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The giant whale shark is an elusive quarry for study , particularly when it comes to pick out the spotted shark ' mating and reproduction . But a new analysis of uncommon whale shark embryos suggests that female may save up spermatozoan after mating , queue up multiple litters of the filter - feeding fish .
The study , a genetic analysis of 29 conceptus save from a femalewhale sharkcaught near Taiwan in 1995 , found that despite being in very different stage of development , all of the embryo had the same father .
The filter-feeding whale shark can grow as long as a school bus.
Though cautious about drawing close from the study of a undivided shark , survey leader Jennifer Schmidt , a biologist at the University of Illinois at Chicago said the data suggest distaff whale shark mate once , salt away the sperm cell and fertilize their own eggs ( which develop into embryos ) as they ’re produce .
" If conjugation fall out randomly when a manly and female happen to see , this would provide the female with a sorting of reproductive ' insurance policy policy , ' " Schmidt secern LiveScience . " She has sperm available to stay to fertilize her own bollock even if she does n’t encounter another grownup male person . "
blate giant
At anywhere from 18 to 40 feet ( 5 to 12 meters ) in length , giant shark are the largest Pisces the Fishes specie . They live in tender waters worldwide , but research worker usually get to study them only in coastal water where untried juvenile males cluster to feed . Much of the shark ' lives seem to occur in the unfastened sea , where they ’re hard to note . No one has ever seen giant shark mate .
Nor are pregnant female person a common sight . The first ( of just three ever account ) was caught in 1995 in Taiwan . She had 304 embryos in her uterus , grade in development from 16 - in ( 42 - cm ) embryo in egg pillowcase to 2 - foot ( 64 - centimeter)-long , near - full term embryos hold up costless in the womb . ( Like some other Pisces and reptilian species , whale sharks hatch from ball inside the mother ’s uterus and are then born live . )
After 15 years , only 29 of the conceptus had been freeze and saved , but they ran the gamut from very young to almost executable . Using genetic depth psychology — essentially , a shark paternity test — the researchers were able-bodied to determine that all of the sharks very likely had the same dad .
Sperm savers
The findings surprise the researcher , because most sharks that have been studied give nascence to litters of half - siblings after females have mated with tidy sum of male sharks at once . Though it ’s possible the female whale shark mate with the same male again and again over metre , that form of monogamy is unheard of in sharks . More in all likelihood , Schmidt said , the shark met once and the female person stored the sperm , enabling her to start new pregnancies at her leisure .
By queuing up births , the sharks may be able to extend more embryos at once . They may also avert putting all their eggs in one basket , so to verbalize . By giving parentage to lot of babies all at once , other shark might risk their materialization becoming an all - you - can - eat - buffet for predators . give birth a few at a time in different locations spreads out that risk .
Schmidt is n’t trusted how long whale sharks can lay in spermatozoon , or how many times they mate . Firm ending about a whole species ca n’t be draw and quarter from one shark . It ’s possible , though statistically unlikely , that there was another shark pa , whose resulting embryos were n’t saved for examination . It ’s also possible that whale sharks domate with multiple males , but that this particular shark had n’t . A final possibility is that two sharks with near - identical DNA contributed to the bedding material , and the current trial run missed the differences between the two . As the test is capable of picking an individual out of a population of a billion whale shark , this last hypothesis is very unlikely , the researchers write online Aug. 4 in the diary Endangered Species Research .
Replicating the study will be hard . The whale shark islisted as " vulnerable"by the International Union for Conservation of Nature , and it is protect from gaining control around the reality . The few that are found in marine museum are usually less than 25 years old and not sexually matured . Female adult only amass in a few spot worldwide , mostly in the Sea of Cortez and near the Galapagos Islands . Researchers are now try out to understand what ’s especial about those spots and whether pregnant females can be read there .
