Natures wonders: marine mammal sex (Introduction)

by David Turell @, Monday, April 24, 2017, 14:48 (1166 days ago) @ David Turell

Both sexes had to evolve their organs to work together under water:

"Most species of marine mammal are known to have unusually shaped genitalia, but until now there has been little research into how the actual mechanics of sex work.

“'While it may seem intuitive that the penis fits well into the vagina during copulation, the biomechanics and details of the anatomical fit can be quite complex and have seldom been explored,” says Orbach.

“'Whales, dolphins and porpoises have unusual vaginal folds, spirals and recesses that the penis and sperm must navigate through to successfully fertilise the egg.”

"Studying the ins and outs of cetacean and pinnipede sex presents some obvious challenges. To circumvent these, Orbach and his team amassed a collection of reproductive organs from animals that had died of natural causes.

"They then developed a system to inflate the penises to full turgidity and used computed tomography scans to investigate how, and how deeply, they penetrated the appropriate vaginal tract, and at which points contact was made.

"With this information, the team then made silicone models of the vaginal system, allowing the scientists a clear view of the mechanics involved. The information permitted some informed deductions about how the male and female reproductive systems co-evolved.

"Orbach set out to understand how marine mammals deal with a very different mating environment to those occupied by terrestrial mammals. Porpoises and dolphins, for instance, have to perform in a liquid three-dimensional space, and also have to contend with the potential problem of seawater leaking into the uterus.

"Surprisingly, the work is one of the few times the way in which male and female marine mammal anatomy interacts has been studied.

“'Most previous research on genitalia has focused on the penis,” notes Orbach.
He adds that his findings have potential to greatly improve the results of captive breeding programs, particularly those using artificial insemination."

Comment: Obviously special changes have to take place to both sets of sex organs to keep sea water out. The real issue is how do the two sexes coevolve at the same time and in ways to continue reproduction, if it is all by chance mutations. Not likely. Back to saltation. The same issue arises when considering the enlarging human head in the newborn babies and the shape and size of the female pelvis to accommodate it. Further as bipedalism developed the birth canal changed, another complication. Coevolution by chance? Darwin theory cannot handle this issue.

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