David Funk
David Funk

Male Crickets Bribe Their Mates With 'Gummy Bears'

David Funk
David Funk

Everybody likes getting presents. It’s this fact that makes gift-giving such an important form of social currency: People give presents to celebrate and reward one another, and use them as apologies, distractions, and bribes. But humans aren’t the only ones who give gifts for selfish reasons. 

A new study authored by scientists from the University of Exeter and the Max Planck Institute for Chemical Ecology and published last week in PLOS ONE, has found that a male cricket’s postcoital “nuptial gift” to his mate is really more of a gift to himself. The gift, a gelatinous blob called a spermatophylax, can manipulate a female cricket into becoming a mother.

Nuptial gifts are a common feature of courtship in the animal kingdom, especially for insects. Before, during, or after sex, male animals present their mates with food or pretty objects. Gifts of food deliver an extra boost of protein or nutrients. Those nutrients will be passed on to the female’s eggs, making the next generation a little hardier and stronger.

But the nuptial gift of the decorated cricket, Gryllodes sigillatus, does none of these things. The sweet and chewy spermatophylax has no nutritional value whatsoever. “They’re a sham,” Illinois State University entomologist Scott Sakaluk told Nautilus last year. The gift is “the equivalent of a gummy bear,” he said. “Gummy bears are really tasty, but you can’t live off gummy bears.”

A spermatophylax doesn’t just fall out of the sky; the male cricket has to devote a lot of resources to making it. And he wouldn’t do that if it weren’t worth his time. So what’s it for? 

Manipulation. It looks so innocent, but the gummy bear is a Trojan horse. By eating the male cricket’s gift, the female cricket unwittingly takes part in ensuring her tricky mate’s legacy.

Scientists already knew about the first phase of the subterfuge: distraction. After mating, the male cricket deposits a small packet of sperm and a big nuptial gift at the tip of the female’s ovipositor. (You can see both in the image above; the spermatophylax is the big, clear blob, while the sperm packet is smaller and cloudy.) 

Unlike the gift, the sperm packet actually is nutritious, and the female will eat it if she gets the chance. But before she can get to it, she finds the gift. It can take her up to 50 minutes to eat the cricket candy—which is, on average, as long as it takes for the sperm to transfer into her body. The bigger the gummy bear, the better the chance that a male’s sperm will be successful in their quest.

But the deception goes so much deeper. In their study published in PLOS ONE, the researchers reported that compounds in the cricket’s nuptial gift seem to change the female cricket’s body and behavior.

The team found two types of proteins in the spermatophylax. One is protective, and keeps the female cricket’s gut from digesting the second protein. That protein may have two purposes: first, to beef up the female’s reproductive system, and second, to kill her sex drive and keep her from mating with anyone else.

So the cricket’s nuptial gift may be less like a gummy bear and more like a gummy vitamin—one the female cricket has no idea she’s taking. 

Big Questions
What Makes a Cat's Tail Puff Up When It's Scared?

Cats wear their emotions on their tails, not their sleeves. They tap their fluffy rear appendages during relaxing naps, thrash them while tense, and hold them stiff and aloft when they’re feeling aggressive, among other behaviors. And in some scary situations (like, say, being surprised by a cucumber), a cat’s tail will actually expand, puffing up to nearly twice its volume as its owner hisses, arches its back, and flattens its ears. What does a super-sized tail signify, and how does it occur naturally without help from hairspray?

Cats with puffed tails are “basically trying to make themselves look as big as possible, and that’s because they detect a threat in the environment," Dr. Mikel Delgado, a certified cat behavior consultant who studied animal behavior and human-pet relationships as a PhD student at the University of California, Berkeley, tells Mental Floss. The “threat” in question can be as major as an approaching dog or as minor as an unexpected noise. Even if a cat isn't technically in any real danger, it's still biologically wired to spring to the offensive at a moment’s notice, as it's "not quite at the top of the food chain,” Delgado says. And a big tail is reflexive feline body language for “I’m big and scary, and you wouldn't want to mess with me,” she adds.

A cat’s tail puffs when muscles in its skin (where the hair base is) contract in response to hormone signals from the stress/fight or flight system, or sympathetic nervous system. Occasionally, the hairs on a cat’s back will also puff up along with the tail. That said, not all cats swell up when a startling situation strikes. “I’ve seen some cats that seem unflappable, and they never get poofed up,” Delgado says. “My cats get puffed up pretty easily.”

In addition to cats, other animals also experience piloerection, as this phenomenon is technically called. For example, “some birds puff up when they're encountering an enemy or a threat,” Delgado says. “I think it is a universal response among animals to try to get themselves out of a [potentially dangerous] situation. Really, the idea is that you don't have to fight because if you fight, you might lose an ear or you might get an injury that could be fatal. For most animals, they’re trying to figure out how to scare another animal off without actually going fisticuffs.” In other words, hiss softly, but carry a big tail.

10 Notable Gestation Periods in the Animal Kingdom

The gestation periods of the animal kingdom are varied and fascinating. Some clock in at just a few weeks, making any human green with envy, while others can last more than a year. Here are 10 notable gestation times for animals around the globe. The lesson? Be thankful that you’re not a pregnant elephant.

1. ELEPHANTS: 640-660 DAYS

Elephants are pregnant for a long time. Like really, really long. At an average of 95 weeks, the gestation period is more than double the length of a human pregnancy, so it shouldn't come as a shock that female elephants don't often have more than four offspring during their lifetimes. Who has the time?


A photo of a mother hippo and her baby in Uganda

Yes, it takes less time to make a hippopotamus than it takes to make a human.


Baby giraffes can weigh more than 150 pounds and can be around 6 feet tall. Another fascinating tidbit: giraffes give birth standing up, so it's pretty normal for a baby to fall 6 feet to the ground.


There’s a reason for the long wait: after that 17 months, Baby Shamu emerges weighing anywhere from 265 to 353 pounds and measuring about 8.5 feet long. Yikes.

5. OPOSSUM: 12-13 DAYS

A baby opossum wrapped up in a blanket

Blink and you'll miss it: This is the shortest gestation period of any mammal in North America. But since the lifespan of an opossum is only two to four years, it makes sense.


Hey, they get off pretty easy.


It's not a huge surprise that their gestational periods are pretty similar to ours, right?


A pair of black bear cubs

Also less than a human. Interestingly, cubs might only be 6 to 8 inches in length at birth and are completely hairless. 


This is the longest gestation period of any rodent. Thankfully for the mother, porcupine babies (a.k.a. porcupettes) are actually born with soft quills, and it's not until after birth that they harden up.


Baby walruses? Kind of adorable. They certainly take their sweet time coming out, though.


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