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Fish Markets: Cooperation and Competition in the Undersea "Economy"

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You probably know that hermit crabs live in shells. What you might not know is that really nice shells to call home are a scarce commodity, and hermit crabs consequently have some pretty cool ways of optimizing the ways they acquire and occupy their shells.

A study of the purple-clawed hermit crabs (Coenobita clypeatus) on an island off the Belizean coast reveals that the crabs fill shells using "vacancy chains"—social structures through which vacancies in certain resources propagate through a population, like the ways humans fill jobs and apartments.

Synchronous and Asynchronous Vacancy Chains

The hermit crabs were observed to use two types of vacancy chain: synchronous and asynchronous. An asynchronous chain is when one crab moves into a new, empty shell and abandons its old one to be found by another crab, which abandons its own for another crab to find, etc. With this type of chain, shell switching is sequential and the crabs experience little to no interference or competition. They have the opportunity to investigate any vacant shells they find and can directly compare their current shell with a new shell by switching back and forth between the two. It's sort of like when you look at apartments that have just been moved out of and are available immediately or in the near future. If you take one of those apartments, someone else can check out and move into yours, someone else will move into theirs, etc., in an orderly fashion.

Synchronous vacancy chains are more social and much more interesting. They start off with "waiters," crabs that hang around a shell that's too big for them, and wait for a bigger crab to come along so that if the big crab moves in to the vacant shell, the waiter can grab their more appropriately-sized hand-me-down shell. (The researchers note that the decision to wait, and how long to wait, based on previous experience, provides some evidence that the crabs are smarter than we thought.)

As a crowd gathers—a crowd always gathers, but no one knows how; the researchers think the waiters may use vocal or chemical signals to draw attention to the vacancy—the crabs queue up by size, from largest to smallest. Once the largest crab switches into the vacant shell, each crab climbs into a new shell as it's vacated by the slightly larger crab ahead of it, quickly shuffling vacancies (literally) down the chain. A similar type of chain happens in college towns across America every fall. Students spend months "lining up" by finding apartments, packing and labeling boxes, and then—BAM!—a few thousand kids move in and out of apartments in one day.

Here's a synchronous chain in action.

The Undersea Service Industry

Moving away from real estate and into the service industry, animals still behave kind of like humans. They partner with other animals that provide the high-quality goods and services, cheat each other, and then threaten to take their business elsewhere in order to get what they want.

"Cleaner fish," which remove dead skin and parasites from other fish in a mutually beneficial relationship (they get a meal, and the other fish get groomed), have been known to make their "clients" wait for service and cheat them by feeding on healthy tissue or mucous instead of parasites. Clients don't have many options for ensuring good service. They can't demand their mucous back or complain to the Better Business Bureau. What they can do is go get cleaned somewhere else.

A study by a University of California, Santa Barbara biologist found that individuals of one type of cleaner fish near French Polynesia, the luestreak cleaner wrasse, have to compete for access to their preferred clients, the ornate butterfly fish. This competition gives clients with easy access to multiple "cleaner stations" - areas where the cleaner fish hang out and do their thing - the ability to get better service from cleaners, who apparently are cued to the fact that their customers can easily take their business elsewhere and are discouraged from cheating them.

This story originally appeared in a different format on Matt's website.

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The Surprising Link Between Language and Depression
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Skim through the poems of Sylvia Plath, the lyrics of Kurt Cobain, or posts on an internet forum dedicated to depression, and you'll probably start to see some commonalities. That's because there's a particular way that people with clinical depression communicate, whether they're speaking or writing, and psychologists believe they now understand the link between the two.

According to a recent study published in Clinical Psychological Science, there are certain "markers" in a person's parlance that may point to symptoms of clinical depression. Researchers used automated text analysis methods to comb through large quantities of posts in 63 internet forums with more than 6400 members, searching for certain words and phrases. They also noted average sentence length, grammatical patterns, and other factors.

What researchers found was that a person's use (or overuse) of first-person pronouns can provide some insight into the state of their mental health. People with clinical depression tend to use more first-person singular pronouns, such as "I" and "me," and fewer third-person pronouns, like "they," "he," or "she." As Mohammed Al-Mosaiwi, a Ph.D. candidate in psychology at the University of Reading and the head of the study, writes in a post for IFL Science:

"This pattern of pronoun use suggests people with depression are more focused on themselves, and less connected with others. Researchers have reported that pronouns are actually more reliable in identifying depression than negative emotion words."

What remains unclear, though, is whether people who are more focused on themselves tend to depression, or if depression turns a person's focus on themselves. Perhaps unsurprisingly, people with depression also use more negative descriptors, like "lonely" and "miserable."

But, Al-Mosaiwi notes, it's hardly the most important clue when using language to assess clinical depression. Far better indicators, he says, are the presence of "absolutist words" in a person's speech or writing, such as "always," "constantly," and "completely." When overused, they tend to indicate that someone has a "black-and-white view of the world," Al-Mosaiwi says. An analysis of posts on different internet forums found that absolutist words were 50 percent more prevalent on anxiety and depression forums, and 80 percent more prevalent on suicidal ideation forums.

Researchers hope these types of classifications, supported by computerized methods, will prove more and more beneficial in a clinical setting.

[h/t IFL Science]

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The ‘Scully Effect’ Is Real: Female X-Files Fans More Likely to Go Into STEM
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Fox

FBI agent Dana Scully is more than just a role model for remaining professional when a colleague won't stop talking about his vast governmental conspiracy theories. The skeptical doctor played by Gillian Anderson on The X-Files helped inspire women to go into STEM (science, technology, engineering, and math) careers, according to a new report [PDF] from the Geena Davis Institute on Gender in Media, which we spotted at Fast Company.

“In the world of entertainment media, where scientists are often portrayed as white men wearing white coats and working alone in labs, Scully stood out in the 1990s as the only female STEM character in a prominent, prime-time television role,” the report explains. Previously, anecdotal evidence has pointed to the existence of a “Scully effect,” in which the measured TV scientist—with her detailed note-taking, evidence-based approach, and desire to autopsy everything—inspired women to seek out their own science careers. This report provides the hard data.

The Geena Davis Institute surveyed more than 2000 women in the U.S. above the age of 25, a significant portion of whom were viewers of The X-Files (68 percent) and women who had studied for or were in STEM careers (49 percent). While the survey didn’t ask women whether watching Dana Scully on The X-Files directly influenced their decision to be a scientist, the results hint that seeing a character like her on TV regularly did affect them. Women who watched more of the show were more likely to say they were interested in STEM, more likely to have studied a STEM field in college, and more likely to have worked in a STEM field after college.

While it’s hard to draw a direct line of causation there—women who are interested in science might just be more inclined to watch a sci-fi show like The X-Files than women who grow up to be historians—viewers also tended to say Scully gave them positive impressions of women in science. More than half of respondents who were familiar with Scully’s character said she increased their confidence in succeeding in a male-dominated profession. More than 60 percent of the respondents said she increased their belief in the importance of STEM. And when asked to describe her, they were most likely to say she was “smart” and “intelligent” before any other adjective.

STEM fields are still overwhelmingly male, and governments, nonprofits, schools, activists, and some tech companies have been pushing to make the field more diverse by recruiting and retaining more female talent. While the desire to become a doctor or an engineer isn’t the only thing keeping STEM a boy’s club, women also need more role models in the fields whose success and accomplishments they can look up to. Even if some of those role models are fictional.

Now that The X-Files has returned to Fox, perhaps Dana Scully will have an opportunity to shepherd a whole new generation of women into the sciences.

[h/t Fast Company]

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