Sperm usually swim in a 3D shimmy: a spiral wave travels down the whippy flagellum and rotates its head in a circle around its long axis. That “bulk swimming” is fine most of the time, but it isn’t a great option when a sperm cell gets close to a surface. That’s when they switch to “slither” mode.
The birds you see above are all ruffs (Philomachus pugnax): wading birds that summer in marshes through Northern Europe and Asia. All three are wearing different forms of breeding plumage. And all of them are male.
Seahorses are famous for flipping the usual reproductive pattern on its head–a seahorse female impregnates the male by laying eggs in his pouch, and the male cares for the developing babies through an 18 day “pregnancy.” But you have to wonder: how does she get her eggs in there?
Last week at Buzzfeed News, Dan Vergano described the surprising results of a paternity test–the first known case of a man fathering the son of a brother he didn’t know existed. It’s an example of a rare genetic condition known as chimerism.
Biologists already knew that one set of neurons play a big role in triggering puberty. A new study shows that these neurons don’t stop working once puberty ends, but keep running through adulthood, serving as a sort of reproductive timer.
A couple of months ago, the Twitter hashtag #JunkOff got biologists to post photos that displayed the extravagant weirdness of plant and animal genitalia. Yesterday, evolutionary geneticist Tom Houslay dared them to write about what animals actually do with their junk.
Lots of human cells are specialized, but I can’t think of any that are as stripped down to a single purpose as spermatozoa. Sperm have just one job, and they’ll die doing it.
Southern rockhopper penguins mate for life, but when biologists used light-based geolocators to track their behavior they found that pairs only spent about 20 to 30 days together each year–just enough time to mate and lay eggs.
A male seahorse gets pregnant when his mate deposits her as-yet-unfertilized eggs into a pouch on his belly. He fertilizes them, then carries the developing embryos until they’re ready to feed themselves. At which point he forcefully shoots them into the world.
Menopause is one of the oddest features of human reproductive biology. Not the hot flashes or the forgetfulness, but the fact that older women lose the ability to have babies. Now researchers say that once it appeared, menopause may have had a ripple effect on human mating that helped create the human pair-bond.
The successful union of egg and sperm in fertilization depends on a sperm cell’s ability to get through an egg’s thick protective coating and latch itself to its membrane. A study published in the journal Andrology yesterday gives us our first look at the protein responsible for the tie-down.
The Smithsonian’s National Zoo has been part of an international effort to breed highly endangered giant pandas in captivity ever since Richard Nixon visited China in 1972. But in 43 years, they’ve had only two solid successes–cubs Tai Shan and Bao Bao. They hope the new twins born this weekend will make it four.
Stunning underwater video by Jose Lachat at Aeon shows you major milestones in the life of an Australian flamboyant cuttlefish: including birth, courtship, and egg-laying before death. If you want to skip right to the sexy part, the mating dance starts at 2:19.
The ratio of newborn boys to girls slightly and consistently leans toward males: around 106 boys are born for every 100 girls. If that seems odd to you, it should: the way sperm form suggests that the ratio of X-sperm to Y-sperm should be exactly 50:50–and scientists are only now beginning to understand why the skew…
When they live in zoos, Mugger crocodiles happily mate and lay eggs. Maybe a little too happily: when they produce two clutches of 25 to 30 eggs each year, a zoo is quickly going be swamped by little croc babies. And rampant habitat loss means that there are fewer places to return them to the wild. What zoos need is…
Technically, the cervix is the bottom chunk of the uterus, a circular plug-like mass of tissue dividing the uterine space from the vagina. But where most of the uterine wall is made of smooth muscle, up to 90% of the cervix is built of stiff and unyielding connective tissue. At least, it’s stiff most of the time.
We all know the sad story of octopus sex, right? They live alone until it’s time to find a mate, they have sex a few times, then the males die. Females live a little longer to lay eggs, but die soon after they hatch. Turns out that the (still officially unnamed) Larger Pacific Striped Octopus breaks all the rules.
Placentas are amazing organs, and we’re learning that they do so much more than simply manage the movement of nutrients and wastes between mother and fetus. In this month’s issue of The Scientist, placenta expert Christopher Coe explains its other roles, including hormonal regulation, iron storage, and immune system…
The global positioning system (GPS) can keep you from getting lost, manage air traffic, and track the migration of endangered species. And in a new study published today by Nature, it’s helped paleontologists understand how an organism that’s been extinct for about 540 million years reproduced.
On July 9th of this year, divers off the coast of Turkey ran across an enormous lump of gelatinous goo which turned out to be one of the largest squid egg masses ever found. That inspired science writer and squid expert Danna Staaf to make this video explaining how all that goo fit inside a much smaller mother squid.