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Theft: Better Than Sex (Bdelloid Rotifers)

(Via: Wikimedia Commons, Image by: Diego Fontaneto)

Common Name: Bdelloid Rotifers

A.K.A.: Families of Order Bdelloida

Vital Stats:

  • Around 360 asexual species
  • All species likely descended from the same ancestor
  • Common ancestor lived 50-100 million years ago

Found: Fresh water bodies of any size, on every continent, including Antarctica

It Does What?!

Here’s a creature that truly exhibits questionable evolution- as in, the kind that tends to make you go extinct in a hurry. Bdelloid rotifers (the ‘B’ is silent) are microscopic animals found in all kinds of moist, freshwater habitats- puddles, ponds, mossy areas; you name it, they’re probably there. What’s so unusual about these guys is that they’re entirely asexual, and have been for a very, very long time. In fact, bdelloid rotifers are all female, a consequence of how they reproduce.

Don’t drink pond water.
(Via: TopNews.in)

Now, asexual reproduction isn’t so uncommon. If you look at a field of dandelions, chances are, they’re all clones derived from asexual reproduction in a single common ancestor- no second parent needed. Even such advanced creatures as komodo dragons do this periodically- a baby dragon is formed from an unfertilized egg inside the mother. What differentiates bdelloid rotifers from other asexual reproducers is that it’s all they’ve done for the last 50 million years or more. Outside of our friends the rotifers, a species must either have sex from time to time, or face extinction.

Why? Because sex solves two major problems in life (your individual results may vary..). First, it weeds out errors which tend to accumulate in DNA over time. Unlike asexuals, which pass on a copy of a copy of a copy (etc.) of their genes, sperm and egg cells contain DNA which has been mixed and matched via a process called meiosis. The gist of this is that an organism can procreate without necessarily passing on any genetic errors it may have to the next generation. Second, this same process of mixing and matching creates new combinations of DNA sequences, which in turn create the natural variation between individuals that evolution can select for or against.

Not the most visually interesting creatures, these rotifers…
(Via: Natural History Museum)

For example, a genetic combination which caused a polar bear to be born with a white nose would be selected for, since it would make a more effective camouflage for hunting. On the other hand, a combination which gave polar bears big black patches on their fur would be selected against, because they’d have a harder time hunting and would therefore starve more often. Asexuals, however, can neither quickly generate useful new combinations, nor purge their populations of harmful mutations.

So on the surface, it comes as a surprise to biologists that bdelloid rotifers have been able to survive for such an epic amount of time with no sex (in addition to the absence of males, genetic tests are able to show that meiosis hasn’t occurred). However, the rotifers have two impressive ways of dealing with this. First, when times get tough, they already have a pretty good defence mechanism worked out- they just dry up. The rotifer dehydrates itself and forms a dormant cyst in which it can remain in this state until conditions improve. This is called anhydrobiosis.

…but what do you expect from sexless pond scum?
(Via: SpaceTravel.com)

Second, and more importantly, they steal genes. This is the true secret to the successful asexual lifestyle. When a rotifer emerges from dormancy and needs to patch itself up, it’s actually able to incorporate random genetic material from its environment into its own genome. A nearby bacterium, some fungus, a passing bit of rotting leaf? All fair game, apparently. Researchers have found genes from each of these three groups in the rotifer genome. Incorporating these new bits of sequence seems to give rotifers the variation they need to develop new traits and stay off the evolutionary chopping block. In fact, given the success of the bdelloid rotifers – they’ve evolved into over 300 species since giving up sex – and the ease of asexual procreation – no need to find a partner – an argument could be made that when it comes to new genes, theft really is better than sex.

Says Who?

  • Gladyshev et al. (2008) Science 320(5880): 1210-1213
  • Harvard Magazine, Nov.-Dec. 2000 “An Evolutionary Scandal”
  • Welch & Meselson (2000) Science 288(5469): 1211-1215
  • Wilson & Sherman (2010) Science 327(5965): 574-576
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EVOLUTION TAG TEAM, Part 3: Coral Polyps & the Garden Within

The third in an ongoing series of biology’s greatest duos. (Check out Parts One and Two)

(Via: Wikimedia Commons)

Common Name: Coral Polyps

  • A.K.A.: Class Anthozoa, Subclass Hexacorallia

Common Name: Coral Algae

  • A.K.A.: Genus Symbiodinium

Vital Stats:

  • Polyps grow to a length of only a few centimetres, depending on species
  • Coral can grow outward at a rate of up to 10cm (4”) per year
  • The Great Barrier Reef stretches over 2000km (1243 mi) and can be seen from space

Found: Various coastal areas; largest reefs surrounding Australia, Oceania, and the Caribbean

It Does What?!

If you’ve ever been told that coral reefs are alive, then looked at one and felt a bit sceptical that this chuck of colourful rock could be a living thing… well, good for you, because you’re actually mostly right. The vast majority of the volume of a coral reef is, in fact, nonliving inorganic mineral (calcium carbonate, specifically). The amazing thing about coral isn’t so much what it’s made of, but what’s going on on the surface. You see, that oddly-shaped, porous rock is actually a communal exoskeleton produced and excreted over time by hundreds of thousands of polyps living in the tiny, cup-shaped depressions on the surface.

“Breaded, with a side of chips, please.”
(Via: Wikimedia Commons)

Looking like tiny jellyfish (and belonging to the same phylum), the polyps hide in the stony sanctuary they’ve made, letting only their tentacles project. These tentacles are tipped with stinging cells which can inject a powerful venom into any prey foolish enough to swim within reach. This prey can range in size from microscopic plankton to small fish. That’s right, coral eats fish. Watch where you stick your toes.

So where does the ‘duo’ part come in? Despite their ability to snatch passing sea creatures and eat them, coral polyps actually get only a small part of their caloric intake this way. Impressively, these guys managed to find a diet that requires even less effort than just reaching out and grabbing stuff. Who needs movement when you can just photosynthesize, like plants do? The polyps have developed a symbiosis with a type of single-celled alga (called zooxanthellae) that allows them to do just that.

The algae start out as free-living cells drifting through the water. They are eaten by the coral polyp, but instead of being digested, they are able to enter the cells lining its digestive tract. Since the polyps are transparent to begin with, all they have to do is expose their bodies to sunlight in order to allow the algae to produce sugars by photosynthesis (this is why reefs form in relatively shallow waters). The majority of the sugars made by the symbiont are then absorbed by the polyp.

And what do the algae get out of this arrangement? A couple of things. First, they get a safe place to live, and won’t get eaten by something that can digest them. Second, they get nutrients, in the form of carbon dioxide and nitrogen compounds, both natural waste products of the polyp’s metabolism. Still, sometimes as much as 30% of the cells in a polyp are algal cells, and this puts a stain on the host’s physiology.

“I’ve just got a lot going on right now.”
(Via: Wikimedia Commons)

Maybe you’ve heard of “coral bleaching” as one of the symptoms of pollution around reefs. Bleaching happens when additional stresses (like pollution) get to be a bit too much for the polyps to handle. They can’t change the water purity, so instead, they offload the stressor they can control- the algae. Getting rid of the photosynthetic cells also gets rid of much of the characteristic colour of the reef, hence the term ‘bleaching’. In the short term, this is a smart move. It increases the polyp’s chance of survival during brief crises, and new algae can always be taken on when the host is ready. The real problems start when the environmental stress persists, and the polyp never takes on new algae. Eventually, it can’t sustain itself and dies, as those in a tenth of the world’s reefs already have. At least there’s still hope for these areas; if conditions improve, new colonies can be formed using the old reef as a foundation. The Great Barrier Reef, for example, is considered to be between 6000 and 8000 years old. However, the modern structure has developed atop an older, dead reef system, thought to be over half a million years old. Time enough for us to clean up our act, maybe.

[Fun Fact: Coral polyps only reproduce sexually to start new colonies. Within a single piece of coral, all the polyps are genetically identical clones, produced by polyps dividing in half and then re-growing their lost tissues.]

Says Who?

  • CoRIS- Coral Reef Information System
  • Fransolet et al. (2012) Journal of Experimental Marine Biology and Ecology 420-421:1-7
  • Piper (2007) Extraordinary Animals. Greenwood Press: Westport, Connecticut.
  • Wooldridge (2010) BioEssays 32(7):615-625

    The little-known “Lady Gaga Coral”
    (Via: Wikimedia Commons)
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Thank a Horseshoe Crab

(Via: reefguide.org)

Common Name: Horseshoe Crab

A.K.A.: Family Limulidae

Vital Stats:

  • Four extant species of horseshoe crab in three genera (Limulus, Carcinoscorpius, and Tachypleus)
  • Females are larger than males, and can reach up to 60cm (24”) long in some species
  • Believed to live between 20 and 40 years

Found: Coastal waters of southeast Asia, Oceania, and eastern North America

It Does What?!

Like the platypus and the lungfish, horseshoe crabs are what biologists refer to as “living fossils,” meaning their basic form has gone essentially unchanged for many millions of years. In the case of horseshoe crabs, fossils as old as 445 million years have been found that are quite similar to the extant species of today.

Despite their common name, the Limulidae aren’t true crabs. They’re arthropods, like crabs, but are actually more closely related to spiders and scorpions. In fact, beneath that tough shell, they do look quite spider-like. If spiders had tails, that is.

Basically a tarantula in combat gear.
(Via: Wikimedia Commons)

Horseshoe crabs live in shallow coastal waters, feeding off worms and molluscs from the ocean floor. They are able to feed in near complete darkness at night due to a remarkable visual system. The creatures have three different types of eyes – compound, median, and rudimentary – located to both sides and to the front of their shell. What’s more, their compound eyes become a million times more sensitive to light at night than they are during the day. Since that’s roughly how much less light they have to work with at night, the crabs are able to see equally well at night and during the day.

Most people who have observed horseshoe crabs know them from their unusual breeding habits. Each spring and early summer, male crabs will search out a mate and attach themselves to the female’s shell using a special modified leg. Then, during the highest tides of the year, usually at night, the females crawl up onto shore by the hundreds, carrying their male cargo. Having picked a spot that’s moist, but not so low as to be washed away with the tide, they dig a nest into the sand and lay their eggs. The attached males get first dibs at fertilising the pre-laid eggs, but must share the task with numerous mate-less onlookers who rush in to get their shot at fatherhood as well (crabs are so uncouth). Since eggs number in the tens of thousands per female, many will probably be successful. Most of these thousands of eggs, however, will become food for migratory birds, who appreciate the extra protein snack on their long journeys. After a month or so, the uneaten eggs will hatch into larvae, which remain on the beach in groups for a couple of weeks before moulting into juvenile horseshoe crabs and finally moving into the water.

Horseshoe crabs, making more horseshoe crabs.
(Via: Wikimedia Commons)

Now you might be thinking, “That’s all well and good, but what can horseshoe crabs do for me?” Well, as it turns out, these creatures are some of the most prolific blood donors on Earth (whether they like it or not). Like our friend Mr. Spock, horseshoe crabs have copper-based blood, rather than the iron-based concoction favoured by humans. They are literally blue-blooded. And instead of white blood cells to fight off infection, they have amebocytes. These amebocytes are so valuable in detecting certain types of bacterial infections in humans that a quart of horseshoe crab blood is worth approximately $15,000 US. Crabs are caught, transported to a lab, and drained of about 30% of their blood before being released. The company behind this 50 million dollar per year industry states that only about 3% of the quarter million crabs die from the procedure annually, while other studies have found the number to be nearer to 15% (read more about it here). Knowing who’s right may become very important, as horseshoe crab populations are declining worldwide, additionally affecting the migratory birds that feed on their eggs. Either way, next time you survive an E. coli infection, thank a horseshoe crab.

No, no… we don’t mind. Really.
(Via: TYWKIWDBI)

[Fun Fact: Horseshoe crabs are thought to be the closest living relative of the extinct trilobite.]

[Also, here’s a cool video of (who else?) Sir David Attenborough explaining the mating habits of horseshoe crabs.]

Says Who?

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Randomly Assembled and Surprisingly Dangerous: The Platypus

(Via: National Geographic)

Common Name: The Duck-Billed Platypus

A.K.A.: Ornithorhynchus anatinus

Vital Stats:

  • Only species of Family Ornithorhynchidae
  • Males average 50cm (20”) long, females 43cm (17”)
  • Weigh between 0.7 and 2.4kg (1.5 – 5.3lbs.)
  • Body temperature of 32 degrees Celcius; five degrees lower than placental mammals
  • Live up to 17 years in captivity
  • Eat freshwater crustaceans, worms, and insect larvae

Found: Eastern Australia and Tasmania

It Does What?!

Besides looking like it was assembled from spare parts? We’ve all seen pictures of platypuses (yes, “platypuses”, not “platypi”) before, and everyone knows what total oddities they are: the duck-like bill, the beaver-esque tail, the fact that they lay eggs, despite being mammals; but behind these weird traits lie… even more weird traits! So let’s take a moment to appreciate the lesser-known eccentricities of the platypus, shall we?

First off, these cuddly looking freaks are actually dangerous. Male platypuses have a spur on each hind foot which is filled with a venom powerful enough to kill a large dog. While it isn’t enough to take out a human, it does cause severe, incapacitating pain whose after-effects can last for months. One of only a very few venomous mammals, the male’s venom production increases during the breeding season, suggesting its purpose may lie in competition with other males.

Why your dog and your platypus shouldn’t play together.
(By Jason Edwards, via: How Stuff Works)

And speaking of breeding, reproduction in platypuses isn’t exactly ‘mammal standard’, either. Unlike all other mammals, which have two sex chromosomes (X and Y; XX for females, XY for males, with rare exceptions), the platypus has ten. Talk about evolutionary overkill. A male platypus has the pattern XYXYXYXYXY, while a female has ten Xs. Researchers have found that the actual genetic structure of these sex chromosomes is actually more similar to birds than mammals, although 80% of platypus genes are common to other mammals.

After this alphabet soup of chromosomes arranges itself, up to three fertilised eggs mature in utero for about four weeks; much longer than in most other egg-laying species (in birds, this may be only a day or two). Once laid, the eggs are only about the size of a thumbnail, and hatch in around ten days. While platypuses produce milk, they don’t actually have proper teats to suckle their babies- the fluid is released from pores in the skin. A small channel on the mother’s abdomen collects the milk, which is then lapped up by the young. Strangely, the babies are actually born with teeth, but lose them before adulthood. Such is the impracticality of platypus design…

Adorably impractical.
(Via: noahbrier.com)

Finally, let’s explore platypus hunting methods. Platypuses are the only mammals with the sixth sense of electroreception. Those leathery duck bills of theirs are actually precision receptors that can detect the electric fields created in the water by the contractions of muscles in their prey. Considering the prey in question is largely worms and insect larvae, we’re talking big-time sensitivity here. The bill is also very receptive to changes in pressure, so a movement in still water can be picked up in this way as well. Researchers have suggested that by interpreting the difference in arrival time of the pressure and electrical signals, the hunter may even be able to determine the distance of the prey. This would be especially useful, given that platypuses close both their eyes and ears when hunting. In fact, they won’t even eat underwater; captured food is stored in cheek pouches and brought to land to be consumed.

So there you have it. The platypus: even weirder than you thought.

[Fun Fact:The female platypus has two ovaries, but only the left one works.]

Intelligent Design’s Worst Nightmare
(Via: Animal Planet)

Says Who?

  • Brown (2008) Nature 453: 138-139
  • Grant & Fanning (2007) Platypus. CSIRO Publishing.
  • Graves (2008) Annual Review of Genetics 42: 565-586
  • Moyal (2002) Platypus: The Extraordinary Story of How a Curious Creature Baffled the World. Smithsonian Press.
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Death from Below! (The Purse-Web Spider)

(Via: Wikimedia Commons)

Common Name: Purse-Web Spiders

A.K.A.: Family Atypidae

Vital Stats:

  • The family contains three genera; Atypus, Calommata, and Sphodros
  • Females reach up to 30mm (1.2”) in length
  • Fangs can measure up to half the spider’s body length
  • Prey includes crickets, beetles, millipedes, ants, wasps, and other spiders
  • Web tubes measure up to half a metre (20”) from top to bottom

Found: Africa, temperate regions of North America, Europe, and Asia

It Does What?!

Imagine you’re a beetle, peacefully strolling along the forest floor, minding your own business, when suddenly, two enormous black spikes drive up out of the earth and impale you through the abdomen. As everything fades to black, your last beetle-ly thought is, “What the hell was that?!”

You have just become a tasty lunch for the purse-web spider.

So how does this work? Well, unlike most of the spiders we’re familiar with – those with small, pincer-like mouths that sit in webs all day – purse-webs are a type of primitive spider called a mygalomorph. In this group, the fangs are like a pair of large (relative to the spider) tusks that only move up and down; they don’t pinch, and this feature lends itself to some rather creative hunting methods.

Rather than constructing a flat, aerial web designed to have something fall into it, the purse-web spider spins what is essentially a silken tube-sock. The ‘foot’ of this sock lies along a slight depression in the ground, while the upper part lies vertically against a tree or rock (or, in some species, angles downward into the earth). The spider will then place bits of bark and lichen onto both parts of the web as camouflage. Over time, moss will actually begin to grow on the web, completing the disguise. All the spider needs to do now is wait, suspended from the ceiling of her underground lair, for some unwitting creature to walk over it. When this happens, she rushes to the source of the disturbance and spears her prey from below with her fangs before they realise what hit them (like this).

Invisible by spider standards, anyway.
(Via: Wikimedia Commons)

The spider will be vulnerable to larger predators if she ventures out into the open, so she simply cuts a slit in the web, drags her impaled prey inside, and seals up the hole again. Having sucked out their delicious insides, she then drops the dead husks out of the top of her sock like so much household garbage. In fact, researchers determined the diet of the purse-web spider by noting the various exoskeletons hanging from the outside of the web, having gotten caught on their way down. Apparently, all the dead bodies seemingly stuck to the side of a nearby tree aren’t much of a deterrent to other passersby.

So, since these spiders never leave their burrows, and kill anything that approaches, mating must be tricky, right? Right. The male is attracted to the female’s web by means of pheromones, and ventures out to find it. Once he locates the web, he must be very careful, tapping at the outside of the tube in a way that indicates he isn’t prey. Ultimately, though, whether he’s prey or not will be up to her. If the female inside isn’t yet mature or is already pregnant, she won’t hesitate to eat him when he attempts to enter the burrow. Researchers experimenting with placing male spiders in or near the webs of unreceptive females noted, essentially, that they run like hell as soon as they figure out what’s what. Research is amusing sometimes.

A male purse-web spider on what will be either the best or worst day of his life.
(Via: Florida Backyard Spiders)

But in the happy instances where the female is willing to mate, the male enters safely, and in fact continues to live with her for several months of domestic bliss before he dies naturally. And then she eats him anyway. Spiders are not sentimental creatures. Her eggs will take almost a year to hatch, and the young will stay with her for nearly another year after that, before striking out in the world to spin their own tube-sock of death.

Says Who?

  • Beatty (1986) Journal of Arachnology 14(1): 130-132
  • Coyle & Shear (1981) Journal of Arachnology 9: 317-326
  • Piper (2007) Extraordinary Animals: an encyclopedia of curious and unusual animals. Greenwood Press, Westport CT.
  • Schwendinger (1990) Zoologica Scripta 19(3): 353-366
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Anglerfish: Absorbing Ladies and their Freeloading Mates

(Via: Inglestic)

Common Name: Anglerfish

A.K.A.: Order Lophiiformes

Vital Stats:

  • Comprised of 322 species in 18 different families
  • Most range in size from that of a ping pong ball to that of a football
  • Some can reach over a metre in length and weigh 27kg (59lbs.)

Found: Throughout the world’s oceans, mostly in deeper regions

It Does What?!

The more dissimilar a creature’s habitat is to our own, the more dissimilar we have to expect its lifestyle to be, so when we plumb the pitch black, cold, high pressure depths of the ocean, we’re counting on some serious weirdness. The anglerfish goes above and beyond in this department.

First off, have you seen these things? They’re essentially a set of mobile fangs. And what’s with that thing hanging down off their heads? It’s all part of an efficient setup that allows the anglerfish to survive in an environment with minimal light and sparse prey. These fish are what biologists call “sit and wait” predators. In order to avoid expending precious energy, they hang motionless in the water, waiting for something edible and foolish to approach. The dangly piece is actually a lure, filled with bioluminescent (glowing) bacteria. Seeing the glow and thinking it might be food, curious creatures draw near and are quickly gobbled up by the anglerfish. That enormous mouth, combined with a flexible bone structure, allows the fish to swallow very large prey, relative to its own size.

Really… how unobservant must their prey be?
(Via: National Geographic)

Amazingly, the anglerfish’s horrifying appearance isn’t its most notably odd trait. Not even close. You see, all these characteristics we’ve discussed so far are only present in the female of the species. The male is a different creature entirely. Many times smaller than the female, you’d be hard pressed to immediately recognise a male anglerfish as even being part of the same species. In fact, researchers initially thought they were babies. Their adult form is only 6-10mm (0.24-0.39”) long in some species, placing male anglerfish among the smallest vertebrates on earth.

What’s more, they don’t have a functional digestive system… they literally don’t ever eat. Sustained only by the energy in his own tissues, the young male must find a female and mate before he starves to death. To aid in his quest, he has very well-developed eyes and huge nostrils, which allow him to follow the pheromone trail of a potential mate.

The somewhat less intimidating male anglerfish.
(Via: Anglerfish Info)

Now it gets weird. Upon locating a female, the male swims up and latches on to her with his teeth, usually on the lower side of her body. He then starts to release an enzyme which dissolves both his mouth and her skin, right down to their respective blood supplies. Soon, their bodies actually fuse together, and blood from the female begins to nourish the now-parasitic male. In some species, this fusion goes all the way to the base of the male’s skull, giving him the appearance of having his entire head absorbed into his mate’s body. Once fused, the male undergoes a growth spurt, thanks to his new food source, but his internal organs, as well as his eyes and nostrils, degenerate and atrophy. The exception, of course, being his testicles, which grow along with the rest of his outer body.

A female anglerfish and her clingy boyfriend.
(Via: Wikimedia Commons)

Her mate degenerated down to a mere sperm-producing external organ, the female anglerfish is now essentially a self-fertilizing hermaphrodite. With anywhere between one and eight males attached to her, she has an abundant supply of sperm available whenever she has ripe eggs to be fertilized. As for the males, they will “live” for as long as the female lives, and continue to reproduce indefinitely.

[Fun Fact: the species Ceratias holboelli has the most extreme size difference between the sexes. Females are more than 60 times the length and about half a million times heavier than the males.]

[And if you like your science lessons in cartoon form, be sure to check out this out.]

Says Who?

Come to Mama!
(Via: fugly.com)
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EVOLUTION TAG TEAM, Part 2: Sex & the Synconium

The second in an ongoing series of biology’s greatest duos. (Check out Parts One and Three)

(Via: Mastering Horticulture)

Common Name (Plants): Fig Trees

  • A.K.A.: Genus Ficus

Common Name (Wasps): Fig Wasps

  • A.K.A.: Family Agaonidae

Vital Stats:

  • Approximately 800 species of figs
  • Most are trees, but some are shrubs and vines
  • Approximately 640 species (20 genera) of fig wasps
  • All are obligate pollinators of figs

Found: Throughout the Tropics

It Does What?!

Snacked on any Fig Newtons lately? Tasty, right? Like the ad says, “A cookie is just a cookie, but a Newton is fruit and cake.”  …And wasps.

They must have run out of space on the package for that last part.

Before you toss out your favourite teatime treat, I should point out that without those wasps, the figs themselves wouldn’t exist. [Personally, I love Fig Newtons and will eat them regardless of any insects present.] This plant-insect pairing actually represents one of the most stable symbioses out there, with evidence suggesting it has existed for over 65 million years.

Now with 10% more Wings
(Via: Wikipedia)

While it’s not entirely clear how this arrangement evolved in the first place, fig trees produce a unique structure called a synconium, in which the flowers are actually inside the part we think of as the fruit. This synconium, which can contain up to 7000 flowers, depending on the fig species, has a tiny hole at the tip called an ostiole. In order for the flowers to be pollinated and the fruit to grow, a female wasp must squeeze through that hole, often losing her wings and antennae in the process, and distribute pollen that she carries in a sac on her abdomen. As she does so, she also uses her ovipositor to reach down into some of the female flowers and lay her eggs in their ovaries, where a gall is formed and the larvae can develop. Then she dies and ends up in a cookie. The End.

But hold on, let’s remove humans from the equation for a moment. She dies, but her eggs hatch into little moth larvae which use the growing fig for nutrition. Once they’re old enough, the young wasps mate with one another inside the fig (another nice mental image for snacktime), and the females gather pollen from the male flowers and store it inside their abdominal pollen baskets (yes, that’s actually what they’re called). The wingless male wasps have a simple, three step life: 1) mate with females, 2) chew a hole through the fig so they can leave, 3) die. That’s pretty much it for them. They may escape the nursery with the females, but they’ll die shortly thereafter, regardless. In fact, even the females have a pretty rough deal; from the time they’re old enough to mate, they have about forty-eight hours to get their eggs fertilized, gather pollen, find a new synconium, distribute the pollen, and lay their eggs. Two days, and their life is over. No pursuit of happiness for the fig wasp, I’m afraid.

“What does it all mean?”
(Via: BugGuide.net)

As with any long-standing mutualism, there are, of course, parasites ready and waiting to take advantage of it. These parasites are wasps which are able to enter the synconium and lay their eggs, but which do not pollinate the fig. Although their eggs will crowd out those of the fig wasps, decreasing the number of fig wasp larvae born, they are kept in check by the fact that any unpollinated synconium will be aborted by the tree and drop to the ground, taking the parasite eggs with it. The nonpollinating wasps are therefore kept from being a serious threat to the tree’s pollinators.

So there you have it, another of evolution’s great matches. The wasps get an edible nursery, the trees get pollinated, and we get tasty fruits with suspicious crunchy bits that probably aren’t dead wasp bodies, so just try not to think about it too much…

Seeds, or wasp eggs? You be the judge!
(Via: This Site)

[Fun Fact: The symbiosis between fig species and their corresponding wasp partners is so specific (often 1:1), that the shape of the ostiole actually matches the shape of the head of the wasp species which will pollinate it.]

[For those who would like to read about figs and fig wasps in much greater detail (such as how this works when the male and female flowers are in different figs), check out this excellent site for all you could ever want to know.]

Says Who?

  • Compton et al. (2010) Biology Letters 6: 838-842
  • Cook et al. (2004) Journal of Evolutionary Biology 17: 238-246
  • Kjellberg et al. (2001)Proceedings of the Royal Society of London, Biology 268: 1113-1121
  • Proffit et al. (2009) Entomologia Experimentalis et Applicata 131: 46-57
  • Zhang et al. (2009) Naturwissenschaften 96: 543-549
Posted on

How to Stay Cool the Lungfish Way

Via: Science News for Kids

Common Name: The Lungfish

A.K.A.: Subclass Dipnoi

Vital Stats:

  • 6 species; 4 in Africa, 1 in South America, 1 in Australia
  • Some species can reach up to 2m (6.6’) long and weigh 43kg (95lbs.)
  • Omnivorous, eating plants, insects, crustaceans, worms, fish, and frogs
  • Largest genome of all terrestrial vertebrates at ~133 billion base pairs

Found: Slow-moving freshwater bodies in South America, Africa, and Australia

It Does What?!

Well, they’re not much to look at, but in the “quietly carrying on while everything drops dead around you” department, the lungfishes are tops. These large, eel-looking creatures are what biologists refer to as “living fossils”, species which have existed in more or less their present form for a very, very long time. In the case of the lungfishes, around 400 million years. For the sake of comparison, this was around the same period that plants developed roots and leaves. That long ago. In fact, researchers believe that the lungfishes are the closest living relatives of the terrestrial vertebrates (that is, anything with a spinal column that lives on land).

These will probably outlast humanity.
Via: One More Generation

So what makes these things so interesting, besides being old? First off, they breathe air, as you might have guessed from their name. Australian lungfishes have a single lung, and, while they normally breathe through their gills, are able to supplement their oxygen intake with air during times of high exertion or when their water gets stale (Fun side note: During mating, Australian lungfishes make loud burping noises at the surface of the water which are thought to be part of the courtship ritual. I’ll refrain from making any Aussie jokes here… ). African and South American lungfishes, on the other hand, have two lungs and breathe nothing but air. Their gills are completely atrophied, such that they could actually drown if kept under for much longer than their usual 5-8 minutes between breaths.

“Hey! I’m trying to aestivate in here!”
Photo by: Tobias Musschoot

This ability to breathe without water results in the other fantastic ability of subclass Dipnoi. South American and African lungfish live in habitats which often dry up completely during the hottest part of the year. The fishes’ gross but brilliant answer to this is to burrow up to half a metre down into the soft mud and excrete a huge amount of mucous. As the surrounding mud dries up, the mucous forms a hard shell which keeps the curled up lungfish moist and cool. A small hole at the top of this snot-cocoon allows the fish to breathe. It’s metabolism slowed to only a small fraction of the normal rate, the creature will aestivate (like ‘hibernate’, but without the cold) like this for several months until the rains return. Laboratory experiments have shown that an African lungfish can remain alive under these conditions for as long as six years.

“Granddad”: probably older than your Granddad
Via: Shedd Aquarium

Aside from their amazing survival abilities, these fish have unusual lives, as fish go. They are extraordinarily long-lived. The Shedd Aquarium in Chicago holds an Australian lungfish known as “Granddad” which arrived there as an adult in 1933, making him at least 80 years old. Females of this species don’t even mate until they’re at least 22 years old (or so they tell their parents). What’s more, some species actually care for their young. The mother and father build an underwater nest for their offspring, which can only breathe via their semi-atrophied gills for the first seven weeks, and the father uses his body to release additional oxygen into the surrounding water, helping them to breathe. So, dual childcare: not such a new idea after all.

[Extra Credit –  Here’s a short video of a lungfish being stalked by a pelican. Spoiler: It ends badly for the lungfish.]

Says Who?

  • Brinkmann et al. (2004) Journal of Molecular Evolution 59: 834-848
  • Fishman et al. (1992) Proceedings of the American Philosophical Society 136(1): 61-72
  • Glass (2008) Respiratory Physiology & Neurobiology 160: 18-20
  • Joss (2006) General and Comparative Endocrinology 148: 285-289
  • Lee et al. (2006) General and Comparative Endocrinology 148: 306-314
  • www.fishbase.org
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What’s the matter, louse got your tongue? (Cymothoa exigua)

Via: Parasite of the Day

Common Name: The Tongue-Eating Louse

A.K.A.: Cymothoa exigua

Vital Stats:

  • Females are 8-29mm long by 4-14mm wide (0.3”-1.1” x 0.16”-0.55”)
  • Males are 7.5-15mm long by 3-7mm wide (0.3-0.6” x 0.12”-0.28”)
  • Preys on 8 species of fish from 4 different families

Found: In the Eastern Pacific, between the Southern U.S. and Ecuador

It Does What?!

With a name like “Tongue-Eating Louse”, you know this is going to be viscerally horrible, but bear with me… it’s also pretty neat. Despite the name, these aren’t actually lice, but parasitic crustaceans known as isopods. While there are dozens of species in the genus Cymothoa, most are parasites which live in the gills of fish and are, relatively speaking, unremarkable. But Cymothoa exigua is something special. While the male of the species (and this is a slippery term, as they can change sex when necessary) lives in fish gills, the female has developed an altogether original strategy.

Try to enjoy a tuna sandwich now.
Via: Smithsonian.com

Entering through the gills, the female takes up a position at the back of the fish’s mouth and attaches herself to the base of its tongue. She then pierces the tongue with her front appendages and begins to consume the blood inside it. Over time, the lack of bloodflow causes the tongue to slowly wither up and fall off. What’s left is a stump consisting of about 10% of the original tongue (yes, someone measured this). The parasite can now attach herself to the stump using her seven pairs of hook-like pereopods (read: ‘feet’) and actually begin to function as the fish’s tongue.

What’s really amazing is how well this seems to work. The parasite has evolved a body shape which closely matches the curves of the inside of the host’s mouth. Unlike our tongues, a fish tongue has no real musculature or flexibility; its only real function is to hold food against the fish’s teeth. With the parasite in place, the host is able to use its body to do exactly that. While the isopod is thought to feed on the fish’s blood, researchers have found that infected hosts have normal body weights and typical amounts of food in their digestive tract when caught. This is, to date, the only known case of a parasite functionally replacing an organ in its animal host.

Once it’s in there, this thing’s not coming out without a fight.
Via: This Site

Because edible snapper fish are amongst the host species of C. exigua, there have been cases of the parasite showing up in people’s supermarket purchases, including one person who thought they had been poisoned after eating one. So are they dangerous? Not to eat, no, but researchers tell us they can give a nasty little bite, given the opportunity. So the moral of this story is: if you bring home a fish for dinner and see an evil-looking parasite posing as its tongue… don’t stick your finger in its mouth.

.

Says Who?

  • Brusca & Gilligan (1983) Copeia 3: 813-816
  • Brusca (1981) Zoological Journal of the Linnean Society 73(2): 117-199
  • Williams & Bunkly-Williams (2003) Noticias de Galapagos 62: 21-23
See you in your nightmares.
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Advertising in the Wild… Not So Very Different (Ophrys sp.)

(Via: lastdragon.org)

Common Name: Bee Orchids

A.K.A.: Genus Ophrys

Vital Stats:

  • 30-40 recognised species in the genus
  • Grows to a height of 15-50 cm (6-20”)
  • The name Ophrys comes from a word meaning “eyebrow” in Greek, for the fuzzy edges of the petals
  • First mentioned in ancient Roman literature by Pliny the Elder (23-79 A.D.)

Found: Throughout most of Europe and the British Isles

It Does What?!

We tend to think of animals (including humans) as using plants to serve our ends exclusively- we eat them, clothe ourselves with them, build homes with them, and so on. But for all the obvious ways in which the animal kingdom takes advantage of the plants, there are numerous, more subtle, ways that they use us to do their bidding. One of those ways is as pollinators; plants enlist animals to help them reproduce. And while that enlistment often takes a rather mundane form – a bit of pollen brushed onto a bird’s head as it sips nectar, say – sometimes a group of plants will get a bit more creative about it. Such is the case with the bee orchids.

These highly specialised flowers depend on very specific relationships with their pollinators; often only a single species of bee (or wasp, in some cases) will pollinate a given species of orchid. Without those pollinators, the orchids can’t produce seed and would die out. So how do you control a free-roving creature that has other places to be? Why, sex, obviously. (Isn’t that the basis of most advertising?) The bee orchid has evolved a flower that not only looks, but smells like a virgin female of the bee species which pollinates it.

May not be appropriate for younger readers.
(Via: This Site)

At a distance, the bee detects the pheromones of a receptive female. Once he moves in closer, there she is, sitting on a flower, minding her own business. So he flies in and attempts to do his man-bee thing, only to find that he’s just tried to mate with a plant. Mortified (I imagine), he takes off, but with a small packet of pollen stuck to his head. He’s memorised the scent of this flower now and won’t return to it, but amazingly, the orchids vary their scent just slightly from one flower to the next, even on the same plant, so that the duped bee can never learn to distinguish an orchid from a female. What’s more, because the scent is more different between plants than between flowers on the same plant, he is more likely to proceed to a different plant, decreasing the chances that an orchid will self-fertilise.

Hilariously, researchers have shown that, due to their higher levels of scent variation compared to true female bees (variety being the spice of life, right guys?), male bees actually prefer the artificial pheromones of the orchids over real, live females. In experiments where males were given a choice between mating with an orchid and mating with a bee, they usually chose the flower, even if they had already experienced the real thing.

So there you have it. Plants: master manipulators of us poor, stupid animals.

Who could resist?
(Via: Wikia)

Says Who?

  • Ayasse et al. (2000) Evolution 54(6): 1995-2006
  • Ayasse et al. (2003) Proceedings of the Royal Society, London B. 270: 517-522
  • Streinzer et al. (2009) Journal of Experimental Biology 212: 1365-1370
  • Vereecken & Schiestl (2008) Proceedings of the National Academy of Science 105(21): 7484-7488
  • Vereecken et al. (2010) Botanical Review 76: 220-240