Patterns in Nature

This month's "theme" is Patterns in Nature: interesting shapes or colours found in nature. I have chosen an extraordinary eucalyptus tree, zebras, a puzzling butterfly, and some neat-looking microorganisms. Although there are many more examples, - especially in the case of flowers - the four seen in the photo are my favourite. :)

The bark of the rainbow eucalyptus tree is one of the most extraordinary patterns in nature. It looks as though someone took a brush and painted the tree; however, this is not the cause of this spectacular coloration.


The bark consists of a variety of colourful hues, and if you look closely at it, it is peeling. It is this peeling, that is responsible for the multicoloured bark.


Fine layers of bark peel in strips of varying shape and size, revealing a smooth, white to pale green surface, which with age turns to vibrant green, grey, pink, red, orange, blue, and purple. The colour change is induced by the sun, which influences the bark's pigment centres. (The process is analogous to leaves changing colour in Fall, or tanning hides).

This is the only species of eucalyptus to be found in the Northern Hemisphere, and the more tropical the habitat, the more pronounced the "rainbow effect" becomes! (more sun yields more pigment alteration).

There are three species of Zebras, and all of them are bizarrely striped. Like the fingerprints of humans, the striping pattern of any individual zebra is unique from any other. The stripes of zebras have always been an interesting puzzle to scientists - but what purpose do they serve?

If you've ever rode a horse, or even near one, you probably noticed flies swarming all over it. Flies can often carry diseases, and when bitten, the victim can contract that disease. Recent research suggests that the stripes of a zebra are used to ward off disease bearing horseflies (seen on the right). But how?

Well, although insect eyes are really neat to look at, they aren't the best eyes in the animal kingdom. The design of their compound eyes has a major defect: the arrangement of the lenses causes the image to appear in segments (it isn't one whole image like what we see, it's more like looking through a net). As a result, flies often have difficulties interpreting light - and the stripes of a zebra make it even tougher (the white on a zebra is not reflected by polarized light the same way as brown or black (which are reflected). The stripes basically confuse the fly. Although this has all been supported quantitatively through experiments, the impact the stripes have on the fly is still a bit cloudy.

Zebras could use their stripes as camouflage in the right terrain, like tigers do when hunting (stripes help to break up the shape of the animal, making it much more difficult to detect). In addition, since every zebra will have a different pattern, scientists suggest that they can be used for recognizing family members. The stripes are also suggested to affect the depth perception of predators, ultimately making them harder to catch.

The eighty-eight and eight-nine butterflies exhibit one of the most bizarre patterns in nature, and one of the most puzzling to scientists. There are different species, which may have different colours, or different concentric markings (which produce the "numbers"). But why have such an odd marking?

Adaptations are well studied in ecology, and are typically only long-lived if there is some sort of benefit to the organism (whether direct or indirect). It is unclear what these bizarre markings are for, but our best guess, for now, is that they are involved in the social ecology of the organism. (It may be used as a mating display, a way to recognize family, and so on).

A unique characteristic that some of these butterflies possess, is the ability to hear. They have what is known as a Vogel’s organ, a tympanal based auditory instrument (i.e. similar to an ear), that is located at the base of the forewing. An odd place for an "ear", nonetheless!

Unusual Creatures

This month will be very brief examples of weird-looking creatures. I'm going to try and shorten them up considerably. The picture displays the organisms that I have chosen. :)

The Mexican Axolotl, is a critically endangered species of salamander that is found in a southeastern wetlands of Mexico. Fewer than 100 individuals exist in the wild, yet they come in all sorts of varieties.

The white one on the left is an albino (common), and the red structures are external gills used for respiration (a close-up of the gills can be seen in the top-right photo). Usually salamanders, and other amphibians, lose their gills when they grow into an adult, but the most interesting thing about this axolotl is the reason its gills have been retained.

The mexican axolotl is a neotonic salamander - this means that it never completes metamorphosis. As a result it keeps the tail fin and external gills from its juvenile stage. In other words, the metamorphosis is blocked (by a thyroid hormone), but at the same time the organism can still mature into an adult! (If it was unable to mature, then the organism would be unable to reproduce, and would go extinct).

The star nosed mole (bottom photo) looks similar to any ordinary mole (top photo). The big difference is its strange nose, which consists of 22 ultra sensitive, fleshy tentacles. These tentacles aren't just for show, though.

Moles are blind, so they need powerful sensory systems in order to travel and hunt successfully. The nose of the star nosed mole is one of the best; containing up to 160 000touch sensors per square inch! The tremendous sensitivity of the star nosed mole allows it to hunt successfully both underground, and underwater! For underwater hunting, there is an incredible mechanism that is used to locate prey. This mechanism can be seen in the following video:

If you want more description on how this fascinating nose operates, the following link has a video that goes into more detail:

http://animal.discovery.com/videos/fooled-by-nature-star-nosed-mole.html

There are two species of Proboscis monkey, and both are critically endangered. Proboscis monkeys are endemic to an island called Borneo; this means that they are not found anywhere else on Earth.

Proboscis monkeys are sexually dimorphic; meaning that males and females are significantly different in appearance (think of how male peacocks have colourful feathers, whereas females don't). A male proboscis monkey (seen on the right), has an enlarged nose, and an odd row of fur around its neck that sort of looks like a lion's mane. Like male peacocks, the physical attributes of male proboscis monkeys are used to attract females (seen on the left). So, believe it or not, but female proboscis monkeys actually find the grotesque nose of the male to be attractive!

Another interesting feature of proboscis monkeys is the fact that they often have webbed toes (likely because regularly swim). Here is a video that provides some insight into the life of a proboscis monkey:

Puss moth caterpillars - as well as the adult moths - come in a variety of shapes and colours. Not only are they one of the more bizarre looking caterpillars, they are also one of the more dangerous, too!

Although this chubby, green caterpillar appears to be friendly ("smiling" in the photo on the left), it's one caterpillar you might not want to mess with. The top right photo shows the defensive posture it enters when disturbed: They rear up, and extend red flagella from their twin 'tails'. But it doesn't end here...

If their defensive posture is ignored, the caterpillars will squirt formic acid from their flagella! If you happen to come any caterpillar with twin 'tails' (clearly seen in the large photo on the left), don't touch it. If you are stung by one of these critters, it will leave a mark and you'll be in pain for several days.

The adult of this green, puss moth caterpillar can be seen on the bottom right. It poses no threat, I just added it because it's wings have a neat pattern.

Suggestions / Requests

Suggested by Charity : Frog Metamorphosis

The top-left picture shows an adult frog, if you follow the pictures around clockwise, this is the typical lifecycle of a frog (note that these are not all the same species). If you don't want to read this all, then here's a fun video to watch:

(Top-center picture): In the Spring, female frogs lay batches of gelatinous eggs (called "frogspawn"). Frogspawn can be laid in water, or on land as long as the air is humid enough to prevent desiccation (drying out).

(Top-right picture): The eggs that started off as a black speck in the core, have begun to develop into tadpoles.

(Bottom-right picture): Approximately one week after fertilization of the eggs, tadpoles will have developed and hatched. Tadpoles differ from adult frogs in several important ways: Tadpoles have a tail, no limbs (early on), and instead of lungs, tadpoles have external gills (covered in a gill sac).

(Bottom-center picture): After 6-9 weeks, tadpoles develop hind legs, and their gills are replaced by lungs! As a result, they must swim at the water's surface to breathe (no more gills to filter oxygen out of the water).

(Bottom-right picture): Forelegs begin to develop, the tadpole is now called a "froglet" (or in the case of toads, a "toadlet"). Shortly after forelegs develop, the tail will begin to disappear.

(Top-right picture): Metamorphosis is complete - the product is an adult frog complete with lungs, legs, and lacking a tail. After about 3 years, adult frogs attain the ability to reproduce.

You might be wondering what dictates the transformation from one stage to another? Well, thyroid hormones work together to speed-up, or slow-down the rate of development. These hormones respond to the environmental conditions, so if food or temperature are not right, the hormones can slow-down metamorphosis. On the other hand, if the environment is suitable, hormones will speed up development.

Last thing I want to say, is just an interesting fact: Not all frogs go through a tadpole stage. An example is the common coqui, which lacks a tadpole stage, and instead, hatches from an egg as a froglet.

    Suggested by Jesse: Venus Flytrap

Most, if not all of us have heard of the infamous Venus flytrap (Dionaea muscipula). It is only one species of carnivorous plants, out of a total of over 600!

Although there is only one species of Venus flytrap, horticulturists have developed many cultivars (varieties) of the species. Some venus flytrap cultivars can be seen in the photos on the left. They can have varied trap sizes, trap positions (vertical, horizontal), colours (all red, all green, mixed), and varying cilia lengths (cilia are the teeth projecting from the trap's rim).

So, we all know WHAT the Venus flytrap does, but HOW does it do it? The following video explains if very nicely:

  

If you want more detail on the trap's operating mechanism the following link goes into more cellular detail:

http://www.botany.org/carnivorous_plants/venus_flytrap.php

Venus flytraps don't only eat flies, though. Larger insects, spiders, and even frogs have been observed to be trapped within a Venus flytrap (see photo - this frog was lucky enough to escape). Venus flytraps are so successful at what they do, that there are even marine organisms that mimic its design! For instance, the Venus flytrap anemones (bottom-right photo) have "molecular blueprints" that are comparable to those of the Venus flytrap.

Defenses

Recap: Ok, so last month I gave some general information about different foxes, in the hopes to exemplify their extreme adaptability. It’s rare to find a terrestrial carnivore that is so widely dispersed, simply because it’s capable of adapting to so many different environments (You certainly won’t find wolves, or many other fair sized carnivores surviving in urban environments!). The broad niche of foxes makes them highly important ecologically, and of course, they’re adorable, too! But, enough about foxes! =P

This month I will be giving some examples of really cool adaptations that allow an organism to defend against predators. I’ll be giving examples of chemical, behavioral, physical, and “other” defense mechanisms. I’ll start each off with some well-known and obvious examples, but I will be giving and discussing my favorite examples which I’ve studied in class, or through reading. I will try to incorporate a plant example each week, but at the moment I basically know nothing about botany and don't have a lot of time to research, lol.This Sunday will be chemical defenses, and I have three very interesting examples! So stay tuned… ;)

Chemical defenses are quite common in animals, and are generally very effective. We all know of some chemical defenses: venoms in spiders, snakes, etc., squid ink, a skunk’s musk spray, and so on. But I want to give three interesting and less obvious examples:

1) Horned lizards (Phrynosomatidae – bottom right photo) have a haunting chemical defense called autohaemorrhaging. Basically “autohaemorrhaging” means that they can intentionally make themselves seep, or in the case of the horned lizards, squirt blood. This defense is extremely rare, but is also seen in a few insects and snakes.

Here is a video that shows a horned lizard putting its chemical defense to the use. It’s not as disgusting as it sounds; it’s actually really cool!

                                            


2) Bombardier beetles (Stenaptinus insignis – top right photo) can be found in Africa, Australia, and other subtropical locations. Their defense involves expelling boiling chemicals from its abdomen:

- enzymes and chemicals are contained within a specialized chamber located in the beetle’s abdomen.

- reaction takes place just before expelling – the beetle doesn’t want to have boiling chemicals inside it continuously… So enzymes catalyze the reaction as it leaves the beetle’s abdomen.

Reacton: Hydrogen peroxide is broken down by an enzyme called “catalase”, and 
hydroquinones are then oxidized by an enzyme called “peroxidase”. Reaction is exothermic (generates heat), producing chemicals at temperatures as high as 100˚C!

More info, and the beetle in action in the following link:

3) Chemical defense in plants:

- because plants are sessile (rooted in place and unable to move), defenses are necessary to prevent the organism from being more than just a “free-lunch”. Plant populations would be wiped out very easily, were it not for their defenses (allows only specific herbivores to eat them).

- toxins, irritants, pheromones, and other compounds provide chemical defenses. Pheromones are particularly fascinating because in some species of plants, they attract the natural predators of the organisms feeding on the plants. In other words, say a caterpillar is happily nibbling away on a plant… the plant will expel pheromones to attract a bird or some other animal that normally eats the caterpillar! =P

- common examples of chemical defense in plants include: poison ivy (irritant), milkweed (bad tasting chemicals), and believe it or not, tobacco (shown in picture on left).

The nicotine in tobacco may help to drive a human’s addiction, but to most insects, it’s a deadly neurotoxin potent enough to cause paralysis and even death! Just something interesting to think about next time you smoke a cigarette, lol.

You’ve probably heard of “playing possum” – well that comes from a behavioral defense in the Opossum, which plays dead when threatened. Behavioral defenses are highly unique, and are BY FAR my favorite type of anti-predator adaptation. Some common, well-known examples include: fish that puff up, color changes, and threatening stances intended to ward of predators. Here are a few interesting examples, which I quite like:


There are some extraordinary evasive defenses in lizards. We’ve all heard of flying squirrels, well, how about a flying lizard?! Draco volans, the “Flying Dragon”, (or “Flugdrachen”, in German) can be seen in the top-right photo. It looks like a lizard from prehistoric times, except downsized. Large, loose, and beautifully colored flaps of skin on each side of its body act as temporary wings, and are supported by
long ribs. The ribs can move and be stretched out sideways to help control flight. Here's a video of Draco volans in action:

Another extraordinary evasive defense is exhibited by Sailfin Lizards and Basilisks… (seen in the left photo). Some of these Hydrosaurus species can miraculously sprint across water to escape predation! If you want to check it out here is a video:

There are three steps to the lizard’s sprint; the “slap”, the “stroke”, and the “recovery”. During the “slap” phase, the lizard’s foot goes straight down, displacing water and creating a pocket of air around the foot; the upward force generated by the slap is enough to keep the lizard’s body above the surface while it kicks its leg backwards. This is the stroke phase, and generates the forward momentum. Finally, the recovery phase occurs when the foot is pulled up and out of the water ready for the next “slap” phase. As long as it runs fast enough, the lizard stays upright by pushing sideways with its feet (when necessary). The same idea generally applies when you’re swimming; you have to keep moving to remain buoyant. Also, if you doubt the validity of the “slap” phase, then try “slapping” the water next time your at a lake (you should be able to feel the upward force being generated).


The last example I have is a bird called a water dikkop (Burhinus vermiculatus – bottom-right photo). It nests on the riverbank, at sites where female Nile Crocodiles also have territory. This may seem like a bad idea, but this behavior actually helps the dikkop out! The crocodiles provide the dikkop, and their eggs, with protection from other large reptiles that steal from the dikkop’s nest. (It’s important to note that these thieving lizards are also common prey for the crocodiles). The water dikkop is generally nocturnal, so when it is active at night, and danger is imminent, the bird will send out a “burglar alarm” to that is believed to alert the crocodile of the trespassers. When in danger, the dikkop also lowers its head, spreads its wings, and charges the attacker (can be seen in the photo). Whatever it lacks in size, is compensated for by this birds immense courage. =P

I wanted to just mention that there are a lot of other behavioral defenses, including predator satiation and very elaborate ones in plants… I’ll explain these more in-depth another time (with examples), but that’s all that I have for you this week. =)

Physical Defenses come in all sorts of varieties:

1) Shells that act like body armor. Very common in mollusks (snails, crabs, etc), insects, and reptiles like turtles. Even some plants such as coconuts, and some nuts. (Picture on far left shows an Alaskan King crab hobbling amongst a “bed” of developing polyps - black). 

2) Protrusions extending from the body are another common defense. Examples include porcupines (see the little guy on the top right - contrary to popular belief porcupines cannot "shoot" their quills), sea urchins, tusks, and the spines/thorns on plants such as hazelnuts (see top right photo), acacia trees, cacti and so on.

3) This is the only example that I will actually go into detail this week, just because I don’t have time for three. But this one is really cool, so I had to do it. There’s a group of fish called “Parrotfish”, and some species have an interesting physical defense. First of all, they’re called “parrotfish”, because their teeth have fused into beak-like structures that are specialized for feeding on filamentous algae. Now onto the defense:

Species such as Chlorurus bleekeri, the Bleeker’s Parrotfish, secrete a “cocoon of mucus” around themselves when they go to sleep. (The Bleeker’s Parrotfish can be seen snoozing in a mucus bubble in the bottom right photo). The mucus is secreted from special glands in the fish’s opercular cavity (chamber containing the gills), and becomes gelatinous after coming in contact with the water. It can take up to 30 minutes, but once the cocoon has been secreted, the fish is protected from predation in a few ways… First, many nighttime predators hunt by smell, so the cocoon prevents these predators from detecting the parrotfish’s scent. In addition, the mucus cocoon is an excellent deterrence against predators who hunt with echolocation (emitting sound waves, then interpreting the surrounding environment by analyzing the rebounding echoes). When incoming echoes hit the mucus bubble, they bounce off in unpredictable directions, causing them to either be ignored by the predator, or to just confuse the hell out of the predator.





This week I want to give a few examples of "complex" defenses. Not that they're difficult to understand, it's just that they can't really be stringently classified into just being a "physical", "chemical" or "behavioral" defense mechanism. Anyways, here are two really interesting examples:

The first one is an interesting defense exhibited by anemonefish (also called clownfish; if you’ve seen Finding Nemo!) Here’s a video that explains it better than I can:

(Coleman's shrimp (protected by a shell, instead of mucus), and some other fish are beginning to develop this defence as well, which is interesting because these symbioses are still quite baffling).


The second is one of my favorite plant examples, Mimosa pudica (bottom-right photo)!

This plant is more sensitive than the one in the next video:

Close-up shot of less sensitive plant:

It isn’t rare to see plants that close up at night, because it makes sense (if photosynthesis minimal or not occurring, why not take a break?). But in the case of this plant, it also closes up in response to physical contact, as well as heat. There is an advantage to this; this phenomenon is a defense mechanism. When herbivores brush are eating a plant, and brush up against surrounding parts that they aren’t eating, the leaves will close up. This results in a “wilted” appearance, and the plant is no longer desirable to the herbivore, and so, the herbivore will move on to another plant. Apparently these plants are very inexpensive to have in your garden; however they are not at all easy to find.


Hopefully you found these defenses as interesting as I did, and have learned from and/or enjoyed this month’s “theme” of defenses. It is important to note that there is a plethora of really cool examples out there, and in nearly all cases predators have developed ways to overcome their prey’s defenses. There are also other types of defensive mechanisms that I did not mention (mostly because I know nothing about them… yet…) For instance, some animals use auditory defenses sounds that warn their friends, or their enemies (examples: rattlesnakes, and some birds). Others animals simply just prevent themselves from being detected (I’ll do camouflage and mimicry at some time in the future).

Foxes

The "theme" for March is foxes, just because they're my absolute favorite; they're so damned cute, and very interesting! There are three different species of foxes in the photo above: 

foxes here: the Red fox, the Swift Fox, the Arctic fox, and (my personal favorite) the Fennec fox. =) 

Note that there are other fox species that I have not shown here, for instance, the bizarre Tibetan Fox which has a odd square-shaped head!

The Fennec Fox is the smallest of all foxes, lives in the deserts of North Africa, and is generally nocturnal. You might wonder why they have such big ears - well, they aren't only for hearing... Fennec foxes have highly vascularized ears, and the large surface area allows blood to cool off faster (which helps them adapt to high desert temperatures). In addition, their fur has a special coating which protects them from the sun, but their fur is thick enough to keep them warm at night. Fennec foxes have hairs on their feet, which help them tolerate the high temperatures of the sand. 

Foxes are commonly domesticated as exotic pets, and the fennec fox is my personal favorite for two reasons:

1) it is very small

2) it lacks the musk glands present in other foxes (musk glands are sort of like the glands in skunks, except the smell is not as unpleasant).

Some characteristics of the fennec fox, have industrial applications. For instance, this video shows the applications of the fennec foxes' fur in sport equipment:

Arctic foxes live in the circumpolar regions of the Arctic, where environmental conditions can be highly variable between seasons (cold winters, and long summer days – sometimes with periods of no sunset!). Consequently, Arctic foxes have developed several adaptations for winter and summer seasons in the Arctic Tundra.

For instance in the winter, temperatures can drop to -50˚C - so the arctic fox has short legs, a short snout and small rounded ears. These characteristics all reduce the amount of surface area it has for heat loss. The Arctic fox has a counter-current heat-exchange system in the legs, which ensures that blood returning to the body (from the feet) has been warmed up. This means that, although the feet must survive at a lower temperature than the rest of the body, heat is not lost from the core of the body! The Arctic fox has very thick fur (the warmest of all arctic animals!), and its fluffy tail is used like a blanket. The white coat of the Arctic fox helps to reduce detectability by predators and prey during the winter. In the winter, when prey can be scarce, they tend to scavenge food left by polar bears. Unfortunately, these leftovers would depend on a good hunting season for the polar bears – which, due to global warming, are having increasingly difficult times with hunting on melting ice.

In the Arctic summer, the environment warms up considerably - melting snow and allowing for short-term vegetative growth. Arctic foxes shed their thick white coats, and develop a thin and dark summer coat. The molting (shedding) process can be seen in the pictures shown: Starting at the top-middle picture is the winter coat, follow clockwise around, and the summer coat can be seen on the bottom-middle - this is the Spring molting (preparing for Summer). If you continue clockwise back up to the top-middle picture, this is the Fall molting (preparing for Winter). The easiest way to monitor the molting is by paying attention to the facial features of the fox, as it will be indicative of what coat is developing. In the summer, when prey is abundant, Arctic foxes hunt and eat animals such as lemmings, voles, and arctic hares in the warmer months. If the Arctic fox is hunting successfully, it will store its foods in caches above the permafrost (it’s like using the lower level of soil - the permafrost, which is still frozen - as a freezer). The largest known arctic fox niche contained 38 birds, 4 rabbits, and nearly a dozen eggs! On the other hand, if hunting is poor Arctic foxes are content eating berries and birds’ eggs.

Arctic foxes are highly adaptable predators; however are susceptible to being threatened by global warming in the future. Although Arctic foxes may be more tolerant to global warming, some of the other species that they rely on are not (such as polar bears). Global warming is particularly problematic in the Arctic because when it warms up the permafrost, it releases more greenhouse gases into the atmosphere ultimately increasing the effects of global warming (positive feedback).

The phrase “as cunning as a fox” comes with good reason – the red fox is one of the most cunning members of the animal kingdom – capable of outwitting and outmaneuvering both predator and prey. Like other species of foxes, the red fox also uses its tail as a blanket when cold. But, its tail also acts as a signal flag to communicate with other foxes! For example male foxes (called dogs) use it as a mating signal towards female foxes (called vixens). They also use their tail to warn other foxes of nearby danger or prey.

Despite its name, the red fox can have many different coats (bottom-right photo). This is due to non-deleterious genetic mutations, which lead to multiple variants of coat colorations and patterns. In fact, pups from the same litter can even have different coats.

Because of its extreme adaptability, the red fox has the widest geographic range for any Carnivora member and it can even be found in urban communities (especially in Europe). As a result, it can pose problems when it is introduced into an alien ecosystem.

Although cute, red foxes are often pose threats as vectors (transmitters) of diseases. This is especially true in Europe, where red foxes often carry rabies. Another less common disease is “mange” – seen in the top-right photo. Mange occurs when the fox is infected with a parasitic mite, Sarcoptes Scabiei, and is characterized by loss of hair and self-inflicted wounds. Because the mites prefer skin with little hair, as the condition worsens more hair is lost and the mites are favored (look closely at the tail of the fox in the photo). The mite’s activity causes a reaction in the skin that makes the animal bite and scratch constantly - self-inflicting open wounds and secondary bacterial infection often follow (see the rear legs of the fox in the photo). A fox suffering from mange will often act abnormally. Some strains of the parasitic mite are infective of humans and most pets; so if you see a fox that is losing hair, biting itself, or exhibiting odd behavior, it’s best to stay away from it! =P

Unlike most mammals, the red fox is able to hear low-frequency sounds. A fox’s hearing is sharp enough to detect the squeaking of mice from as far as 100 meters! Below is a video that portrays a beautiful hunting technique and incredible hearing of the red fox. =)

That's all I have to say about foxes... for now! :)

Animal of the Week - Intro

This blog is here mainly for fun. I want to share my interest in plants and animals with you, and hopefully show some cool information that makes my posts worth spending time to read. Hope you enjoy, and feel free to comment, ask questions, or give suggestions! :)

If you build an appreciation for the Earth's flora and fauna, then you will be astonished by what's out there -- and how much else remains to be explored! =)