Gauthier via Wikimedia Commons // CC BY-SA 3.0
Gauthier via Wikimedia Commons // CC BY-SA 3.0

Darwin’s Obsession With Barnacle Penises Makes a Lot of Sense Now

Gauthier via Wikimedia Commons // CC BY-SA 3.0
Gauthier via Wikimedia Commons // CC BY-SA 3.0

Barnacle penises are amazing. That’s not a direct quote from Charles Darwin, but it might as well have been; the naturalist was obsessed with the little crustaceans’ very large members. Now scientists say he missed out on one of the best barnacle facts: Many species can change the shape and size of their penises to suit their environment. A report of the findings was published in the journal Integrative & Comparative Biology

Relative to its body size, the barnacle has the largest penis in the animal kingdom. This is, of course, not just some hilarious joke by Mother Nature—the length is necessary in order for these sessile (non-moving) animals to reach one another. Barnacles grow in colonies clamped to rocks, piers, boats, and sometimes large animals like whales. They feed by extending little feathery sensory appendages called cirri into the water to catch plankton. 

In their resting state, barnacles are simultaneous hermaphrodites, meaning that they have both male and female parts. In many species, mating season begins when one barnacle’s egg glands begin to swell, rendering it “functionally female.” That barnacle releases chemicals into the water that tell its neighbors that it’s time to get busy. In response, they become “functional males,” unfurling their long, flexible penises into the water like party horns, questing for the right opening.   

For obvious reasons, these bizarre sexual adaptations fascinated Darwin. The naturalist devoted seven years of his life to studying barnacles, in the process compiling descriptions of the “probosciform” (elephant trunk–like) penises of hundreds of species. (We are not making this up.) 

A small sample of Darwin's barnacle collection. Image credit: FunkMonk via Wikimedia Commons // CC BY 3.0

Darwin was determined to learn all he possibly could about the animals, their anatomy, and their behavior. When he got wind that a friend of a friend had been lucky enough to see barnacle sex in action, he wrote a pretty intense letter, peppering his contact with questions. An excerpt:

Was the probosciformed penis inserted into more than one individual? For about how long [and how many] times was it inserted? Was it inserted deeply & at which end of valves? Especially did the recipient individual continue during the times exerting its cirri? Did it keep its opercula valves widely open for the reception of the organ? I am anxious to know whether this recipient was a willing agent or adulterer. or whether it was a case of rape by act. If the recipient was in full vigour, I think it wd be impossible to insert anything without its consent. Were the specimens under water at times? 

Who was the observer that I might check his authority. 

We told you he was obsessed. But he was far from the only one. Darwin’s love of (and thorough notes on) the lumpy little animals left a scientific legacy that continues to this day. Marine biologists J. Matthew Hoch and Daniel T. Schenk of Nova Southeastern University and Quest University’s Christopher J. Neufeld have spent years studying barnacles. They collected their research—and the findings of others—in the recent review paper, and they came to some very interesting conclusions. 

Barnacle reproductive organs. Image credit: J. Matthew Hoch, Nova Southeastern University

“We know that barnacles are robust in their ability to overcome environmental challenges and to mate successfully,” they write. Sometimes they do that by stretching their penises, making them thicker, or changing their shape altogether. “In the most extreme circumstances,” they say, “it degenerates and is shed during the first post-mating molt and is re-grown for the next mating season." 

These animals are “so robust” in their sexual prowess, the authors say, that in one case a barnacle with two penises was still able to mate successfully.

“As barnacle biologists,” they write, “we understand and identify with Darwin’s excitement about barnacle reproduction and look forward to new knowledge generated through the modern-day comparative approach that has yielded so many new insights.”

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These Sparrows Have Been Singing the Same Songs for 1500 Years

Swamp sparrows are creatures of habit—so much so that they’ve been chirping out the same few tunes for more than 1500 years, Science magazine reports.

These findings, published in the journal Nature Communications, resulted from an analysis of the songs of 615 adult male swamp sparrows found in six different areas of the northeastern U.S. Researchers learned that young swamp sparrows pick up these songs from the adults around them and are able to mimic the notes with astounding accuracy.

Here’s what one of their songs sounds like:

“We were able to show that swamp sparrows very rarely make mistakes when they learn their songs, and they don't just learn songs at random; they pick up commoner songs rather than rarer songs,” Robert Lachlan, a biologist at London’s Queen Mary University and the study’s lead author, tells National Geographic.

Put differently, the birds don’t mimic every song their elders crank out. Instead, they memorize the ones they hear most often, and scientists say this form of “conformist bias” was previously thought to be a uniquely human behavior.

Using acoustic analysis software, researchers broke down each individual note of the sparrows’ songs—160 different syllables in total—and discovered that only 2 percent of sparrows deviated from the norm. They then used a statistical method to determine how the songs would have evolved over time. With recordings from 2009 and the 1970s, they were able to estimate that the oldest swamp sparrow songs date back 1537 years on average.

The swamp sparrow’s dedication to accuracy sets the species apart from other songbirds, according to researchers. “Among songbirds, it is clear that some species of birds learn precisely, such as swamp sparrows, while others rarely learn all parts of a demonstrator’s song precisely,” they write.

According to the Audubon Guide to North American Birds, swamp sparrows are similar to other sparrows, like the Lincoln’s sparrow, song sparrow, and chipping sparrow. They’re frequently found in marshes throughout the Northeast and Midwest, as well as much of Canada. They’re known for their piercing call notes and may respond to birders who make loud squeaking sounds in their habitat.

[h/t Science magazine]

ZUMA Press, Inc., Alamy
5 Fascinating Facts About Koko the Gorilla
ZUMA Press, Inc., Alamy
ZUMA Press, Inc., Alamy

After 46 years of learning, making new friends, and challenging ideas about language, Koko the gorilla died in her sleep at her home at the Gorilla Foundation in Woodside, California on June 21, 2018. Koko first gained recognition in the late 1970s for her ability to use sign language, but it was her friendly personality that made her a beloved icon. Here are five facts you should know about the history-making ape.


Francine "Penny" Patterson, then a graduate student at Stanford University, was looking for an animal subject for her inter-species animal communication experiment in the early 1970s when she found a baby gorilla at the San Francisco Zoo. Originally named Hanabiko (Japanese for "fireworks child," a reference to her Fourth of July birthdate), Koko took to signing quickly. Some of the first words Koko learned in "Gorilla Sign Language," Patterson's modified version of American Sign Language, were "food," "drink," and "more." She followed a similar trajectory as a human toddler, learning the bulk of her words between ages 2.5 and 4.5. Eventually Koko would come to know over 1000 signs and understand about 2000 words spoken to her in English. Though she never got a grasp on grammar or syntax, she was able to express complex ideas, like sadness when watching a sad movie and her desire to have a baby.


Not only did Koko use language to communicate—she also used it in a way that was once only thought possible in humans. Her caretakers have reported her signing about objects that weren't in the room, recalling memories, and even commenting on language itself. Her vocabulary was on par with that of a 3-year-old child.


Koko was the most famous great ape who knew sign language, but she wasn't alone. Michael, a male gorilla who lived with Koko at the Gorilla Foundation from 1976 until his death in 2000, learned over 500 signs with help from Koko and Patterson. He was even able to express the memory of his mother being killed by poachers when he was a baby. Other non-human primates have also shown they're capable of learning sign language, like Washoe the chimpanzee and Chantek the orangutan.


Koko received many visitors during her lifetime, including some celebrities. When Robin Williams came to her home in Woodside, California in 2001, the two bonded right away, with Williams tickling the gorilla and Koko trying on his glasses. But perhaps her most famous celebrity encounter came when Mr. Rogers paid her a visit in 1999. She immediately recognized him as the star of one of her favorite shows, Mister Rogers' Neighborhood, and greeted him by helping him take off his shoes like he did at the start of every episode.


Koko was never able to have offspring of her own, but she did adopt several cats. After asking for a kitten, she was allowed to pick one from a litter for her birthday in 1985. She named the gray-and-white cat "All Ball" and handled it gently as if it were her real baby, even trying to nurse it. She had recently received two new kittens for her 44th birthday named Ms. Gray and Ms. Black.


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