Back to the Deep, Part 2

(Via: Best-Diving.org)
(Via: Best-Diving.org)

Common Name: Whales, Dolphins, and Porpoises

A.K.A.:  Order Cetacea

Vital Stats:

  • While the lifespan of most whale species is unknown, evidence indicates bowhead whales can reach ages of around 200 years.
  • Sexual maturity in whales occurs at around 7-10 years of age.

Found: Throughout the world’s oceans, save the very northernmost regions

WhaleMap

It Does What?!

Last time, we looked at how whales evolved from a deer-like creature the size of a housecat into the aquatic behemoths they are today. This week, we’ll cover a couple of the odds and ends of whale weirdness.

One important thing to understand about evolution – particularly in cases of a major habitat shift, as we see in whales – is that it’s not an orderly or “well-thought out” process. A good analogy is to think of an old building that’s being renovated and rewired. New additions may be built onto old structures and new wiring overlaid on old plans, creating a product very different, and often much less efficient, from what would have been created were a new building made from scratch. Because you have to work with what’s already there.

Whale respiration is an excellent example of this point. When the ancestors of modern cetaceans took to the water, developing gills and breathing like fish wasn’t an option, because the machinery wasn’t intact… they were already much too far down the evolutionary path of a terrestrial mammal. What they could develop were more efficient lungs and greater control over how they used them. For humans, breathing is an unconscious and largely involuntary act – it just happens, whether we think about it or not, and we can’t choose to stop doing it for very long. Even if you were to hold your breath until you passed out, you’d just start breathing again the moment you lost control (take note, parents of tantrum-prone toddlers). For whales on the other hand, respiration has become voluntary; they breathe because they choose to do so. Life underwater and the need to hunt without distraction made this ability more valuable than the safety of an involuntary mechanism.

caption (Via:)
Whale-snoring.
(Via: The Telegraph)

There is, of course, a major drawback. For whales, control over respiration came at the price of ever being able to fully fall asleep. If a cetacean were to sleep as we do, it would stop breathing and drown. As a result, they’ve evolved the ability to sleep with one brain hemisphere at a time. So while one hemisphere rests, the other is awake, one eye is open, and the whale is in motion, surfacing periodically. In fact, they appear not to experience REM sleep at all, meaning that these creatures gained their mastery of the oceans, very literally, at the cost of their dreams.

Another interesting problem during whale evolution was that of temperature regulation. Anybody who’s been swimming knows that even relatively warm water can start to give you the chills after a while, especially if you’re not expending a lot of energy. This is because water is an excellent conductor of heat, and will constantly draw warmth away from the skin’s surface. Now once you get into the sunless depths of the ocean, to say nothing of the polar oceans that many whales live in, things get very chilly very fast. To counteract this, whales have developed a thick, insulating layer of fat that holds in the heat and keeps their core body temperature from plummeting. Easy peasy, right?

But what happens when the whale expends a lot of energy, say, on an intense feeding session, and builds up too much heat? Ever shovel snow in a heavy winter coat? After a few minutes, you’re ready to tear the coat off because you’re sweating so much. Not so easy when the coat’s under your skin. Well, researchers have recently discovered what they think may be the answer to this problem.

caption (Via: National Geographic)
That’s 144 inches, in case you were wondering.
(By: Craig George, Via: National Geographic)

In the bowhead whale, which lives exclusively in frigid arctic and sub-arctic waters (and therefore has a great deal of insulation), biologists found a mysterious, twelve foot long organ positioned along the roof of the mouth, made out of what is, essentially, the same tissue found inside penises. That is to say, spongy tissue filled with a lot of blood vessels which can expand as it fills with blood. So how does a giant mouth-penis help a whale cool off? It’s quite clever, really. The brain being the major point of concern for overheating, the organ, called the corpus cavernosum maxillaris, lies directly beneath it. Hot blood is pumped into the organ, filling the spongy tissue, as the whale opens its mouth, letting in a great volume of icy water which surrounds the engorged tissue, quickly drawing off much of the heat. The cetacean equivalent of a cold shower. This cooled blood then drains from the organ and lowers the temperature around the brain.

And if this extra-penis-as-thermoregulator wasn’t cool enough, it seems to have a secondary function as well. The organ is also packed with sensitive nerve endings (naturally…), which the researchers believe the whales may use to determine the prey density in a given area (bowheads are filter feeders), helping them to decide whether to remain in a location and feed, or move on in search of better pickings.

Fun Facts:

  • The ability to “sleep” with one eye open was likely also highly valuable to the much smaller ancestors of the cetaceans, for whom predation was a bigger problem.
  • Whales have fleshy nasal plugs with which they can plug their blowholes while diving.
  • Oceanic dolphins have the highest relative brain size among extant cetaceans.

Says Who?

  • Ford et al. (2013) The Anatomical Record 296: 701-708
  • Gatesy & O’Leary (2001) Trends in Ecology and Evolution 16(10): 562-570
  • Gatesy et al. (2013) Molecular Phylogenetics and Evolution 66: 479-506
  • Lyamin et al. (2008) Neuroscience and Behavioral Reviews 32: 1451-1484
  • Uhen (2010) Annual Review of Earth and Planetary Sciences 38: 189-219
  • Zimmer (2013) The Loom, March 4th.

Back to the Deep, Part 1

(Via: Wikimedia Commons)
(Via: Wikimedia Commons)

Common Name: Whales, Dolphins, and Porpoises

A.K.A.:  Order Cetacea of Class Mammalia

Vital Stats:

  • Consists of 88 living species
  • Order is divided into Odontoceti, the toothed whales (73 sp.), and Mysticeti, the baleen whales (15 sp.)
  • Odontoceti includes both dolphins and porpoises
  • The largest whale, a blue whale, can grow up to 30m (98’) in length and weigh as much as 20 elephants

Found: Throughout the world’s oceans, save the very northernmost regions

WhaleMap

It Does What?!

caption (By: Nobu Tamura, via: Wikimedia Commons)
The twenty pound vermin that went on to rule the oceans.
(By: Nobu Tamura, via: Wikimedia Commons)

Picture it: the time is just over 50 million years before the present – the early Eocene – the climate is much warmer than today, undergoing a period of rapid global warming… it is the Age of Mammals. On the shores of the tropical Tethys Sea, in what would eventually become India, a small, deer-like animal, not much larger than a housecat, wades into the water and dives briefly to retrieve a fish before returning to dry land. This has become a successful strategy for its species, avoiding competition from other mammals by eating marine life. Well-fed, the creatures reproduce rapidly, creating competition amongst themselves. Those individuals with greater lung capacity and better swimming ability catch more food, outcompeting those who don’t. Over great stretches of time, characteristics enabling speed and skill under water become more important than those enabling life on land, and selection tilts in favour of a longer, more lithe body, smaller hindlimbs, stronger forelimbs for paddling, and less fur.

caption (Via: AccessScience)
Swimming: great for a slim figure.
(Via: AccessScience)

Millions of years pass as our small hunter’s descendants eventually lose the ability to ever return to land. They have no fur now… it isn’t useful for retaining heat beneath the waves. Fat is, though, and this begins to accumulate in thicker layers under their bare skin. Their front legs are nearly inflexible at the joints, trading range of movement for strength and widening into precision rudders to control direction as they swim. In concert, the tail becomes more muscular and widens into flukes at the tip, propelling them forward powerfully with each stroke. Their back legs – unneeded – atrophy, gradually losing both size and bone structure, until the foot is completely gone. A small stub lingers for a time before the last vestigial bones simply remain inside the smooth body wall, evidence of a distant terrestrial past. The nasal opening has migrated to the top of the head for ease in surface breathing. Ten million years have passed since the scene on the shore, and we now have our first fully aquatic whale.

Of course, much still had to happen before we arrived at the whales of today. In the time since aquatic mammals first arose, a major division took place within the Cetacea. One group, the toothed whales, or Odontoceti, continued to hunt and eat fish and large marine fauna, including squid and even other whales. To aid in finding their prey, these whales developed echolocation, the use of projected sound to create an image of the surrounding area, thereby becoming the loudest mammal, with vocalisations of more than 180 decibels (a jackhammer tops out at about 120dB). The large bulge we see on the forehead of dolphins and other toothed cetaceans is an organ called a ‘melon’ (because they couldn’t think of anything more science-y sounding just then), which is thought to help direct and focus these sounds.

caption (Via: Wikimedia Commons)
Who needs teeth when you can have a broom in your mouth?
(Via: Wikimedia Commons)

Being a top-level predator isn’t very energetically efficient, though, and there isn’t always enough prey to go around. So at some point, one group of whales began to move toward a different strategy. The origins of the Mysticeti, the baleen whales, are still a bit unclear, but these animals switched from hunting large fauna to eating colossal numbers of tiny sea creatures such as krill. In order to do this, the whales lost their teeth and developed baleen in their place. Baleen is essentially a fine-toothed comb that filters small animals from the water as it passes. The whale takes a giant mouthful of water and pushes it out against the combs until only food remains. While this may seem less efficient than just grabbing a big fish and eating it, filter feeding is what allowed the largest whales to evolve to their present size. The blue whale, Balaenoptera musculus, is believed to be the largest animal which has ever existed on Earth, and it got that way eating mostly shrimp the size of your thumbnail. Amazing, isn’t it?

Now that we’ve covered how they got that way, tune in next time for part two, where we’ll explore the many weird and wonderful aspects of life as a modern whale.

Fun Facts:

  • Baleen whales still have teeth during the embryonic stage of their development, much as human fetuses briefly develop tails.
  • Toothed whales do not chew their food; it is eaten whole or torn into large pieces and swallowed. This may be related to the fact that, unlike most mammals, they have only one set of teeth.

Says Who?

  • Gatesy & O’Leary (2001) Trends in Ecology and Evolution 16(10): 562-570
  • Gatesy et al. (2013) Molecular Phylogenetics and Evolution 66: 479-506
  • Lyamin et al. (2008) Neuroscience and Behavioral Reviews 32: 1451-1484
  • Uhen (2010) Annual Review of Earth and Planetary Sciences 38: 189-219

The Devil You Know, the Devil You Don’t

(Via: Wikimedia Commons)
(Via: Wikimedia Commons)

Common Name: The Tasmanian Devil

A.K.A.Sarcophilus harrisii (Family Dasyuridae)

Vital Stats:

  • Latin name translates to “Harris’s Meat Lover” after naturalist George Harris
  • Weigh 6-13kg (13-29lbs.), around the size of a small dog
  • Largest carnivorous marsupials in the world after the extinction of the thylacine in 1936
  • Live up to five years in the wild; fully grown at two years of age

Found: On the Australian island-state of Tasmania

Devil Map

It Does What?!

Spins around in circles and chases talking rabbits, if the cartoons are to be believed. But Tasmanian devils have suffered from some bad press over the years. While they’re often portrayed as incurably vicious, dangerous creatures, this isn’t really the whole truth. Yes, they can scream like a person getting dismembered. And yes, they’re good little hunters that can take down prey larger than themselves, partly thanks to having the strongest bite per unit body mass of any living mammal. (Crunching through large bones is not a tall order for a Tasmanian devil.) But they just as often scavenge carrion killed by other causes, frequently in the form of roadkill. They don’t tend to attack humans, either (unless that human happens to be dead already). Faced with live humans, devils will usually just hold still and hope you don’t see them, sometimes trembling nervously as they do so. Doesn’t exactly strike fear into your heart, does it?

caption(Via:)
How many newborn devils CAN you fit on a 20 cent piece?
(Via: 500 Questions)

In fact, more than anything, devils deserve a bit of sympathy (just ask the ‘Stones)… life is tough for them right from the word ‘go.’ You see, Tasmanian devils are marsupial, meaning the young are born very under-developed and must crawl from the birth canal into their mother’s pouch to find a nipple to latch onto while they finish baking. The problem here is, devils give birth to between twenty and thirty babies, but possess only four nipples, which aren’t shared. In fact, they’re effectively stuck in the infant’s mouth from the time they latch on, preventing them from falling out of the mother’s pouch. So as newborn babies, fresh from the womb, they already have as much as an 87% chance of immediate death. That is some harsh selection right there. Somewhat tellingly, the babies can’t open their eyes until three months after their birth, yet come out of the womb with a full (if small) set of claws. You can see where evolution’s priorities were here.

But it doesn’t get much easier for the four that win the nipple race. Tasmanian devils are already working with a rather restricted range, having been hunted to local extinction on mainland Australia around 3000 years ago (probably by dingoes, which aren’t found in Tasmania). Nevertheless, they were doing pretty well in keeping their numbers up and had a healthy population until the mid-90s, when disaster struck.

caption(Via: Wikimedia Commons)
Don’t image-search this disease… it gets so much worse.
(Via: Wikimedia Commons)

Because the entire Tasmanian population of devils was originally based on only a few individuals, they’ve experienced a ‘Founder Effect,’ which basically means that the genetic diversity from one animal to the next is quite low. In terms of disease, they’re all susceptible to the same things. So when a form of transmissible cancer known as Devil Facial Tumour Disease (DFTD) suddenly popped up in 1996, it spread like wildfire from one devil to the next, mostly via their tendency to bite one another during sex and mealtimes.

An infected devil quickly develops tumours on its face and inside its mouth. This eventually makes it difficult to eat, leading to starvation within a year of contracting the disease. DFTD is estimated to have already killed up to 50% of all devils, rushing them from a healthy population to an endangered species in record time. While the government has taken the step of building up a healthy, captive population which will be isolated from the disease, in the long term, this will have the effect of reducing the species genetic diversity even further. As a small glimmer of hope, researchers are now reported to have found a few individuals with at least partial immunity to the disease, and hope to try to build a cure based on their physiology.

caption(Via:)
Bitey the Devil picks a fight.
(Via: TravelerFolio)

Fun Facts:

  • Tasmanian devils store fat reserves in their tails… a fat-tailed devil is a healthy devil.
  • See the white spots on the devil pictured above? All bite marks. Each scar leaves a patch of white fur. The natural white streak on the devil’s thick-skinned chest is thought to draw attacks away from more sensitive areas.
  • Unlike most other marsupials, the devil’s pouch opens to the rear of her body rather than the front (like a kangaroo), making it impossible for her to interact with her babies while they’re nursing there.
  • Devils tend to try to eat whatever’s available when they’re hungry. The following have been found in their droppings: steel wool pot scrapers, tea towels, parts of leather shoes, blue jeans, plastic fragments, dog collars (minus the unfortunate dog that had been in it), and echidna spines.
  • The only other known form of non-viral, transmissible cancer is a type of venereal disease that occurs in dogs.

Says Who?

  • Attard et al. (2011) Journal of Zoology 285: 292-300
  • Coghlan (2012) “’Immortal’ Tasmanian devil brings vaccine hope” New Scientist, 17 February
  • Grzelewski (2002) Smithsonian 68: February
  • Hamede et al. (2013) Journal of Animal Ecology 82: 182-190
  • Hesterman et al. (2008) Journal of Zoology 275: 130-138
  • Marshall (2011) “Tasmanian devils were sitting ducks for deadly cancer” New Scientist, 27 June

Axolotls in Never Never Land

(Via: National Geographic)
(Via: National Geographic)

Common Name: Axolotls

A.K.A.: Ambystoma mexicanum

Vital Stats:

  • Grow to a length of 15-45cm (6-18”)
  • Can live up to 15 years
  • Have no eyelids
  • Usually black or brown in colour, but mutation occasionally produces pink skin
  • Eat insects, worms, and small aquatic animals
  • Commonly kept as pets and, in parts of Mexico, food

Found: In the Xochimilco lake system, near Mexico City

Axolotl Map

It Does What?!

Axolotls are the Lost Boys of the amphibian world… they never grow up. These bizarre little salamanders are found only in a single lake system near Mexico City and, if the city’s pollution gets much worse, may soon not be found there, either.

First, a little background on salamanders in general. These amphibious, lizard-like creatures begin life in a larval stage. While adult salamanders have lungs and spend much of their time out of the water, larvae have only gills and are completely aquatic. They commonly undergo a metamorphosis in which the gills are lost and the body changes shape, thinning out and losing its ‘tadpole with legs’ appearance. Many salamanders have displayed the ability to occasionally forego metamorphosis, remaining in their larval stage for life. This phenomenon of looking like a juvenile even during adulthood is called “neoteny.”

caption(via:)
The “fully cooked” version.
(Via: Wikimedia Commons)

What makes axolotls special is that they’re what’s called “obligate neotenes,” meaning they simply never go through metamorphosis… every adult axolotl looks like the larval stage of other salamander species. At some point in their evolution, it became either more beneficial or downright necessary for them to remain aquatic. Biologists have speculated that this is because their smaller larval form requires less food, and because the lakes where they live are low in iodine, an element required for their transformation.

Interestingly, while axolotls almost never go through metamorphosis in the wild, in a certain percentage of them, the genetic instructions for doing so seem to still be intact. If you have a larval axolotl and you want an adult form, you can either give it an injection of iodine, or, for the more deranged among you, gradually deprive it of its pool of water. Either method of forced metamorphosis has a high mortality rate and, at best, causes a hugely decreased lifespan, but it does show they haven’t entirely lost that capacity.

caption(From:)
The future of multi-tasking.
(From: McCusker & Gardiner (2011) Gerontology 57: 565)

An eternally youthful appearance isn’t even the axolotls’ only superpower. The creatures also possess a Wolverine-like ability to heal themselves. Not only can they – and other salamanders – regrow lost limbs, they can actually regenerate parts of vital organs, including sections of the brain, spinal cord, and, in one study, up to 50% of the heart ventricle. Axolotls can also receive organ transplants from other individuals without rejection or problems with lack of function in the new tissue. Obviously, these traits have made them of intense interest to a certain species which doesn’t regrow limbs, hearts, or spinal cords. Researchers hope that by studying the genetic and biochemical basis of these heightened healing abilities, they can create their own army of X-Men help amputees and victims of spinal cord injuries. But this research is still in its early stages. In the meantime, it would probably be in our best interests not to drive them to extinction.

Fun Facts:

  • Axolotls have tiny vestigial teeth, which in other salamanders only grow during metamorphosis.
  • Sometimes, an axolotl with a heavily damaged limb will both repair the old limb and regrow a new one, ending up with an extra leg (see above).
  • Forced metamorphosis can be only half-successful, producing adult forms with juvenile characteristics, such as a thickened neck.
  • Obligate neotenes like axolotls end up with a lot of extra “junk” DNA [biologists: via duplications of the pseudogenes created when their life history changed], which has actually resulted in their having larger cells than other salamanders.

    caption(Via:)
    It’s hard not to look crazy when you have no eyelids.
    (Via: Aquadisiac News)

Says Who?

  • Chernoff (1996) International Journal of Developmental Biology 40: 823-831
  • Martin & Gordon (1995) Journal of Evolutionary Biology 8: 339-354
  • Neff et al. (1996) International Journal of Developmental Biology 40: 719-725
  • Rosenkilde & Ussing (1996) International Journal of Developmental Biology 40: 665-673

The Old Girls’ Club

(Photo by the Author)
(Photo by the Author)

Common Name: African Elephants, Asian Elephants

A.K.A.: Loxodonta africana, Elephas maximus

Vital Stats:

  • Comprise the entirety of Family Elephantidae and Order Proboscidea
  • African elephants are thought by some to be two species; the African Forest Elephant, and the African Bush Elephant
  • Can live for up to 70 years in the wild
  • The largest living terrestrial animals, reaching heights of up to 4m (13’) and weights of up to 7000kg (15,000lbs.)
  • Consume up to 150kg (330lbs.) of food daily

Found: Savannahs, bushlands, and forests in sub-Saharan Africa and Southeast Asia (but sparsely across these regions)

Elephant Map

It Does What?!

Everyone knows elephants are cool. And weird looking. What they don’t tend to get a lot of credit for is just what complex lives they live, and how well-adapted they are to their surroundings. Far from being the dim, bovine, eating machines they’re often depicted as, elephants have been found to have an intelligence and self-awareness ranking up around that of primates and cetaceans, with comparably nuanced societies.

caption(Via:)
Jumbo renounces vegetarianism.
(Via: One Big Photo)

Elephant herds are matriarchal, being led by the oldest female and consisting of her close female relatives and their young offspring. Males are given the boot around the time they reach sexual maturity during their teens (because even the most intelligent animals find teenage boys a trial) and live the rest of their lives either alone or with a small pack of other exiled males.

Good parenting and discipline (delivered by mom with a swat of the trunk) seem to be extremely important for young male elephants; when orphaned males were introduced to a game reserve in South Africa in the late ‘90s, they immediately began going on killing sprees, hunting down and violently killing over 30 (endangered) rhinos, a completely abnormal behaviour for an elephant. As soon as well-adjusted adult males were introduced, the aggression stopped. Everybody needs a good role-model, I guess.

You may have heard stories about so-called “elephant graveyards,” where elephants go to die and leave remains near those of their relatives. While these have now been found to be a myth, appearing due to large die-offs happening suddenly in times of drought, it’s true that elephants show an inordinate amount of interest in the carcasses and bones of other elephants. Presented with a set of bones, elephants will become highly agitated and touch the bones repeatedly with their trunks, especially the dead animal’s tusks. Researchers speculate that this is because the tusks feel the same as they did in life, and touching is such an important aspect of elephant society. They are the only known animal outside of humans to take a particular interest in the bones of their species.

caption(Via:)
Probably not what evolution intended.
(Via: The Road to Anywhere)

And what about their most obviously bizarre feature? How did a prehensile nose develop?! It’s hard to say for sure, but one interesting theory comes from the fact that elephants use their trunks as snorkels while swimming, sometimes crossing shallow lakes by simply walking across the bottom with only their noses above water. Given that manatees are one of elephants’ closest relatives, some scientists have speculated that elephants evolved from aquatic mammals, slowly becoming terrestrial, but never losing their once-important snorkel. (Or their internal testicles, another trait associated with an aquatic lifestyle.) Other scientists think those guys don’t know what they’re talking about and lack evidence to support this theory. So it goes in science.

Whatever their origin, elephants’ trunks have become enormously important in their lives, and are used in everything from eating to fighting to bonding with family members. Actually a fusion of the nose and upper lip, trunks have over 100,000 muscles and are sensitive enough to crack open a peanut shell and retrieve the seed from it. The ability to grasp comes from one or two (in Asian and African elephants, respectively) finger-like extensions at the trunk’s tip. These “fingers,” combined with the elephants’ high degree of intelligence, have allowed them to learn the use of several tools, including tree-branch fly-swatters, which they probably invented millions of years before we came up with the idea. Different priorities…

caption(Via: Wikimedia Commons)
Yeah, we definitely need a few more of these.
(Via: Wikimedia Commons)

And finally, let’s not forget the dearly departed cousins. While African and Asian elephants are the only remaining species of Proboscidea, the order containing both mammoths and mastodons, there were once over 160 of them, inhabiting every continent except Australia and Antarctica. Most of these persisted until the most recent ice age killed off nearly all of the largest mammals. Some systematists believe that Asian elephants are in fact more closely related to woolly mammoths than they are to African elephants, and it’s even been speculated that a cloned mammoth could some day be gestated in the womb of an Asian elephant. ‘Cause if we learned anything from Jurassic Park, it’s that reanimating extinct megafauna is a great idea.

Fun Facts:

  • Elephants use ‘seismic communication,’ transmitting messages via a low-pitched rumble, which is detected by distant elephants using the pads of their feet.
  • While they can move surprisingly quickly, elephants don’t technically “run,” due to the fact that their legs never all leave the ground simultaneously.
  • It’s a common myth that elephants get drunk eating fermented marula fruits which have fallen to the ground. Given the low level of alcohol which accumulates in rotting fruit, an animal the size of an elephant would have to eat an unrealistically huge amount in a short time to reach a high enough blood alcohol level. But they do seem to enjoy them as a snack.

Says Who?

  • Choi (2011) “Woolly Mammoths Could Be Cloned Someday, Scientist Says”. Live Science.
  • McComb et al. (2006) Biology Letters 2: 26-28
  • Morris et al. (2006) Physiological and Biochemical Zoology 79(2): 363-369
  • Shoshani (1998) TREE 13(12): 480-487
  • Shoshani & Tassy (2005) Quaternary International 126-128: 5-20
  • Shoshani et al. (2006) Brain Research Bulletin 70: 124-157
  • West (2002) Physiology 17: 47-50

The Cost of Eighty Million Years in Paradise

(Via: The Life of Animals)

Common Name: The Kakapo, The Owl Parrot

A.K.A.: Strigops habroptila

Vital Stats:

  • Males can grow up to 60cm (24”) long and weigh up to 4kg (8.8lbs.)
  • Average life expectancy of a healthy kakapo is 95 years
  • Breeding begins around age 9; females lay 1-3 eggs per clutch
  • Main mammalian predators are rats, cats, ferrets, and weasels

Found: Traditionally, across large areas of both major islands of New Zealand; today, mostly on small, protected island reserves nearby

It Does What?!

Strange things happen when you leave a few species alone on a distant island for a few million years. Places like New Zealand, Australia, Madagascar, and Hawaii are (or were) full of plants and animals that seem alien compared to rest-of-the-world standards. This is often due to a set of conditions and evolutionary challenges unlike those seen on the continent. Life on New Zealand is particularly interesting, having been heavily shaped by the fact that the only terrestrial mammals there are bats. Every animal that evolved there did so without the pressure of having to avoid toothy predators stalking them through the forest. Ever wonder what birds would be like without anything on the ground trying to kill them?

“I’m just big boned, okay?”
(Via: Gothic Atheist)

If so, meet the kakapo, the world’s largest, fattest parrot. And the only one that can’t fly. Isolated in New Zealand when the islands separated from the continent over eighty million years ago, the native parrots eventually lost their strong flight muscles and stiff, rigid wing feathers, trading them for greater size and the ability to store a half inch thick layer of fat under their skin to sustain them in lean times. This change also slowed their metabolism, resulting in their being one of the longest-lived birds out there, with a maximum recorded age of 120 years. Slothlike, these peaceful, nocturnal creatures spend most of their waking hours climbing (yes, climbing) from tree to tree, eating fruit and foliage. Unlike sloths, however, they can take a quicker route down, simply leaping from the tree and spreading their stumpy wings in what’s probably a very amusing imitation of a parachute. Unsurprisingly, they’ve developed quite strong legs, and can cover distances of several kilometres at a jog.

The most fascinating aspect of the kakapo lifestyle, though, has to be its mating routine. Unlike most parrots, kakapos aren’t monogamous and don’t share parenting duties. Every three to six years, when fruit crops are particularly good, male kakapos will stake out a small territory on high ground, fighting with other males for the best spots. The “best spots” in this case being those with the best acoustic qualities, such as those backed by a rock wall which can reflect sound outward over the land. Having obtained his mating area, he will construct a series of pristine paths leading up to it (for the ladies), as well as a large bowl-shaped depression in the earth, which acts as an amplifier. Kakapo-sound-system completed, he’s ready to get down to business. The male stands in his bowl, inflates a sac in his chest, and emits a series of eerie, low frequency booms, like distant cannons, loud enough to be heard several kilometres away. He continues to do this, all night, every night, for up to four months, losing up to half his body weight in the process. The female kakapo has it somewhat easier. She simply approaches the emitter of her favourite booms, he performs a short dance routine for her, she gets what she came for, then walks on home to lay her eggs.

“I could hide better if you two would quit staring.”
(Via: Pour L’animal)

Before the colonisation of New Zealand, the islands were reportedly teeming with these birds, so successfully specialised were they for their unusual environment. Their only natural predators were birds of prey, from which they hid by freezing and blending into the surrounding greenery. Sadly, specialisation is often a one-way street that you can’t back out of if your environment suddenly changes. The features that made the defenseless kakapos good at avoiding avian predators (like their tendency to freeze), made them terrible at avoiding the carnivorous mammals, such as cats, that came with colonisation. Despite having powerful legs with large claws, the birds seem unaware that they can be used as weapons. Worse, their natural curiosity and lack of fear in approaching humans often landed them on both Maori and European dinner tables.

Enormous efforts have been made over the last century to prevent these big, gentle birds from going extinct. As of this year, there are still only 126 known to exist (each with its own name and radio transmitter), but they are a slowly expanding population, thanks to their relocation to three protected, largely predator-free islands. Expectant mothers even have their own nest watchers, who sneak in to cover the nests with electric blankets while mom pops out for a bite. Free babysitting- seems like the least we can do.

“How do YOU like it?!”
(Via: BBC’s Last Chance to See)

[Fun Fact: Conservationists have had to scale back on the supplemental food they had been giving the kakapos during mating season. It turns out a well-fed kakapo will produce mostly male chicks. Not what you need when you’re trying to rebuild a population.]

[Also: Kakapos use their fine facial feathers like whiskers, walking with their faces near the ground to sense the terrain.]

Says Who?

  • Douglas Adams & Mark Carwardine (1990) Last Chance to See. Pan Books, London [This is a fantastic book. Highly recommended.]
  • Grzelewski (2002) Smithsonian Magazine, October Issue
  • Sutherland (2002) Nature 419: 265-266

The Stench of Death, brought to you by the Forests of Sumatra

(Via: The Parasitic Plant Connection)

Common Name: Giant Rafflesia

A.K.A.: Rafflesia arnoldii

Vital Stats:

  • One of about 28 species of Rafflesia, all parasites native to southeast Asia
  • Dioecious: produces male and female flowers on separate plants
  • Flowers last only a few days

Found: In the rainforests of Sumatra, Western Indonesia

It Does What?!

In my very first post here on Questionable Evolution, I discussed the Titan Arum, a.k.a. Corpse Plant, known for its pungent aroma and generally phallic appearance. This rare oddity is confined to the ever-shrinking rainforests of the western Indonesian island of Sumatra. Now meet its neighbour and fellow rotting flesh imitator, the Giant Rafflesia. Like the Titan Arum, this species is found only in the Sumatran rainforest and uses its odour to attract carrion flies for pollination. (With all the plants pretending to be dead animals on this island, it’s a wonder the flies ever actually find themselves any real carcasses.)

How big?  THAT big.
(With Mr. Troy Davis, Via: The Parasitic Plant Connection)

Rafflesia’s claim to fame in the plant world is that it produces the largest flower on Earth. A single bloom from Rafflesia arnoldii can reach a diameter of 1m (3.3’) and a mass of up to 7kg (15lbs.). In other words, one flower weighs about as much as your overweight cat. Impressive, sure, but what’s more interesting about this plant is that the flower’s the only part of it you’re ever likely to see.

Much like dodder, rafflesia is a holoparasite, depending entirely on a host plant (in this case, a vine of genus Tetrastigma, part of the grape family) for its water and nutrients. Unlike dodder, however, rafflesia doesn’t grow up and over its victim, eventually smothering it- no, this plant grows inside its host. Over the course of its evolution, the leaves, roots, and stems of rafflesia have been reduced to nothing but miniscule threads that grow, fungus-like, through the intercellular spaces of another plant, absorbing whatever they require. The giant flower arises directly from the roots or stem of the host vine, pushed out through the host’s tissues. Think chestbursters from Alien. Beyond the juvenile phase when a new seedling searches for its host, this is the only part of rafflesia that will ever see the light of day.

Flowering Time!!

Interestingly, botanists have found that rafflesia’s giant flowers evolved over a very short period of time (relatively speaking), with flower diameter increases of, on average, 20cm per million years. Blindingly fast, as plant evolution goes. The reason for this, they speculate, may have been a preference on the part of certain carrion flies to feed on larger animal carcasses. The range of flower sizes seen in different species of genus Rafflesia probably functions to attract different sets of fly species with varying tastes – some want wee little dead mice, some want dead rhinoceros, judging from the size of these things.

Plants: give ‘em a few million years, and they can mimic almost anything.

Says Who?

  • Barkman et al. (2008) Current Biology 18: 1508-1513
  • Beaman et al. (1988) American Journal of Botany 75(8): 1148-1162
  • Patifino et al. (2002) New Phytologist 154: 429-437

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)

The Plant That Time Forgot (Welwitschia mirabilis)

(Via: Wikimedia Commons)

Common Name: Welwitschia mirabilis

A.K.A.: Welwitschia

Vital Stats:

  • Welwitschia is a gymnosperm, like pines or firs, and thus reproduces via male and female cones
  • Considered a “living fossil”
  • Named after one of its discoverers, Austrian botanist Friedrich Welwitsch
  • In mature specimens, the woody stem can grow up to one metre (3.3’) across

Found: In the Namib desert, along the west coast of Namibia and Angola

It Does What?!

Restricted to a tiny, arid swath of African desert, Welwitschia mirabilis represents the last remaining species of a very unusual lineage of plants. Close relatives met with extinction over the aeons, while welwitschia, tucked away in its remote and harsh desert range with little competition, just kept going. The fact that the species is alone, not just in its genus, but also in its family and order (the two ranks above genus in plant systematics), speaks to just how distantly related to any other living plant it is. For the sake of comparison, the Rosales, the order to which roses, apples, and pears belong, contains around 7700 species in 9 families and 260 genera. So original and captivating is welwitschia among plants that it has been the subject of more than 250 scientific articles since it was first described in 1863.

A mere infant. But probably still older than you are.
(Via: Lizworld.com)

So what makes this thing so weird? Well, plants typically have what’s called an apical meristem at the tips of their stems and/or branches. You can think of this as a clump of stem cells that keeps dividing, throwing off new leaves and buds in its wake. If you cut off the apical meristem, the plant must either develop a new one elsewhere, or stop producing new tissue.

In welwitschia, this isn’t the case. At the beginning of the plant’s life, the apical meristem produces just two leaves, and then dies. The plant will never grow another leaf, which is much more surprising when you consider that it may well live for more than a thousand years. How do you get through a millennium with only two leaves?! The answer is, these aren’t ordinary leaves. Uniquely, welwitschia’s two strap-like leaves have a band of meristematic tissue built into their base, which means they can continue to elongate outward indefinitely. The leaves will continue to grow at a rate of around half a millimetre (0.02”) per day for as long as the plant lives. If you’re thinking that this must mean leaves that are several hundred metres long, unfortunately, no, they aren’t. The leaves are abraded away by sand storms and eaten by passing animals. Even in the best case scenario, the cells at the leaf tips have a maximum lifetime of about ten years (still pretty good for a leaf…). What’s more, the leaves tend to get frayed and split over time, and end up looking like a lot more than just two leaves. Despite all the punishment, though, each leaf can reach a length of up to four metres (13’), giving a mature welwitschia a width of up to eight metres (26’) across.

Welwitschia’s answer to the pinecone.
(Image by Friedrich A. Lohmuller)

As you might expect from a long-lived relic of the past, there aren’t a lot of these plants around. For once, this has less to do with human disturbance than natural circumstances. Over millions of years, the range where welwitschia grows has dried out considerably, and in fact continues to get drier even now. Today, the plant relies largely on fog to meet its water needs, restricting its range to a thin strip of desert coastline where fogs occur regularly. Unlike cactuses or succulents, welwitschia has never evolved the ability to store water. Also problematic is a fungus, Aspergillus niger, which frequently infects and destroys germinating seeds. These factors together can mean that a welwitschia colony can sometimes go many years without successfully reproducing.

And of course, no threatened species would be complete without some human interference. In recent decades, unscrupulous collectors have removed plants from already small breeding populations, making it even more difficult to sustain their numbers. Interestingly, it’s noted in Wikipedia that plants in Angola are actually better protected from collecting than those in Namibia due to the higher concentration of landmines there.

So… landmines: bad for humans, good for endangered plants.

You think you have problems with split ends?
(Via: Natural History Museum)

Says Who?

  • The Gymnosperm Database
  • Dilcher et al. (2005) American Journal of Botany 92(8):1294-1310
  • Henschel & Seely (2000) Plant Ecology 150:7-26
  • Jacobson & Lester (2003) Journal of Heredity 94(3):212-217
  • Rodin (1958) American Journal of Botany 45(2):96-103

The Plight of the Spheroid Seaweed (Aegagropila linnaei)

Everyone’s Favourite Freshwater Pet
(via: http://commons.wikimedia.org/wiki)

Common Name: Lake Balls, Marimo

A.K.A.: Aegagropila linnaei

Found: Japan, Iceland, Scotland, Estonia, Germany

It Does What?!

Sure, you’ve had dogs and cats as pets, maybe even fish or lizards… but what about a big ball of algae? Probably not, but if you live in Japan, this idea won’t seem so odd.

Lake balls, or marimo, as the Japanese refer to them, are a rare and unique growth form of the filamentous green algae species Aegagropila linnaei. They occur in only a few isolated habitats worldwide because, unlike most algae, the species lacks a desiccation (dryness) resistant life stage which would allow it to be carried to distant bodies of water. The balls are formed from a densely-packed clump of algal strands which grow outward in all directions, and can reach up to 25cm (10 inches) in diameter. New balls can form from the free-floating form of the same species, or from the breakup and re-growth of an old ball. Found in shallow lakes with sandy bottoms, gentle wave action rolls the clump around, forming a near-perfect sphere and allowing all sides of the ball to receive light for photosynthesis. Seen rolling lazily around the lake bottom, and even rising and falling on columns of warm water, the marimo can almost seem sentient.

It is this bizarre movement and their strangely beautiful appearance which have made marimo so popular in Japan, where they are protected as a “natural monument” and even appear on postage stamps. Unfortunately, it has also been their downfall. Because the algae reside in fresh water and are adapted to low light conditions, they are easily cared for, leading many people to collect them and keep them in their homes. The Japanese believed that a healthy, well looked-after marimo would make the owner’s wishes come true. Lake balls eventually became so rare, due to both human collecting and pollution, that in the early 1950s, a campaign was launched asking Japanese citizens to return their beloved marimo to the lakes from which they had been taken. Impressively, people did so, and in large numbers. In honour of their selflessness, the first annual marimo festival was held, and has continued ever since. Today, the lake ball has become an important environmental symbol in Japan, and children even have their own stuffed marimo toy character, Marimokkori, to play with.

Japanese kids have the best toys, no?

Says Who?

  • Boedeker et al. (2010) BioScience 60(3): 187-198
  • Soejima et al. (2009) Aquatic Ecology 43: 359-370
  • www.marimoballs.com