Stories tagged sexual reproduction

Plates and spikes: It appears Stegosaurus couples would have had a lot of stuff to work around when they mated
Plates and spikes: It appears Stegosaurus couples would have had a lot of stuff to work around when they matedCourtesy Mark Ryan
Although, for some dinosaur species, like the heavily-ornamented Stegosaurus, getting busy might have been hell. Brian Switek writes about the delicate subject at Smithsonian.com.

Folks, this is exciting news! Reproductive biologists think they've found the secret that makes sperm move - specifically, how this male reproductive cell knows when to begin swimming toward the female egg. For those of you who slept through biology class or had teachers that couldn't divulge the gritty details, let's just say that sexual reproduction is a lot more complicated than most of us realize (hint: it doesn't involve a stork, unless you happen to be a stork). Thankfully, some researchers at the University of California have found a way to study the inner workings of human sperm cells, discovering how differences in pH between male and female bodies triggers a chain reaction that gets sperm going. Why does this matter? By understanding how male reproductive cells work, scientists might be able to better address problems of infertility, or design new forms of contraception. While the researchers involved in this study admit that a male birth control pill probably isn't going to appear anytime soon, this discovery does point to new possibilities.

May
18
2009

Baby Tucuxi, unaware of impending attack...
Baby Tucuxi, unaware of impending attack...Courtesy Matt Walker

Reading about mutinous mammals is waaaay better than writing the final paper of my undergrad career! Agreed? Yes, well to the point. Now I've heard that dolphins will bite ya if provoked, but that even that is extremely rare.

It is not uncommon for mammals to practice infanticide. It is practiced for a variety of reasons. Males may attack young of their own species so the mother is more receptive to further reproduction from that male. It is also practiced when resources are low and a groups well-being is in danger from lack of food. Both males and females of a species will practice infanticide.

Among their scientific class Cetaceans, a class including dolphins, whales, and porpoises violent behavior including infanticide is very rare and largely undocumented...until now!

Tucuxi Dolphins, native to the Amazon basin were observed practicing infanticide in Brazil by Mariana Nery, of the Southern University of Chile in Valdivia, and Sheila Simao, of the Federal Rural University of Rio de Janeiro, Brazil. Adult male Tucuxi are known to be aggressive but they rarely exhibit this behavior towards younger individuals. Nery and Simao observed six adult Tucuxi separate a newborn Tucuxi calf from its mother. They proceeded to ram into it, hold it under water, and toss it into the air. When the mother attempted to intervene four of the males herded her away. While the adult males attacked the calf the mother floated on her back. This behavior indicates either passiveness, or more likely a signal that she is receptive to sexual behavior. I believe she did this to distract the adult males from injuring or killing the calf, and to let them know she could reproduce again. To no avail. Sadly, the mother was seen days later without her calf.

Jan
30
2009

Into flow charts?: This is a flow chart of a relationship. Start at the bioluminescent spike, and end at the parasitic gonads.
Into flow charts?: This is a flow chart of a relationship. Start at the bioluminescent spike, and end at the parasitic gonads.Courtesy steev-o
It’s Friday (T.G.I.F.), Buzzketeers, and you all know what that means. That’s right, it’s time for the Science Buzz Friday Relationship Extravaganza! (S.B.F.R.E.)

I know how much y’all like relationships, and how much you like talking about them, so it’s only natural that you clicked on the S.B.F.R.E. so quickly. But that’s not all! See, here at the S.B.F.R.E., “relationship” is also a code word for… S-E-X! Oh, naughtiest of naughties! It’s a red-letter day! Relationships and S-E-X-ual science… y’all had better sit down.

Seriously, sit down. Make yourselves comfortable. Now, I want y’all to know that this is a safe space, and we should be free to say whatever we’re feeling. Good, good… I think we’re about ready to start.

So… I understand that you feel like he has some real problems in communicating his feelings?

Why do you think that is?

No, I’m sorry, let’s let him finish—we’ll all have a chance to talk, and it’s his turn right now.

OK. I think I see what you’re saying. How do you want him to communicate? What do you wish he would say to you?

And how does that make you feel? Is that something you can do? OK… Why do you think you’re not being listened to?

I see.

Well, let’s look at it this way: at least y’all aren’t anglerfish. You know anglerfish, right, Buzzketeers? Anglerfish include those awful deep sea fish, with the big eyes, and teeth all over the place, and a glowing spike sticking out of their awful, lumpy heads. You know what I’m talking about. You saw those pictures, and then learned that they were only a few inches long, but were still kind of grossed out. And maybe some holier-than-thou biologist type pointed out to you that they weren’t gross, they were just fish that had made some spectacular adaptations to their environment, and were just living their lives like every other animal.

Well, don’t worry, you were right in the first place: angler fish really are awful and gross.

See, when they first discovered these creepy anglerfish, scientists were only finding female specimens. No males at all. So where’s the relationship relationship?

Well, eventually they did find some males, and some remarkable observations were made. The male anglerfish were pretty normal in their youth, but once they reached sexual maturity, their digestive systems degenerate. So they are unable to feed themselves. Naturally, what a mature male needs to do at that point is find a sugar momma. And fast (because, again, they’re starving to death). When the male tracks down a female anglerfish, he bites her, latching on to her body with his teeth. Enzymes in the male then break down its own mouth, as well as the female’s body, so that the two fish fuse together, to the point where they even share blood vessels. A source of sustenance now secured, the male kind of “lets itself go,” if you will. But instead of gaining weight and watching too much TV, the body of the male anglerfish, still fused with the female, degenerates, eventually becoming just a pair of gonads that hang off the female. When the first female anglerfish were discovered, scientists thought that they had parasites hanging off of them. Nope. Those were the remains of male anglerfish.

When the female is ready to release eggs, the gonads sense the change in hormone levels in the blood that still flows to them, and they release sperm, so that the eggs can be fertilized, and more horrible anglerfish can be created.

I don’t know who has it worse here—the female that has to nourish a pair of parasitic testicles (or multiple pairs), or the male, who has to latch on to a female to survive, and then becomes a pair of parasitic testicles. Either way, though, I think you’ll agree that your own messed up relationship seems pretty ideal right now, doesn’t it?

So remember, until the next Science Buzz Friday Relationship Extravaganza, keep your emotions bottled up, and if you’re ever feeling bummed out about things, just think of the never-lonely anglerfish.