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These organisms don’t just dabble in out-of-the-box delicacies, they make some really bizarre dietary choices!

Hosted by: Hank Green

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Sources:
Fruit eating crocodile
http://www.guidetrainingcourses.com/wp-content/uploads/2013/10/Diet-of-the-Nile-Crocodile-Crocodylus-niloticus-in-the-Okavango-Delta-Botswana.pdf
http://www.thehindu.com/features/metroplus/society/fruiteaters/article5455640.ece
https://archive.org/stream/journalofbomb40121938bomb#page/336/mode/2up
https://www.rwrefuge.com/uploads/4/9/4/2/49423019/platt_et_al__2013-_seed_dispersal_crocodilians.pdf
http://www.bioone.org/doi/abs/10.1656/058.013.0304

Salad eating shark
http://www.sciencemag.org/news/2018/01/meet-world-s-first-salad-eating-shark
https://news.nationalgeographic.com/2017/06/bonnethead-sharks-eat-seagrass/
http://sicb.org/meetings/2018/schedule/abstractdetails.php?id=1123
http://www.sci-news.com/biology/bonnethead-sharks-consume-digest-seagrass-05611.html
http://german.bio.uci.edu/images/PDF/Jhaveri%20et%20al.%20%282015%29%20CBPA_print.pdf

Snail slurping snakes
https://zookeys.pensoft.net/articles.php?id=24523
http://biopublisher.ca/index.php/be/article/view/490/593
https://www.researchgate.net/publication/274335066_Feeding_behavior_of_the_snail-eating_snake_Dipsas_indica
https://bmcevolbiol.biomedcentral.com/articles/10.1186/1471-2148-14-58
https://www.ncbi.nlm.nih.gov/pubmed/18262581
https://insider.si.edu/2018/07/newly-discovered-snakes-use-curved-teeth-to-pry-snails-from-their-shells/

Nectar-drinking mongoose
https://onlinelibrary.wiley.com/doi/abs/10.1111/aje.12225
https://www.newscientist.com/article/dn27716-voracious-carnivores-caught-knocking-back-sugary-flower-nectar/

Shell-crunching caterpillar:
https://academic.oup.com/ae/article/51/4/245/2474782
http://www.eartharchives.org/articles/meet-the-moth-with-a-taste-for-tortoise/
http://explorer.natureserve.org/servlet/NatureServe?searchName=Ceratophaga+vicinella
https://books.google.ca/books?id=jya9Pc7agAAC&pg=PT74&lpg=PT74&dq=tineid+digestion&source=bl&ots=MTrAwRc9uM&sig=CMjTY-k5BAAkl64LsHcIhA2V894&hl=en&sa=X&ved=2ahUKEwiauMy4ks_cAhVO1IMKHSpXB6UQ6AEwAHoECAAQAQ#v=onepage&q=tineid%20digestion&f=false
https://www.tandfonline.com/doi/abs/10.1080/00222933.2014.939731#.VMDUUyd3_Ds

Porta-potty pitcher plant:
http://www.sciencemag.org/news/2011/01/carnivorous-plant-feasts-bat-dung
http://rspb.royalsocietypublishing.org/content/282/1801/20142675
http://rsbl.royalsocietypublishing.org/content/7/3/436

Tear-drinking moth
https://www.researchgate.net/publication/6552800_Malagasy_birds_as_hosts_for_eye-frequenting_moths
https://www.newscientist.com/article/dn10826-moths-drink-the-tears-of-sleeping-birds-/
https://link.springer.com/article/10.1007/BF02526872
https://www.sciencenewsforstudents.org/article/these-insects-thirst-tears
[♩INTRO].

You might sometimes venture outside your culinary comfort zone. Maybe you’ve eaten toasted crickets, or you’ve sampled escargot on a trip to France.

But the seven organisms on this list don’t just dabble in out-of-the-box delicacies, they make some really bizarre dietary choices. Like, you just don’t expect sharks to eat plants, or, well, anything to live on a diet of dead turtle shells. But apparently, having an adventurous palate has its advantages, evolutionarily speaking.

There are at least 13 species of crocs and alligators in the order crocodilia that eat fruit, for example. These unexpected frugivores include infamous predators like the American crocodile, Nile crocodile and Saltwater crocodile. But by far the best studied is American alligator.

They’re known to consume basically anything meaty, including adorable little dogs that venture too close to bodies of freshwater in the southeastern US. But they also eat a huge range of fruit, nuts, seeds and other plants at least 34 different species. And no one is really sure why.

The leading theory is that they’re just generalist feeders, so they eat whatever’s available. But some biologists think they seek out nuts as gastroliths: stones that are swallowed to aid digestion. You see, crocs and gators have pretty rude table manners and do not chew their food.

They swallow it whole and leave the work to their gizzard: a thickly walled portion of the stomach that grinds up food. Having something hard in there can help break down tougher chunks of meat. There are also some that think all this fruit and nut eating is purely accidental.

But... there have been sightings by locals of gators plucking kumquats right off a tree. And in 1871, a French naturalist noted. Mexican crocodiles are so fond of avocados that some people started calling the fruits “alligator pears”.

So it seems unlikely that all this fruit-eating is unintentional. The bonnethead shark is a small member of the hammerhead family, and like its relatives, its usual diet consists of shrimps, molluscs and crabs. But it also likes to supplement that protein with a nice salad of seagrass.

In fact, stomach content analysis has shown that seagrass can make up as much as 62% of the shark’s diet. At first, scientists thought the sharks were eating all that grass by accident because juvenile sharks seemed to be eating more of grass than adults. They thought the young sharks were just clumsily chomping on some grass as they learned to hunt.

But a study presented at the 2018 Society for Integrative and Comparative. Biology conference tells a different story. When sharks were kept in a tank and fed a diet consisting of 90% seagrass and 10% meat, they all gained weight.

And tracers put in the grass were found in the sharks’ blood, revealing that they’d actually absorbed nutrients from the grass. The researchers think an enzyme called b-glucosidase in the sharks’ stomachs might be helping them break down the fibrous cellulose in the plants. This enzyme is also found in the guts of seaweed eating fish and three species of plankton eating sharks.

But it’s never before been found in a species scientists thought was a meat eater. The sharks probably can’t survive on a purely vegetarian diet, but they seem to be more omnivorous than scientists originally thought. In France, escargots, or snails, are a luxurious treat.

It turns out there’s a group of snakes that also likes to indulge in this slippery delicacy. The family Dipsadini (otherwise known as the “goo-eating” snakes) contains almost 80 species. Some eat snails and slugs as a side dish, while others are totally molluscivorous, meaning feed exclusively on snails and their kin.

And they have special adaptations to cope with such slimy meals. Almost all of the dedicated snail-eaters have a lot of loose, folded skin on the base of their mouths and teeth that curve backward. These allows them to clamp down on the snail shell and squeeze much of their lower jaw into it.

Then, with a few jerky movements, they slurp the snail out. Many also have enlarged infralabial glands in the floor of their mouths which secrete a protein-rich fluid out of holes near the front of the lower jaw. Scientists think this is comprised of toxins that immobilize the snakes’ prey, or help loosen snails from their shells, though no one is entirely sure.

Snails might seem like a strange diet choice for a snake, but biologists think it evolved because of competition. By scaling trees and feeding on less popular fare, these snakes were able to carve out a niche for themselves. The Indian Grey Mongoose is a ferocious little carnivore with a protein-heavy diet of eggs, insects, frogs, scorpions, crabs and fish.

But it also has quite the sweet tooth. Camera trap footage from 2015 caught this meat-eater slinking up to sugarbush flowers and drinking their nectar. And that’s just not something carnivores usually do.

If they vary their fleshy diet, it’s with fruit, not nectar. So the scientists were really surprised to see these furry meat-eaters downing nectar. The flowers do have a bit of a cheese-like smell, so it’s possible the animals were initially drawn to what smelled like carbs or protein.

But the researchers think they return for the sugar rush and the nectar certainly has no shortage of that. It’s about 30% sugar by weight. It seems a few slurps and these guys were hooked.

For one of the species of sugarbush observed, the mongooses accounted for a little less than half of all visits recorded. They were even seen carefully pushing leaves aside to gain access to that sweet juice. And after the mongooses had their fill, they left with snouts covered in pollen, which made researchers think they could be acting as pollinators although that’s a hypothesis that needs further testing.

Tineidae moth caterpillars are notorious for eating sweaters. But one species munches on something much creepier than your clothes: he shells of dead gopher tortoises. Ceratophaga vicinella belongs to a sub-group of Tineidae moths that feed on the protein keratin, usually from things like horns, hooves, or hair.

You can spot them by looking for hard, brown tubes these are called larval casings, and they’re how the caterpillars protect themselves. In 2005, researchers in southern Florida noticed similar casings on the shells of dead gopher tortoises and concluded that the shells were the main food source of a new species. But why the super restrictive and, let’s be honest, somewhat disturbing, diet?

Well, all moths need to eat protein so they can spin their cocoons. They could eat leaves or your sweaters for their protein fix, but keratin is everywhere, if you have the tools to digest it. These moths have super acidic stomachs and 29 different kinds of protein-breaking enzymes called proteases sloshing around in their guts.

And since no other moths in the area digest tortoise shells, they’ve got an exclusive ticket to an abundant food source. Or, what was an abundant food source. The only problem though with being such a picky eater is that you’re in trouble if your food disappears and that’s exactly what’s happening.

Gopher tortoises are declining due to habitat loss, being squashed by cars, poaching and disease. And if the tortoises disappear, so too will this strange little moth with its weird diet. Pitcher plants are carnivorous plants that usually feast on bugs and such that they lure to their funnels using attractive scents.

At the bottom of that funnel is an acidic digesting pool which does exactly what it sounds like it does. But the Raffles' pitcher plant found in the jungles of Borneo doesn’t just eat insects. It also eats guano.

Yes... bat poop. Raffles’ pitchers actually come in five growth forms one of which, called elongata, grows high up in the trees. Because of its long, slender shape, fewer insect-attracting compounds, and low levels of digestive fluid, it’s not actually very good at trapping insects.

Its insect capture rates are about 7 times lower than other varieties of the same species. What elongata varieties are good at, though, is acting as a nice little hotel for woolly bats. Their narrower shape and lower digestive pool mean the bats can snuggle up in the pitchers during the day to stay safe from predators and the elements.

And the plants don’t mind this intrusion because the bats’ provide them with nitrogen through their guano and urine. Yummy! As gross as that might sound, the pitchers can get about 39% of their nitrogen needs from the bats’ waste enough to balance the fact that they don’t catch as many insects.

So this bat-pitcher plant relationship is a nice example of mutualism, where both parties benefit from a particular interaction. Imagine it’s the middle of the night in the forests of Madagascar, and you’re a bird peacefully trying to get a little sleep. While you dream of tasty grubs, you might unwittingly become the target of the Madagascar tear drinking moth.

This 26 millimeter-long moth lands near a bird’s eye and jabs its sharp, 10 millimeter long, barbed proboscis under the unsuspecting bird’s eyelid. It then proceeds to slurp tears right out of the tear duct a feeding style known as lachryphagy. It’s not weird that they crave such a salty beverage.

Lots of butterflies and moths engage in what’s called puddling, where they take sips of muddy puddles or other moist things like rotting fruit to get a boost of nutrients and fluid. But for Madagascar tear drinking moths, tears aren’t a treat they’re a complete meal packed with all the protein and minerals they need. And because the tears are the main component of the moth’s diet, scientists have labelled them ophthalmotropic moths.

There are other tear drinkers, too, but they usually go for large mammals or reptiles the Madagascan moth is the only one to feed on birds. Stealing from an animal that could kick or bite at you might seem risky, but biologists think it may actually be safer than regular puddling. That’s because it’s unlikely the moth’s usual predators want to risk waking a sleeping giant.

And for what it’s worth, the birds don’t actually seem to feel anything. Some biologists wonder if the moths inject an anaesthetic when they stab their mouthparts in, but so far, no one has looked to see. These diets might seem bizarre, or even gross, but they all offer the species on our list something useful.

Whether that’s a way to survive stiff competition, get extra nutrients, or make up for bad hunting skills, they show that diversifying your meals can be a winning strategy. And hey, we all love a little variety in our diets, so why shouldn’t an alligator eat a kumquat? Thanks for watching this episode of SciShow!

If you think these animals have some unexpected meals, you should see which species made our list of vegetarian animals that actually eat meat. [♩OUTRO].