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Spiders Enjoy the Occasional Vegetarian Meal

A jumping spider covered in pollen from a hibiscus. Image credit: © Nick Hobgood, University of South Pacific

Spiders eat more than the flies they snare in their webs. While we often imagine spiders as carnivorous predators, their diets are more diverse. Sometimes they eat fish. And, according to a new report in Journal of Arachnology, some arachnids are also more than willing to partake in vegetarian meals.

For the study, the team, led by biologist Martin Nyffeler at the University of Basel in Switzerland, collected 95 pre-existing reports in scientific literature of spiders eating plants. At least 10 families of spiders, from every continent but Antarctica, have been observed eating some kind of plant matter.

The jumping spider Bagheera kiplingi in Mexico eating a Beltian body, a leaf tip found on acacia plants. Image Credit: © Robert L. Curry, Villanova University

A concurrent study by Nyffeler in the journal PECKHAMIA focuses just on jumping spiders, the most prominent spider group that engages in this behavior. A total of 60 percent of the plant-eating events documented in the Arachnology study came from jumping spiders. And most of the reports of spiders eating plants came from warmer areas of the globe.

While the Central American jumping spider Bagheera kiplingi subsists on an almost entirely vegetarian diet, most spiders enjoy plant meals more sparingly. Some feed on nectar, some eat honeydew, while others collect pollen (like the jumping spider covered in pollen from a hibiscus, pictured in the first image above) in addition to eating insects. This could be an adaptation to allow spiders to survive when insects are scarce, or be a nutritional supplement. It’s possible that a larger number of spider species supplement their diets with the occasional vegetarian meal, but further research is necessary. 

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Animals
10 Notable Gestation Periods in the Animal Kingdom
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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?

2. HIPPOS: 8 MONTHS

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.

3. GIRAFFE: 14-15 MONTHS

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.

4. KILLER WHALE: 17 MONTHS

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.

6. GERBILS: 25 DAYS

Hey, they get off pretty easy.

7. GORILLAS: 8.5 MONTHS

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

8. BLACK BEAR: 220 DAYS

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. 

9. PORCUPINE: 112 DAYS

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.

10. WALRUS: 15 MONTHS

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

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Goldfish Can Get Depressed, Too
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Don’t believe what Pixar is trying to sell you: Fish are not exactly brimming with personality. In aquariums, they tend to swim in circles, sucking up fragments of food and ducking around miniature treasure chests. To a layperson, fish don’t appear to possess concepts of happy, or sad, or anything in between—they just seem to exist.

This, researchers say, is not quite accurate. Speaking with The New York Times, Julian Pittman, a professor at the Department of Biological and Environmental Sciences at Troy University, says that fish not only suffer from depression, they can be easily diagnosed. Zebrafish dropped into a new tank who linger at the bottom are probably sad; those who enthusiastically explore the upper half are not.

In Pittman’s studies, fish depression can be induced by getting them “drunk” on ethanol, then cutting off the supply, resulting in withdrawal. These fish mope around the tank floor until they’re given antidepressants, at which point they begin happily swimming near the surface again.

It’s impossible to correlate fish depression with that of a human, but Pittman believes the symptoms in fish—losing interest in exploring and eating—makes them viable candidates for exploring neuroscience and perhaps drawing conclusions that will be beneficial in the land-dwelling population.

In the meantime, you can help ward off fish blues by keeping them busy—having obstacles to swim through and intriguing areas of a tank to explore. Just like humans, staying active and engaged can boost their mental health.

[h/t The New York Times]

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