Episode 341: The Leaf Sheep and the Mold Pig

Thanks to Murilo and an anonymous listener for their suggestions this week!

Further reading:

The ‘sheep’ that can photosynthesize

Meet the ‘mold pigs,’ a new group of invertebrates from 30 million years ago

A leaf sheep:

Shaun the sheep:

A mold pig:

Show transcript:

Welcome to Strange Animals Podcast. I’m your host, Kate Shaw.

This week let’s learn about two animals that sound like you’d find them on a farm, but they’re much different than their names imply. Thanks to Murilo for suggesting the leaf sheep, which is where we’ll start.

The leaf sheep isn’t a sheep or a leaf. It’s actually a type of sea slug that lives in tropical waters near Japan and throughout much of coastal south Asia. The reason it’s called a leaf sheep is because it actually looks a lot like a tiny cartoon sheep covered with green leaves instead of wool.

Back in episode 215 we talked about the sea bunny, which is another type of sea slug although it’s not closely related to the leaf sheep. The leaf sheep is even smaller than the sea bunny, which can grow up to an inch long, or about 25 mm. The leaf sheep only grows about 10 mm long at most, which explains why it wasn’t discovered until 1993. No one noticed it.

The leaf sheep’s face is white or pale yellow with two tiny black dots for eyes set close together, which kind of makes it look like Shaun the Sheep. It also has two black-tipped protuberances that look like ears, although they’re actually chemoreceptors called rhinophores. The rest of its body is covered with leaf-shaped spines called cerata, which are green and often tipped with pink, white, or black. This helps disguise it as a plant, but there’s another reason why it’s green.

The leaf sheep eats a particular kind of algae called Avrainvillea, which looks like moss or fuzzy carpet. While algae aren’t exactly plants or animals, many do photosynthesize like plants. In other words, they transform sunlight into energy to keep them alive. In order to photosynthesize, a plant or algae uses a special pigment called chlorophyll that makes up part of a chloroplast in its cells, which happens to be green.

The leaf sheep eats the algae, but it doesn’t digest the chloroplasts. Instead, it absorbs them into its own body and uses them for photosynthesis. That way it gets nutrients from eating and digesting algae and it gets extra energy from sunlight. This is a trait shared by other sea slugs in the superorder Sacoglossa. Because they need sunlight for photosynthesis, they live in shallow water, often near coral reefs.

When the leaf sheep’s eggs hatch, the larvae have shells, but as they mature they shed their shells.

This is a good place to talk about cyanobacteria, which was requested ages ago by an anonymous listener. Cyanobacteria mostly live in water and are also called blue-green algae, even though they’re not actually classified as algae. They’re considered bacteria, although not every scientist agrees. Some are unicellular, meaning they just consist of one cell, while others are multicellular like plants and animals, which means they have multiple cells specialized for different functions. Some other cyanobacteria group together in colonies. So basically, cyanobacteria looked at the chart of possible life forms and said, “yes, thanks, we’ll take some of everything.” That’s why it’s so hard to classify them.

Cyanobacteria photosynthesize, and they’ve been doing so for far longer than plants–possibly as much as 2.7 billion years, although scientists think cyanobacteria originally evolved around 3.5 billion years ago. The earth is about 4.5 billion years old and plants didn’t evolve until about 700 million years ago.

Like most plants also do, cyanobacteria produce oxygen as part of the photosynthetic process, and when they started doing so around 2.7 billion years ago, they changed the entire world. Before then, earth’s atmosphere hardly contained any oxygen. If you had a time machine and went back to more than two billion years ago, and you forgot to bring an oxygen tank, you’d instantly suffocate trying to breathe the air. But back then, even though animals and plants didn’t yet exist, the world contained a whole lot of microbial life, and none of it wanted anything to do with oxygen. Oxygen was toxic to the lifeforms that lived then, but cyanobacteria just kept producing it.

Cyanobacteria are tiny, but there were a lot of them. Over the course of about 700 million years, the oxygen added up until other lifeforms started to go extinct, poisoned by all that oxygen in the oceans and air. By two billion years ago, pretty much every lifeform that couldn’t evolve to use or at least tolerate oxygen had gone extinct. So take a deep breath of life-giving oxygen and thank cyanobacteria, which by the way are still around and still producing oxygen. However, they’re still up to their old tricks because they also produce what are called cyanotoxins, which can be deadly.

That brings us to another animal in our imaginary farm, the mold pig. It’s not a pig or a mold, and unlike the leaf sheep and cyanobacteria, it’s extinct. At least, we think it’s extinct.

The mold pig is a microinvertebrate only discovered in 2019. The only reason we know about it at all is because of amber found in the Dominican Republic, on an island in the Caribbean Sea. As we’ve discussed in past episodes, especially episode 108, amber is the fossilized resin of certain types of tree, and sometimes the remains of small animals are found inside. Often these animals are insects, but sometimes even tinier creatures are preserved that we would otherwise probably never know about.

The mold pig was about 100 micrometers long, or .1 millimeter. You’ve probably heard of the tardigrade, or water bear, which we talked about in episode 234, and if so you might think the mold pig was a type of tardigrade just from looking at it, since it looks similar. It had four pairs of legs like tardigrades do, but while scientists think they were related, and that the mold pig was probably also related to mites, it was different enough that it’s been classified in its own genus and may need to belong to its own phylum. Its official name is Sialomorpha.

The mold pig probably ate mold, fungus, and microscopic invertebrates. It lived around 30 million years ago, and right now that’s about all we know about it. There’s a good chance that it still survives somewhere in the world, but it’s so tiny that it’s even easier to overlook than the leaf sheep. Maybe you will be the person who rediscovers its living descendants.

You can find Strange Animals Podcast at strangeanimalspodcast.blubrry.net. That’s blueberry without any E’s. If you have questions, comments, or suggestions for future episodes, email us at strangeanimalspodcast@gmail.com. If you like the podcast and want to help us out, leave us a rating and review on Apple Podcasts or Podchaser, or just tell a friend. We also have a Patreon at patreon.com/strangeanimalspodcast if you’d like to support us for as little as one dollar a month and get monthly bonus episodes.

Thanks for listening!

Episode 278: Gender Diverse Animals

This week is Connor’s episode, and we’re going to learn about some animals that don’t conform to “typical” gender roles, one way or another.

I’ll be at ConCarolinas this week, from June 3 through 5, including recording a live crossover episode with Arcane Carolinas!

Further reading:

Species of algae with three sexes that all mate in pairs identified in Japanese river

How a microbe chooses among seven sexes

Facultative Parthenogenesis in California Condors

The sparrow with four sexes

Chinstrap penguins make good dads:

Laysan albatrosses make good moms:

Black swans make good dads:

Some rams really like other rams (photo by Henry Holdsworth):

New Mexico whiptail lizards are all females:

California condor females don’t always need a male to produce fertilized eggs:

Clownfish change sex under some circumstances:

The white-throated sparrow essentially has four sexes:

You are awesome (photo by By Eric Rolph)!

Show transcript:

“Hey y’all, this is Connor. Welcome to a very special Pride Month edition of the Strange Animals Podcast.”

This week we have Connor’s episode! We decided to make it the very last episode in our Kickstarter month so that it’s as close to the month of June as possible, because June is Pride Month and our episode is about gender-diverse animals! Don’t worry, parents of very young children, we won’t be discussing mating practices except in very general terms.

Pride month celebrates people’s differences when it comes to gender expression and sexuality. That’s why its symbol is the rainbow, because a rainbow is made up of all different colors the same way there are different kinds of people. Sometimes people get angry when they hear about Pride month because they think there are only two genders, and that those two genders should only behave in certain ways. Pffft. That’s not even true when it comes to animals, and humans are a lot more socially complicated.

For instance, let’s start by talking about a humble creature called algae. If you remember episode 129, about the blurry line between animals and plants, you may remember that algae isn’t actually a plant or an animal. Some species resemble plants more than animals, like kelp, but they’re not actually plants. In July of 2021, scientists in Japan announced that a species of freshwater algae has three sexes: male, female, and bisexual. All three sexes can pair up with any of the others to reproduce and their offspring may be male, female, or bisexual at random.

Even though the algae has been known to science for a long time, no one realized it has three sexes because most of the time, algae reproduces by cloning itself. The research team thinks that a lot of algae species may have three sexes but researchers just haven’t been looking for it.

Yes, I realize that was a weird place to start, but it’s also fascinating! It’s also not even nearly as complicated as a protozoan called Tetrahymena thermophila, which has seven sexes.

Let’s look at a bird next, the penguin. You’ve probably heard of the book And Tango Makes Three, about two male penguins who adopt an egg and raise the baby chick together. For some reason some people get so angry at those penguins! Never trust someone who doesn’t like baby penguins, and never trust someone who thinks animals should act like humans. The events in the book are based on a true story, where two male chinstrap penguins in New York’s Central Park Zoo formed a pair bond and tried to hatch a rock, although they also tried to steal eggs from the other penguins. A zookeeper gave the pair an extra penguin egg to hatch instead.

The most interesting thing about the story is that same-sex couples are common among penguins, in both captivity and in the wild, among both males and females. Since penguins sometimes lay two eggs but most species can only take care of one chick properly, zookeepers often give the extra eggs to same-sex penguin pairs. The adoptive parents are happy to raise a baby together and the baby is more likely to survive and be healthy. Occasionally a same-sex penguin couple will adopt an egg abandoned by its parents.

If you remember episode 263 a few months ago, where we talked about animals that mate for life, you may remember the Laysan albatross. In that episode we learned about a specific Laysan albatross named Wisdom, the oldest wild bird in the world as far as we know. While I was researching Wisdom, I learned something marvelous. As many as 30% of all Laysan albatross pairs are both females. Sometimes one of the females will mate with a male and lay a fertilized egg, and then both females raise the baby as a couple. Sometimes one of the females lays an unfertilized egg that doesn’t hatch. There are many more Laysan albatross females than males, which may be the reason why females form pairs, but it’s perfectly normal behavior. It’s also been a real help to conservationists. Sometimes an albatross pair will nest in an area that’s not safe, like on an airfield. Instead of leaving the egg to be smashed by an airplane, conservationists take the fertilized egg from the unsafe nest and use it to replace the unfertilized egg of a female pair. The egg is safe and the chick has adoptive parents who raise it as their own.

Many other birds develop same-sex pairs too. This is especially common in the black swan, where up to a quarter of pairs are both male. One or both of the males will mate with a female, but after she lays her eggs the males take care of them and the cygnets after they hatch. Cygnets raised by two dads are much more likely to survive than cygnets raised by one mom and one dad. The males are stronger and more aggressive, so they can defend the nest and babies more effectively.

Birds aren’t the only animals that form same-sex pair bonds. Many mammals do too. It’s been documented in the wild in lions, elephants, gorillas, bonobos, dolphins, and many more. In species that don’t typically form pair bonds, homosexual behavior is still pretty common. It’s so common among domestic sheep that shepherds have to take into account the fact that up to 10% of rams prefer to mate with other rams instead of with ewes. Some rams show attraction to both males and females. This happens in wild sheep too, where rams may court other rams the same way they court ewes. Some ewes also show homosexual behavior.

The New Mexico whiptail is a lizard that lives in parts of the southwestern United States and northern Mexico. It can grow over nine inches long, or 23 cm, and is black or brown with yellow racing stripes. It eats insects and is an active, slender lizard that’s common throughout its range. And every single New Mexico whiptail lizard is a female.

The lizards reproduce by a process called parthenogenesis. That basically means an animal reproduces asexually without needing to have its eggs fertilized. The lizards do mate, though, but not with males. Females practice mating behaviors with each other, which researchers think causes a hormone change that allows eggs to develop. Females who don’t mate don’t develop eggs.

Female birds can sometimes reproduce asexually too. It’s been documented in turkeys, chickens, pigeons, finches, and even condors. A study published in late 2021 detailed two instances of parthenogenesis in California condors in a captive breeding program. In both cases the females were housed with their male mates, and in both cases the pairs had produced offspring together before. But in both cases, for some reason the females laid eggs that hatched into chicks that were genetically identical to the mothers. It’s possible parthenogenesis is even more common in birds than researchers thought.

In many species of reptile, whether a baby is a male or female depends completely on how warm its egg gets during incubation. For example, the American alligator. The mother gator builds a nest of plant material and lays her eggs in it. As the plant material decays, it releases heat that keeps the eggs warm. How much heat is generated depends on where the mother alligator builds her nest and what plants she uses, which in turns affects the eggs. If the temperature in the nest is under 86 degrees Fahrenheit, or 30 Celsius, during the first few weeks of incubation, most or all of the eggs will hatch into females. If the temperature is 93 F or 34 C, most or all of the eggs will hatch into males. If the temperature is between the two extremes, there will be a mix of males and females, although usually more females.

Because climate change has caused an overall increase in temperatures across the world, some already vulnerable reptile populations, especially sea turtles, are hatching almost all males. Conservationists have to dig up the eggs and incubate them at a cooler temperature in captivity, then release the babies into the ocean when they hatch.

Other animals change from male to female or vice versa, depending on circumstances. The clownfish, for example. Clownfish start out life as males but as they grow up, most become females, although only the dominant pair in a colony actually reproduces. Clownfish live in colonies led by the largest, most aggressive female, with the largest, most aggressive male in the group as her mate. If something happens to her, her former mate takes her place, becoming a female in the process. The largest juvenile male then becomes her mate and remains male even though he puts on a growth spurt to mature quickly. If Finding Nemo was scientifically accurate, it would have been a much different movie.

Another group of fish that live around reefs are wrasses, which includes the famous cleaner fish that cleans parasites and dead tissue off of larger fish. Wrasses hatch into both males and females, but the males aren’t the same type of males that can breed. Those develop later. When the dominant breeding male of the group dies, the largest female or the largest non-breeding male then develops into a breeding male. But sometimes a non-breeding male will develop into a female instead.

The term for an animal that changes sex as part of its natural growth process is sequential hermaphroditism. It’s common in fish and crustaceans in particular. Other animals have the reproductive organs of both a male and a female, especially many species of snail, slug, earthworm, sea slug, and some fish. We talked about the mangrove killifish in episode 133, and in that episode I said it was the only known vertebrate hermaphrodite. That’s actually not accurate, although I was close. It’s the only known vertebrate hermaphrodite that can self-fertilize. Almost all mangrove killifish are females, although they also produce sperm to fertilize their own eggs. The eggs hatch into little clones of the mother.

We’ve talked about seahorses before too, especially in episode 130. Seahorse pairs form bonds that last throughout the breeding season. The pair participate in courtship dances and spend most of their time together. When the eggs are ready, the female deposits them in a special brood pouch in the male’s belly, where he fertilizes them. They then embed themselves in the spongy wall of the brood pouch and are nourished not only by the yolk sacs in the eggs, but by the male, who secretes nutrients in the brood pouch. So basically the male is pregnant. The female visits him every day to check on him, usually in the mornings. When the eggs hatch after a few weeks, the male expels the babies from his pouch and they swim away, because when they hatch they are perfectly formed teeny-tiny miniature seahorses.

Let’s finish with a little songbird that’s common throughout eastern North America, the white-throated sparrow. It has a white patch on its throat and a bright yellow spot between the eye and the bill. There are two color morphs, one with black and white stripes on its head, one with brown and tan stripes on its head. Both males and females have these head stripes. The male sings a pretty song that sounds like this:

[white-throated sparrow call]

A 30-year study into white-throated sparrow genetics has revealed some amazing things. The color morphs are due to a genetic difference that affects a lot more than just feather colors. Black morph males are better singers, but they don’t guard their territory as well or take care of their babies as well as brown morphs do. They also aren’t as faithful to their mates as the brown morph males, which are fully monogamous and are diligent about helping take care of their babies. Despite their differences in raising offspring, both morphs are equally successful and equally common.

All this seems to be no big deal on the surface, maybe just pointing to the possibility that the species is in the process of splitting into two species or subspecies. But that’s not the case.

Black morphs always mate with brown morphs. A black morph male will always have a brown morph mate, and vice versa. Genetically, the two morphs are incredibly different—so different, in fact, that they seem to be developing a fully different set of sex chromosomes. In other words, there are male and female black morph birds and male and female brown morph birds that are totally different genetically, but still members of the same species that only ever breed with each other. In essence, the white-throated sparrow has four sexes.

Usually I try to end episodes with something funny, but today I’m going to speak directly to you. Yes, you! If you’re listening to this or reading the transcript, my words are meant just for you. You are an amazing person and I love you. You deserve to be happy. If anyone has ever told you there’s something wrong with the way you are, or the way you wish you were or want to be, they’re wrong. They probably also don’t like penguins, so you don’t have to believe anything they say. If you’ve ever read books by Terry Pratchett, you may recognize this quote: “Be yourself, as hard as you can.”

You can find Strange Animals Podcast at strangeanimalspodcast.blubrry.net. That’s blueberry without any E’s. If you have questions, comments, or suggestions for future episodes, email us at strangeanimalspodcast@gmail.com. If you like the podcast and want to help us out, leave us a rating and review on Apple Podcasts or Podchaser, or just tell a friend. We also have a Patreon at patreon.com/strangeanimalspodcast if you’d like to support us for as little as one dollar a month and get monthly bonus episodes.

Thanks for listening!

Episode 129: The blurry line between animals and plants

This week we’re looking at some really strange animals…or are they plants? Or both? We’ll start with the sea anemone, then learn about a sea slug that photosynthesizes like a plant (sort of), then learn a little about whether algae is a plant or an animal…and then we’re off and running through the wild world of carnivorous plants–including some carnivorous plants of mystery!

Thanks to Joshua Hobbs of A Degree in Nonsense for the suggestion, and to Simon for the article link I’ve already managed to lose!

A sea anemone and some actual anemones. Usually pretty easy to tell apart:

The sea onion looks so much like an onion I can’t even stand it. This is an ANIMAL, y’all!

Venus flytrap sea anemone and actual Venus flytrap. It’s usually pretty easy to tell these two apart too.


The eastern emerald elysia, a sea slug that looks and acts like a leaf:

Giant kelp. Not a plant. Actually gigantic algae. Algae is neither a plant nor an animal:

The corpse flower (left) and the corpse lily (right). Both smell like UGH and both are extremely BIG:

The pitcher plant can grow very big:

Maybe don’t go near trees with a lot of skulls around them:

Puya chilensis (the clumps in the foreground are its leaves; the spikes in the background are its flower spikes):

Show transcript:

Welcome to Strange Animals Podcast. I’m your host, Kate Shaw.

This week we’re going to explore the sometimes blurry line between animals and plants. Joshua Hobbs of a great new podcast A Degree in Nonsense suggested a type of carrion flower that smells like rotting flesh to attract insects, and friend of the pod Simon sent me an article about carnivorous plants. Our very first Patreon bonus episode was actually about carnivorous plants, so I’ve expanded on that episode and added lots of interesting new content. Buckle up, folks, because we’re going to cover a whole lot of ground today!

Oh, and Joshua also says, quote, “I never had a pet growing up, but recently gained an interest in animals. Now after getting into your podcast and animal YouTube channels, I’ve got my first pet, a little corn snake named Arnold!” So welcome to podcasting, Joshua and Arnold!

Let’s start by looking at an animal that resembles a plant. The sea anemone looks so much like a plant that it was named after an actual flower, the anemone, but the sea anemone is related to jellyfish. Most sea anemones attach to a rock or other hard surface most of their lives and don’t move much, although they can creep along very slowly—so slowly that snails are racecar drivers in comparison. Many species have a body shaped like a plant stem and colorful tentacles that resemble flower petals. But those tentacles aren’t just to look pretty. The sea anemone uses them to catch prey. The tentacles are lined with stinging cells that contain venom, just like many jellyfish have. The venom contains neurotoxins that paralyzes a fish or other small animal so that the sea anemone can eat it.

So how does something that looks like a plant eat a fish?

The sea anemone has an interesting body plan. What looks like the stem of a plant is called the column, and in some species it’s thin and delicate while in other species it’s thick like a tree trunk. It sticks to its rock or whatever with an adhesive foot called a basal disc, and on the other end of the column is what’s called the oral disc. Oral means mouth. The actual mouth is in the middle of the oral disc, surrounded by tentacles. The mouth is usually shaped like a slit, which if you think about it is sort of how people’s mouths are too. The digestive system is inside the column. But there is no other opening into the body. The mouth is it. So like jellyfish, the mouth takes in food but it also expels waste, so, you know, not precisely a mouth like ours. When the sea anemone wants to eat, it uses its tentacles to push the food into its mouth.

You know the movie Finding Nemo? Nemo and his dad are clownfish, which aren’t affected by sea anemone venom. Clownfish hide among sea anemone tentacles so predators won’t bother them. In return, the sea anemone eats the clownfish’s poops. I wish I were making that up.

If a sea anemone feels threatened, many species can not only suck its tentacles into its mouth, it can retract the whole mouth inside its body. Basically, it can swallow its own mouth. A sea anemone called the sea onion retracts its tentacles and inflates its column so that it looks like an actual onion. The sea onion lives in a burrow it digs very slowly into the sediment at the bottom of the ocean, with just its tentacles sticking out.

Most sea anemones live in relatively shallow water, but there are some deep-sea species. The Venus flytrap sea anemone has been found at 5,000 feet deep, or over 1,500 meters. At first glance looks like a Venus flytrap plant, thus the name. Its body is a long, usually slender column that widens into a big oral disc on top that’s fringed with short tentacles. It mostly eats detritus that drifts down from above, which it filters from the water with its tentacles, although if a living creature strays into its tentacles it’ll eat it too.

That brings us to the actual Venus flytrap. It’s a plant that eats insects and spiders, especially crawling insects like ants and beetles. The ends of its leaves are modified into lobes that look a little like flowers because the insides of the lobes are a cheerful red while the edges and the hair-like cilia are yellow. When a bug touches the receptors inside the lobes it closes tightly. If the insect continues to move around inside, stimulating the receptors even more, the lobes seal and form a sort of stomach. Digestive enzymes are secreted and about ten days later the lobes reopen and there’s nothing left of the insect but its empty exoskeleton.

If bugs made movies, this would be the subject of every single bug horror film.

The Venus flyptrap is only found in one small part of the world, the boggy areas surrounding Wilmington, North Carolina in the United States. They’re so in demand that the plant is almost extinct in the wild due to idiots digging them up to sell. But Venus flytraps really aren’t that difficult to grow, you just have to make sure the soil you use is deficient in nitrogen and phosphorus. So you can buy Venus flytraps that were grown ethically instead of dug up from the wild. As of 2014 digging up a Venus flytrap is a felony in North Carolina.

Before we go on to talk about some other carnivorous plants, let’s discuss an animal that acts like a plant. It’s a sea slug called the eastern emerald elysia and it lives along the east coast of North America in shallow water. Even though it’s a sea slug, it will also live in fresh water. It grows to about an inch long, or 3 cm, and is green. It’s green because it photosynthesizes like a plant…sort of.

The sea slug eats algae, but it doesn’t fully digest the algae it eats. Its digestive system retains the algae’s chloroplasts, which are the parts of a plant cell that convert sunlight into energy, which is what photosynthesis is. The sea slug keeps the chloroplasts in its digestive system and keeps them alive for months, living off the energy the chloroplasts produce. Researchers aren’t sure how the sea slugs keep the chloroplasts alive.

This is pretty amazing, but it’s not the only sea slug that photosynthesizes in this way. The blue dragon sea slug, that lives along coasts around the Indo-Pacific Ocean, doesn’t just keep chloroplasts alive to produce chlorophyll energy. It gets even more complicated about it. The blue dragon eats tiny animals called hydrozoa, which are related to jellyfish and include the freshwater hydra, although since the blue dragon only lives in the ocean it doesn’t actually eat the hydra. The blue dragon eats hydrozoa that themselves contain a type of microscopic algae that live in a lot of animals, like giant clams, some jellyfish, even some sea anemones, and exchange energy from photosynthesis for protection from predators by living in or on its host. So when the blue dragon eats the hydrozoa containing these algae, it retains the algae and keep them alive. So basically it gets to eat its prey and steals its prey’s symbiotic algae.

Speaking of algae, most algae photosynthesize, and in fact many seaweeds, like kelp, aren’t plants but are giant plant-like algae. But algae, technically, aren’t plants. They’re not animals either. Researchers and taxonomists are still working out the ways various algae are related to each other and to other organisms, but most algae are considered more closely related to plants than to animals without actually being plants. They’re usually grouped with plants above the kingdom level of taxonomy, but since at that level animals like humans and fish and worms and mosquitoes are grouped with fungi, this is a really broad category.

And that brings us, in a roundabout way, to the rotten meat smelling plant suggested by Joshua. There are several plants that attract flies and other insects to pollinate their flowers by smelling of rotten meat. Some of these have freakishly large flowers, like the corpse flower. It lives in rainforests in parts of Sumatra and Java and is actually related to the calla lily. It’s a weird-shaped plant and hard to describe. You know how a calla lily has a pretty white petal that wraps around a yellow spike thing? The corpse flower is like that, only it can be ten feet high, or 3 meters. The thing that looks like a petal is actually a specialized leaf and the yellow spike is called the spadix. The yellow part is made up of tiny flowers, so a calla lily isn’t a single flower, it’s lots of flowers that look like one. Well, the corpse flower is like that, although its flowers are actually only at the bottom of the spadix. The petal-like leaf is dark red inside. The top of the spadix is where the rotten smell comes from, and it’s incredibly stinky—something like rotting meat and rotting fish with some extra smell like dung on top of it. It releases this stink mostly in the evenings and the top of the spadix actually grows hot to better disperse the smell.

The largest single flower in the world is sometimes called the corpse lily and it can grow over three feet across, or about a meter. It’s dark reddish-brown with white speckles and five fleshy petals, which look like meat. It smells like rotting meat too. Flies are attracted to the flower, which pollinate it. The flower can take an entire year to develop but only blooms for a few days. If it’s successfully pollinated, the flower produces a round fruit full of seeds that are eaten by tree shrews, which later poop the seeds out and spread them.

But the corpse lily isn’t any ordinary plant. It doesn’t even have roots or a stem or leaves. All it has is the flower, which grows directly from the roots of the corpse lily’s host plant. That’s right, the corpse lily is a parasitic plant, but it’s no ordinary parasite. It grows not on or around its host plant, but inside it. The host plant is a type of vine called Tetrastigma, related to the grape vine. When a tree shrew poops out a seed, the seed germinates and if it happens to germinate on a Tetrastigma vine, it develops tiny threadlike filaments that penetrate the vine and grow inside it.

The corpse lily lives only in the rainforests of Borneo and Sumatra, and it’s rare and getting rarer since so much of the rainforests in those areas are being destroyed. Fortunately, the corpse lily is actually a tourist attraction since it’s so rare, so spectacular, and so stinky. People who have corpse lilies growing in their yard sometimes protect the flower buds from harm and charge tourists to come look at them, which helps the people of the area and the plants.

There are literally hundreds of carnivorous plant species, with carnivorous habits evolving probably nine different times among plants that aren’t related. Different species use different methods to catch insects. For instance, the pitcher plant has modified leaf that forms a slippery-sided pitcher filled with nectar-like liquid. When an insect crawls down to drink the liquid, it falls in. The insect drowns and is dissolved and digested.

Some carnivorous plants have leaves lined with sticky mucilage, which traps small insects. The sundew has tentacles lined with hair-like structures beaded with mucilage. When an insect becomes trapped in the mucilage, the tentacles bend toward the insect and stick onto it, sometimes quite quickly—in seconds, or in at least one species, a fraction of a second. Generally you don’t think of plants as moving that fast.

Almost all known carnivorous plants are pretty small. The largest are pitcher plants. Two species of big pitcher plants grow in the mountains of the Philippines. Attenborough’s pitcher plant was discovered in 2007 and described in 2009, and is a shrub with pitchers that can hold nearly two liters of fluid. An even bigger pitcher plant was discovered in 2010. But the biggest pitcher plant known is from a couple of mountains in Malaysian Borneo called Nepenthes rajah. It’s been known to science since 1858 and its pitchers can hold over 2 ½ liters of digestive fluid. The biggest pitcher ever measured was over 16 inches tall, or about 41 cm, and the plant itself is a messy sort of vine that can grow nearly 20 feet long, or 6 meters. Mostly pitcher plants just attract insects, but these giant ones also trap frogs, lizards, rats and other small mammals, and even birds.

There’s always the chance that even bigger pitcher plants have yet to be discovered by science, although probably not much bigger than the ones we do know about. The larger an animal, the more likely it is to damage the pitcher while trying to escape. Insects and the occasional small animal are fine, anything bigger than that could just bust through the leaf.

But there have long been rumors about plants that eat much larger animals, even humans. In the 1870s, a German explorer named Karl Liche claimed he’d witnessed a tribe in Madagascar sacrifice a woman to a carnivorous tree. His account is not very believable. He describes the tree as about eight feet high with a thick trunk. A coat of leaves hang down from the top of the tree, leaves about twelve feet long with thorns. At their base is a flower-like receptacle with sweet liquid inside, with six ever-moving tendrils stretching up from it. When the sacrificial woman was made to drink the liquid, the tendrils wrapped around her and the tree’s long leaves folded up and over her. After ten days, the leaves relaxed, leaving nothing but a bleached skull at the base of the tree.

Later expeditions to Madagascar never found any plant that resembled Liche’s. In fact, everyone who’s researched Liche, the tribe he mentioned, and the tree in question haven’t found any evidence that any of them ever existed. It turns out that the account was a hoax from start to finish, written by a reporter named Edmund Spencer for a newspaper called the New York World in 1874.

A 1924 book called Madagascar: Land of the Man-Eating Tree describes a more realistic-sounding carnivorous plant that was supposed to be from India. Its blossoms have a pungent smell that attracts mice and sometimes large insects, which crawl into a hole in the blossom that turns out to be a bristly trap. This sounds a little like the corkscrew plant that lives in wet areas of Africa and Central and South America. It has ordinary leaves aboveground but modified leaves that grow underground. The modified leaves are traps with a stalk lined with hairs pointing in one direction. Tiny water animals, especially single-celled protozoans, stray into the leaves but can’t get out because of the hairs. They’re digested and absorbed by the leaves. But there are no known corkscrew plants or anything like them that trap larger animals or animals that live aboveground.

An 1892 article describes a friend of a friend of a friend’s encounter with a tangle of thin, willow-branch-like vines covered with an incredibly sticky gum. This was supposed to have happened in Nicaragua in Central America. A Mr. Dunstan’s dog was ensnared by the plant but was rescued by Dunstan, who managed to cut the vines with his knife. In the process, both man and dog suffered blistered injuries from the plant, as though it had been trying to suck their blood. The article also says that natives of the area say the plant will reduce a lump of meat to a dried husk in only five minutes.

From these sorts of factual-seeming accounts, it’s a short step to plants of folklore like the Japanese Jubokko tree that grows on battlefields and drinks human blood. It captures people who pass too close to it, sticks its branches into them, and sucks out their blood. If someone cuts into the tree’s bark, blood comes out instead of sap.

Another carnivorous plant was supposedly encountered by a French explorer in 1933 in the jungles of southern Mexico. He doesn’t describe the plant in his 1934 magazine article, just says it’s enormous, but he does say that when a bird alighted on one of its leaves, the leaf closed and pierced the bird with long thorns. The expedition’s guide called it a vampire plant.

A similar story supposedly of a plant found in South America and Central Africa is of a short tree with barbed leaves that grow along the ground, and if an animal or bird steps on the leaves they twine around it and stab it to death, then squeeze the blood out to absorb.

There may actually be a real plant that these stories are based on. It’s called the Puya chilensis and it lives in Chile in South America, on dry hillsides of the Andes Mountains near the ocean. It’s an evergreen plant that only flowers after it’s some 20 years old, with a flower spike that can grow over 6 ½ feet high, or up to 2 meters. The flowers are pollinated by birds. But its leaves are long, edged with hooked spines, and grow in clumps that can be up to six feet wide, or nearly two meters.

Those hooks along the leaves give the plant its other name, the sheep-killer. Sheep and other animals can become entangled in the leaves, which are so tough that locals use the leaf’s fibers to make rope. If the animal can’t escape, it dies and its body decomposes, adding nutrients to the soil around the plant. Yum.

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