occ...
Bonnethead Shark <ul><li>Placental viviparity </li></ul><ul><li>Shortest gestation period known in sharks </li></ul><ul><l...
Spiny Dogfish <ul><li>Gestation period is about two years </li></ul><ul><li>Pup remains in uteri and the fluid surrounding...
Basking Shark <ul><li>Difficult to study </li></ul><ul><li>Observed 25 different courtship episodes </li></ul><ul><li>Matu...
Human Impact <ul><li>Because of slow reproductive rates and small amount of pups, shark populations can not rebuild after ...
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Sharks 12

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  • Sharks 12

    1. 1. ZOOLOGY SHARKS / ELASMOBRANCHS
    2. 2. Overview <ul><li>Reproductive Organs </li></ul><ul><li>Courtship </li></ul><ul><li>Mating </li></ul><ul><li>Development </li></ul><ul><li>Parturition </li></ul><ul><li>Species Examples </li></ul><ul><li>Human Impact </li></ul>
    3. 3. Female Reproductive Organs <ul><li>Cloacal opening between pelvic fins </li></ul><ul><li>Internal ovaries </li></ul><ul><ul><li>Paired </li></ul></ul><ul><ul><li>Two forms </li></ul></ul><ul><li>Eggs travel through ostium to oviduct then through shell gland </li></ul><ul><li>Most eggs develop in uteri </li></ul>Cloacal opening shown on a female shark
    4. 4. Reproductive Organs of a Female Porbeagle Shark
    5. 5. Male Reproductive Organs <ul><li>Claspers </li></ul><ul><li>Internal Testes </li></ul><ul><ul><li>paired </li></ul></ul><ul><li>Urogenital sinus </li></ul><ul><li>Sperm is released into groove of claspers and then into female </li></ul>Claspers of a mature Male shark
    6. 6. Reproductive Organs of a Male Porbeagle Shark
    7. 7. Maturity <ul><li>Age and size at maturity differs among species </li></ul><ul><li>Can range from 5 to 18 years to reach breeding age </li></ul><ul><li>Sharks are usually about 75% of their maximum size at maturity </li></ul><ul><li>Males are on average about 10% smaller than females at maturity </li></ul><ul><li>Females reach maturity about 34% faster than males </li></ul>
    8. 8. Courtship and Mating <ul><li>Little known </li></ul><ul><li>Appears to be violent </li></ul><ul><ul><li>Females have thicker skin than males </li></ul></ul><ul><li>Mate selection shown in some species </li></ul>Courtship and Mating circle of the Basking Shark
    9. 9. Mating Mating wounds– bite marks on pectoral fin of female Porbeagle Mating
    10. 10. Mysterious Shark Birth <ul><li>January 2002 </li></ul><ul><li>Henry Doorly Zoo in Nebraska </li></ul><ul><li>Female Bonnethead gave birth after being in captivity without access to males for three years </li></ul>Bonnethead Shark, Sphyrna tiburo
    11. 11. Development <ul><li>Three types of development of embryos </li></ul><ul><li>Oviparous </li></ul><ul><ul><li>“ egg laying” </li></ul></ul><ul><ul><li>No parental care </li></ul></ul><ul><li>Ovoviviparity/Aplacental </li></ul><ul><ul><li>Most common </li></ul></ul><ul><ul><li>Embryos in uterus with yolk sac </li></ul></ul><ul><li>Viviparity/Placental </li></ul><ul><ul><li>Embryos in uterus with yolk sac and placental connection </li></ul></ul>
    12. 12. Oviparous <ul><li>Considered most primitive </li></ul><ul><li>Most common with bottom dwelling sharks </li></ul><ul><li>Yolk sac for nurishment </li></ul><ul><li>Egg casing to protect young </li></ul><ul><li>Eggs are released near ocean floor with no more parental care </li></ul><ul><li>Egg receives no other care or nutrition </li></ul><ul><li>Development continues for up to a year inside the egg </li></ul><ul><li>Examples: </li></ul><ul><ul><li>Cat Shark </li></ul></ul><ul><ul><li>Port Jackson Shark </li></ul></ul><ul><ul><li>Horn Shark </li></ul></ul><ul><ul><li>Zebra Shark </li></ul></ul><ul><ul><li>Whale Shark </li></ul></ul>
    13. 13. Oviparous Development 1—Shark egg case after it is laid 2—The egg develops in the shell . 3—The young is fed by the yolk sack 4—The developed young breaks away from the shell.
    14. 14. Examples of Egg Cases Egg case of a oviparous shark Egg case of a Port Jackson Shark
    15. 15. Development of a Swell Shark Swell shark develops within a tough, leathery egg case. <ul><li>                                               </li></ul>
    16. 16. Ovoviviparous <ul><li>Fertilized eggs kept inside mother until born </li></ul><ul><li>Most common form of development </li></ul><ul><li>Eggs get nutrition through yolk sac </li></ul><ul><li>Produces large embryos </li></ul><ul><li>Eggs hatch inside mother and then are born </li></ul><ul><li>Provides better shelter </li></ul><ul><li>Examples </li></ul><ul><ul><li>Dogfish Sharks </li></ul></ul><ul><ul><li>Cow Shark </li></ul></ul><ul><ul><li>Angel Shark </li></ul></ul><ul><ul><li>Frill Shark </li></ul></ul><ul><ul><li>Tiger Shark </li></ul></ul>
    17. 17. Ovoviviparity Portuguese shark with developing eggs in ovaries
    18. 18. Oophagy and Embryophagy <ul><li>Oophagy– eating eggs within the mother’s uteri </li></ul><ul><li>Examples: </li></ul><ul><ul><li>Lamnoid Sharks </li></ul></ul><ul><ul><li>Makos </li></ul></ul><ul><ul><li>White Sharks </li></ul></ul><ul><ul><li>Threshers </li></ul></ul><ul><ul><li>Crocodile Sharks </li></ul></ul><ul><ul><li>False Catsharks </li></ul></ul><ul><li>Embryophagy—eat siblings in uteri </li></ul><ul><li>Example: </li></ul><ul><ul><li>Sand Tiger Shark </li></ul></ul>35cm Porbeagle Shark distended stomach of this specimen is full of egg yolk from ingested eggs 50cm Shortfin Mako Shark embryo distended stomach, full of egg yolk
    19. 19. Viviparous <ul><li>Develop placenta or uterine milk to feed to young </li></ul><ul><li>Similar to development of mammals </li></ul><ul><li>Considered the most advanced form </li></ul><ul><li>Embryo develops internally </li></ul><ul><li>Has an umbilical cord attached to mother </li></ul><ul><li>Gestation is typically 9 months </li></ul><ul><li>Examples: </li></ul><ul><ul><li>Hammerhead sharks </li></ul></ul><ul><ul><li>Requiem sharks </li></ul></ul>
    20. 20. Examples of viviparous development <ul><li>Illustration of viviparous embryo showing the yolk sac placenta, yolk sac, uterus and embryo </li></ul><ul><li>Hammerhead shark showing umbilical cord </li></ul>
    21. 21. Parturition <ul><li>Number of embryos born to a mother varies </li></ul><ul><li>Typically born after a period of 9 to 12 months </li></ul><ul><li>Most born tail first </li></ul><ul><li>Usually give birth in shallow coastal areas </li></ul>Birth of a baby shark
    22. 22. Great White Shark <ul><li>Maturity at 9 to 15 years </li></ul><ul><li>7 to 11 per litter </li></ul><ul><li>Young 1 meter at birth </li></ul><ul><li>Gestation time unknown </li></ul><ul><li>Ovoviviparity and oophagy, but canabalism as once believed </li></ul><ul><li>Give birth every two years </li></ul>                                                                                                                      
    23. 23. Bull Sharks <ul><li>Viviparous </li></ul><ul><li>Sexual maturity reached at 8 to 10 years </li></ul><ul><li>Breed in summer </li></ul><ul><li>Litters up to 13 pups </li></ul><ul><li>Breed in brackish waters </li></ul>
    24. 24. Goblin Shark <ul><li>Little is known about reproduction </li></ul><ul><li>Male mature at 2.6 meters </li></ul><ul><li>Ovoviviparious </li></ul>
    25. 25. Whale Shark <ul><li>Only recently began to study </li></ul><ul><li>Up to 300 pups </li></ul><ul><li>Oviparous </li></ul><ul><li>Don’t know where or when give birth or what early life is like </li></ul>
    26. 26. Sand Tiger Shark <ul><li>Long gestation period </li></ul><ul><li>Large, well developed young at birth </li></ul><ul><li>Only one or two pups </li></ul><ul><li>Ovoviviparity, oophagy, and Embryophagy </li></ul>
    27. 27. Silky Shark <ul><li>Not very much known about reproduction </li></ul><ul><li>Live bearing shark </li></ul><ul><li>Litters of 2 to 14 </li></ul><ul><li>Pup on edges of continental shelves </li></ul><ul><li>Newborns stay in nursery areas </li></ul>
    28. 28. Port Jackson Shark <ul><li>Return to same area to breed </li></ul><ul><li>Oviparous </li></ul><ul><li>Tough egg case about 7-8 cm wide and 15 cm long </li></ul><ul><li>Mature at 8-14 years </li></ul>
    29. 29. Southern Lantern Shark <ul><li>Females mature at 62 cm and males at 52 cm total length </li></ul><ul><li>No evidence of a seasonal reproductive cycle </li></ul><ul><li>Ovulation occurs when ova reach diameter of 40-45 cm </li></ul><ul><li>Average number of ova is 12.7 </li></ul><ul><li>Sexes segregate in adults except to mate </li></ul>
    30. 30. Great Hammerhead Shark <ul><li>Viviparous </li></ul><ul><li>Mature at a length of 3 meters </li></ul><ul><li>Litters of 20 to 40 pups </li></ul><ul><li>Young are born during summer </li></ul><ul><li>70 cm in length </li></ul>
    31. 31. Shortfin Mako <ul><li>Reach maturity at around 2 meters </li></ul><ul><li>Females are usually about 2.8 meters </li></ul><ul><li>Size at birth is about 70 cm </li></ul><ul><li>Litter size 4 to 16 </li></ul><ul><li>Placental viviparity </li></ul><ul><li>Oophagous </li></ul>
    32. 32. Angel Shark <ul><li>Gestation lasts 11 months </li></ul><ul><li>Synchronized by population </li></ul><ul><li>Ovulation occurs in summer and birth takes place in Spring </li></ul><ul><li>Gestation has two phases </li></ul>
    33. 33. Bonnethead Shark <ul><li>Placental viviparity </li></ul><ul><li>Shortest gestation period known in sharks </li></ul><ul><li>Store sperm for months </li></ul><ul><li>Use hormones to regulate cycle </li></ul>
    34. 34. Spiny Dogfish <ul><li>Gestation period is about two years </li></ul><ul><li>Pup remains in uteri and the fluid surrounding it resembles sea water </li></ul><ul><li>Reasons for sea water environment not known </li></ul>
    35. 35. Basking Shark <ul><li>Difficult to study </li></ul><ul><li>Observed 25 different courtship episodes </li></ul><ul><li>Mature sharks were 5 to 8 meters </li></ul><ul><li>Took about 1.8 hours in courtship rituals </li></ul>
    36. 36. Human Impact <ul><li>Because of slow reproductive rates and small amount of pups, shark populations can not rebuild after being over fished by humans </li></ul><ul><li>Environmental degradation and development threatens the nursery areas of many species </li></ul><ul><li>Shark finning slaughters hundreds of thousands of sharks each year </li></ul><ul><li>Could take decades to centuries for populations to recover </li></ul>Shark fins on sale in Hong Kong market                                                                                          
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