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Hello - Welcome. The purpose of this site is to document my experiences photographing wildlife and nature throughout Australia and abroad.  I hope you find the content interesting and educational, and the images  cause you to reflect on how important it is preserve natural places and their inhabitants.

For me photography of the natural world is more than just pretty settings and cuddly animal photos. It's a concern for the environment and the earth all living creatures must share.

Note that images appearing in journal posts are often not optimally processed due to time constraints.

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Friday
Nov212014

Why Do Zebras Have Stripes

Africa is the repository for a number of remarkable animals; however, the black and white striped Plains Zebra (Equus quagga), known locally as the tiger horse is often overlooked.   The reason why this particular animal is decorated with such a striking pattern of stripes, not observed in other hoofed animals, has often been discussed in scientific circles.

LEFT:  Plains Zebra (Equus quagga), known locally as the tiger horse (click to enlarge).

Wallace and Darwin

In the late 1800’s, Alfred Russel Wallace and Charles Darwin debated the striped pattern and proposed several ideas.  The main argument being that the alternating black and white stripes had evolved to act as a form of camouflage, by disrupting predatory attack by visually confusing carnivores.  A similar disruptive camouflage pattern is often used to paint naval ships and can be seen on military uniforms; the stripes tend to break up the outline of a solid object.  Another suggestion was that the stripes could act as a social mechanism; zebras live in herds of several or more individuals, while a third hypothesis was the possibility that striping was used as a mechanism for heat management - white reflects heat whilst black absorbs heat.

Flies and Body Hair

Recently, the conundrum was solved when a group of scientists discovered that stripes act as a deterrent to attack from horseflies and tsetse flies.  Although the exact reason to why flies find striped surfaces unattractive is not yet known, the reason to why zebras have stripes, in contrast to other hoofed animals was revealed.

For the most part African hoofed mammals have longish body hair that protects them from hungry-biting insects; the mouth parts of the flies are not long enough to penetrate the length of hair.  Zebras on the other hand have very short body hair and the skin is easily reached bythe  hungry blood-sapping flies.

To provide evidence to support the scientist’s hypothesis, biologists mapped the worldwide geographic distribution of zebra species, noting the thickness, location and intensity of striping, within a range of variables such as: temperature, predators and habitat.   They then mapped the distribution of horseflies and tsetse flies and examined the areas where variables overlapped.    The results indicated that zebra striping was more pronounced, thicker and darker in areas of overlap.  Furthermore, it was observed that striping was more pronounced during periods of high fly reproduction.

LEFT:  The pattern of stripes can be confusing to predators when the zebra is at the trot (click to enlarge).

Although some of Wallace’s theories may hold water in that there is a possibility that striping has other advantages, such as camouflage; this is not the evolutionary driver for striping.  It would appear that evolution, in zebra species, has selected black and white stripes as an effective means to combat insect attack.

References

 Caro, T., et al,. 2014, Function of Zebra Stripes.  Nature Communications  5, Article number: 3535

Video

The herd of zebra was captured in the Maasai Mara National Reserve, a large game reserve in Narok County, Republic of Kenya.  The 'Mara' is contiguous with the Serengeti National Park in Mara Region, Tanzania.  The video particularly shows the intensity of the striping.

Tuesday
Jul292014

Moray Eels - Diverse, Colourful and Photogenic

Morays eels may look fearsome and no doubt have intimated more than a handful of divers and snorkelers; however, to say they were dangerous animals would be misnomer. 

LEFT: Black-spotted Moray Eel, (Gymnothorax favagineus).  A large eel that reaches 2 meters in length, Indonesia (click image to enlarge).

Moray eels belong to the family Muraenidae and are cosmopolitan, meaning they inhabit tropical and sub-tropical seas globally.  Despite their snake-like appearance, moray eels are not reptiles but are fish that have evolved to inhabit a different niche to other fish species.  Morays are often the dominant predators within a community.

There are approximately 200 different species of moray eel that range in size from a few centimetres to 2 meters in length.  They have adapted well to their niche and most morays sport large eyes which enhance their light-resolving ability when hunting in crevices, caves, and at night. 

Moray eels have a narrow head, an elongated body which is slightly flattened towards the tail, and a lack of pectoral and anal fins leads to their serpentine appearance.  Their jaws are normally large with sharp incisory teeth.    The teeth of animal are usually a very good indicator to the prey it selectively hunts.

Moray eels are carnivores and the moray’s pointy teeth are ideal for capturing fish, crustaceans, molluscs and even other eels.   Although for the most part solitary, morays have been known to co-operate with other species such as cod, grouper, sharks and even ingenious spear fisherman to obtain food.  

Pharyngeal Jaws

An interesting evolution observed in moray eels are pharyngeal jaws .  Simply explained, morays have a second set of jaws in their throat that contain teeth.  When feeding these inner jaws can be projected into their mouth cavity whereby they grasp the prey and dislodge flesh before transporting the food into the back of throat and into the digestive system. 

LEFT:  Diagram showing pharyngeal jaws in moray eel.  Moray eels are the only animals that use pharyngeal jaws to actively capture and restrain prey  (diagram copyright).

Once the prey has been seized, the eel twisted onto itself to remove a bite-sized portion of food.  A moray eel does not have the ability to chew its food and swallow as do other fish.  Because of the narrow head, it is unable to create negative pressure used to swallow prey.  The pharyngeal jaws are therefore very important.

Skin

Unlike other fish, morays do not have scales.  To protect their skin they secrete a slimy mucus.  In some species the mucous contains toxins which provide self-defensive against other animals that may prey on the eel.  The slimy skin aids in locomotion (slithering into and out tight locations), makes it difficult for a predator to grasp the eel and, in some species assists in burrow-building.  Ribbon eels (Rhinomuraena quaesita) often live in sand burrows and the mucous is used to cement sand grains together to provide a solid wall for the burrow.

Reproduction

Interestingly moray eels are not live-bearing but are oviparous, which means that sperm and eggs are fertilized outside of the womb in the surrounding water. 

When morays spawn they release thousands of eggs which can develop into larvae which become part of the plankton that drift in the ocean currents.  After a year or so, the larvae mature and can swim the sea floor to join whatever community that maybe living there.

LEFT:  Whitemouth Moray Eel, (Gymnothorax meleagris).  An uncommon eel observed in Indonesia (click image to enlarge).

Undeserved Reputation

Their fearsome reputation (which is unwarranted) has been generated from the method they use to breathe (removing oxygen from seawater).  A moray must continually open and close its mouth to generate a current of water that is passed over small circular gills which are located toward the rear of the mouth.

Moray eels are not aggressive and if treated with respect will not attack a diver.  However, if you wave your gloved-finger in front of their face then expect a reaction – not because it’s a finger but because the waving action and colour resembles a small fish.  

LEFT:  Fimbriated Moray Eel, (Gymnothorax fimbriatus).  An eel not observed that often (click image to enlarge).  Photographically, morays are of interest due to their morphology, differing camouflage patterns and often kaleidoscope of colours. 

I can recall a dive in Japan when I was foolish enough to wave a non-gloved finger in front of a smallish, but brightly coloured dragon eel.  The result was not unexpected; the eel removed a large chuck of flesh from the side of my index finger.

I always keep a lookout for these fascinating creatures when diving, and if I see a moray, I stop and observe its behaviour and marvel at its evolution and often ornate and colourful markings.  

Tuesday
Feb112014

Where Have All The Fish Gone... Diving Weda Island, Indonesia

Four weeks SCUBA diving in Indonesia sounds like a good way to spend some time; however, swimming in an ocean devoid of anything larger than a sardine becomes worrisome in relation to the overall health of the reef ecosystem.

I was diving in the coral triangle in northern Indonesia based at Weda Island; a small island adjacent to Halmahera Island, the largest island in the northern archipelago, a region made famous by the nineteenth century naturalist Alfred Wallace and his discovery of the Standard-wing Bird of Paradise.  

Coral Triangle

The Coral Triangle is a geographical term referring to a rough triangular area of tropical water between Indonesia, Papua New Guinea and the Philippines.  The triangle encompasses two biological rich areas of marine biodiversity. 

LEFT:  Map of Coral Triangle  courtesy (www.rareplanet.com).  Click to enlarge.

Weda Island lies midway between the northern and southern regions; an area susceptible to strong currents, water transports large volumes of larvae which form the building blocks of a complex marine web and ecosystem.

Few Fish and Invertebrates.   Siltation from Mining Operations

I became concerned after completion of several dives in habitats from near shore to coastal coral platforms and deep oceanic drop offs.  There was something missing – FISH; in particular, anything larger than a “sardine”.  There also was a general lack of invertebrates.  It was as if the coral home was open but the inhabitants had left for the day...

Despite the lack of fish and critters, coral diversity on the outer reefs was excellent with massive and delicate corals growing from near surface to 30 plus meters.  Unfortunately, two Chinese owned mining operations have caused siltation on inner shore reefs and inshore corals are degraded.  So where were the reef dwellers?

Warm Water, Climate Change and Over Fishing

Certainly tidal currents and the moon phase can affect the presence of predators; however, I spent a month in this area and the results were the same for nearly every dive – very minimal fish life, poor invertebrate diversity, and no sharks whatsoever!  

In some areas the water was incredibly warm and the effects of temperature increase could readily be observed in some coral species in the form of bleaching.

The stress factor most commonly associated with bleaching is elevated sea temperature, but additional stresses such as high light intensity, low salinity and pollutants are known to exacerbate coral bleaching.  If the causal stress is too great or for too long, corals can die.

Reef corals are very sensitive to sea temperatures outside their normal range.  Elevated temperatures of 1 Degree Celcius above the long term monthly summer average are enough to cause coral bleaching in many dominant coral species.

When temperatures exceed threshold levels for long enough, the symbiotic relationship between the zooxanthellae and the corals breaks down and bleaching results. If stressful conditions prevail for long enough, the corals may bleach and die. However, if stressful conditions abate, then the bleached corals can recover their symbiotic algae and return to their normal, healthy colour. The severity of bleaching can vary substantially according to water depth, location and species of corals.

Is commercial over fishing, the local effects of nutrient run off from farming and industrial practices (mining), and perhaps the warming effect of global warming (current change and coral bleaching) beginning to be realized.

Crown-of-Thorns

Not seeing and watching fish, I did observe several Crown-of-Thorns starfish (Acanthaster planci) during my dives.  Although this species can reach plague proportions decimating corals (they feed on the coral polyps), the sighting of a few animals does not in itself present a problem.

LEFT:  Acanthaster planci is a large starfish that can consume live coral polyps at an alarming rate.  Click to enlarge.

The crown-of-thorns starfish (Acanthaster planci) is a coral eating starfish or sea star native to coral reefs in the Indo-Pacific region. They are named after the dense spines radiating from their arms and they belong to the same group as all starfish, sea urchins, sea cucumbers and brittlestars.

Crown-of-thorns starfish are an important functional species on healthy coral reefs. They feed on the fastest growing corals such as staghorns and plate corals, allowing slow growing coral species to form colonies, therefore increasing coral diversity.

Is it Too Late ?

I have been diving since the late 1970’s and can remember vividly the days when sharks did worry you, there were too many fish to see anything past a few meters and the corals were strongly coloured without showing the effects of bleaching.  

Is it too late?  Over the last ten years I’ve observed a downfall in many areas that were previously teaming with fish and other marine life.  Areas of Papua New Guinea, the Solomon Islands and parts of Australia that are “off the beaten track” and did have large number of fish now produce little…  

On another trip to Indonesia, I was very conscious that at night, several large fishing boat flotillas passed our live-aboard dive boat - stripping the reef of the very fish we had seen the day before…

I believe the years are numbered in which newly-minted divers will experience what was seen by earlier generations.  The over fishing, habitat destruction, lack of international pollution control, burdening populations in many coastal nations, and the need to feed people and profit from the oceans has taken its toll.

Whilst not every food species is directly affected, there is a flow-through effect that occurs when you remove one particular species from the chain, or reduce its numbers to near extinction (for example, sharks, tuna and predatory coral fish). 

The next decade will be decisive to the overall state of environment concerning the marine ecosystem.

Thursday
Oct102013

Meet the Thrombolites - Ancient Life in Western Australia

I’ve spent the last few weeks in Western Australia exploring some of the region south of Perth.  My main aim was to find and photograph a number of orchid species found only in the south west of the state amongst the vast stands of Karri, Tingle, Tuart and Jarrah forests.  I also was keen to photograph the ancient mound-like algal mats called thrombolites that are known to inhabit areas along the coastal zone.

LEFT:  Thrombolite community, Western Australia (click image to view larger)

Thrombolites and Stromatolites - Biology and Life History

Many individuals have heard of stromatolites.  These ancient organisms (prokaryotes) are partly responsible for release to the atmosphere of increasing levels of oxygen.  This oxygen slowly replaced the methane-dominated atmosphere prevalent during the Achaean Period.  The microbes that form thrombolites and stromatolites produce oxygen as a byproduct of photosynthesis and precipitate calcium carbonate (biogenic limestone) which create the slow-forming dome-like structures.  Thrombolite communities only occur in warm, shallow, hypersaline and well lit waters.  

Thrombolites and stromatolites are a major constituent of the fossil record for about the first 3.5 billion years of life on earth, peaking in abundance approximately 1.25 billion years ago before declining in abundance and diversity by the start of the Cambrian Period.  Declining diversity is thought to be primarily because of the increase in grazing-type animals, such as gastropods, that evolved from the beginning of the Cambrian Period.

Growth rates are slow and are around 10 cm per 100 years; but it must be remembered that only they outer layer of the mound is alive.

Modern thrombolites and stromatolites are uncommon.  Specific environmental conditions are needed for their long-term development which includes a high temperature and hypersaline environment where the occurrence of grazing creatures is minimal.

What are Thrombolites and how do they differ from Stromatolites

Thrombolites are clotted, accretionary structures, formed in shallow water by the trapping, binding, and cementation of sedimentary grains by biofilms of microorganisms, especially cyanobacteria.  They exhibit a coarse, clotted fabric and laminae, if present, are indistinct.
The stromatolites are similar, but are well laminated with the outer surface displaying small, discrete knobs.  

Both thrombolites and stromatolites precipitate calcium carbonate; however the former precipitates aragonite, a carbonate mineral which is a crystalline form of calcium carbonate.  

LEFT:  Cross section showing internal structure of thrombolite and stromatolite.

Rarity

Thrombolites and stromatolites are not common and are “Living Fossils”.  They provide a key to the past as their form, structure and biology has not changed since their heyday in the Achaean Period.

Casuality of their own Success

Plate tectonics, and the competition for space, took their toll on the primitive thrombolites.  They were eventually a casualty of their own success. Newly evolving organisms were thriving in the improved oxygenated conditions, and found the thrombolites to be a very tasty meal.  They were slowly eaten off the face of the Earth.

Their legacy however, is the Banded Iron Formations (BIFS) that are backbone of the mining industry in Western Australia.  BIFS form by the oxidation of iron locked in sediments and could not have occured without an oxygenated atmosphere for which the thrombolites and stromatolites were largely responsible.  

The Toyota Landcruiser I drive would not be a possibility if these amazing organisms had not evolved…

Glossary

Hypersaline – A water body that has a very high concentration of sodium (salt)
BP – Before present
Plate Tectonics – The movement of the outer part of the earth’s crust due to eaerth’s interior heat
Lacustrine – Lake
Laminae – Layers added above each other similar to a layer cake
Gastropods - Phylum Mollusca comprising the snails and slugs
Achaean Period – Geologic Eon ~4000 – 2500 million years ago
Cambrian Period – Geologic Period ~550 – 490 million years ago
Quaternary Period – Geologic Period ~2.5 million years ago until present day

Friday
Jun142013

Shingleback Crossing - Stop and Lend a Hand

Road kill is always on my mind when I travel in Australia.  More often than not, I see dead or maimed animals along the road verge; the by-product of modern, high speed motor transport.  The further one travels away from the city limits the more prolific road kill can become.  

LEFT:  A shingleback lizard is given a helping hand to cross a busy highway in South Australia (click for larger view).

On a recent trip to South Australia, the time taken to travel between points was longer than normal.  The culprit that was slowing my travel was a relatively small slow moving animal protected by a heavy armour of interlocking  pine cone-looking scales; it was the Shingleback Lizard (Tiliqua rugosa), often referred to as the pinecone or stumpy-tailed lizard.  

It appeared that every time I gathered driving speed, I’d witness yet another "pinecone" crossing the road.  Sometimes they would amble quite briskly across the centre-line, only to stop and raise their head, sensing the vibrations of an approaching vehicle, before doubling back into the direct line of the vehicle.  I was stopping several times within a few kilometres, to dismount and rescue these ancient-looking dinosaurian-looking reptiles.

Brief Natural History

Shingleback Lizards, the largest lizard of the Skink family, live alone for most of the year; however, between September and November reunite as monogamous pairs.  Shinglebacks are often seen crossing roads in pairs, with the male following the female; the same pairs may unite every year during the mating season.  With the life expectancy of a shingleback reaching approximately 20 years and the fact that they are monogamous, it’s important that individual lizards are not squashed unnecessarily into the bitumen by uncaring motorists.

Unique Facts - say no to"SEX" with your brother

One very interesting aspect of shingleback reproduction is the ability of the lizards to discriminate between kin and non-kin, even after being separated from their mothers after birth.  This observation has been scientifically tested by observing that they preferentially direct attention and tongue flicks to related over non-related individuals (Main & Bull, 1996).  The mechanism for this unusual ability is unknown, but probably involves olfactory cues.  Whatever the mechanism, not reproducing with your “brother or sister” has obvious genetic benefits and cannot be dismissed.

Reptiles are ectothermic meaning they derive their body warmth directly from the environment.  This is one reason why you never see reptiles during the winter months or on cold overcast days.  It's also another reason that you often see reptiles sunning themselves on the road verge; the bitumen is warm.  To aid in warming itself, the shingleback has the ability to arc and flatten its body extending its scales so that they present a greater surface area towards the sun.  An added benefit to this solar warming is defence; flattening itself the shingleback can appear larger in size.  The posture and size also mimics a highly venomous snake called the death adder.

LEFT: A meeting and mutual respect; a shingleback lizard (Tiliqua rugosa) is carefully carried across the highway (click for larger view).

Foraging Strategies and Navigation

Foraging strategies change throughout the year among sexes.  During the two months before mating males use a time-maximization strategy, while females use an energy- maximization strategy.  During mating when lizards are paired, the male eats significantly less than the female whose eating habits do not alter.  During this time the male maintains a distance of a few centimeters behind the female.  This behavior when paired, presumably suggests that males are on the alert for rival males.  Bull & Pamula (1998) discovered that females can detect danger far more quickly when paired than when alone, and when paired the female earlier when the male is feeding.  They suggested this behavior maybe an adaptation for identifying large predators, such as dingoes, feral cats and wedge-tailed eagles when plant food is only available at exposed locations.

A study by Freake (2001) found that the lizard can use celestial cues as a navigational strategy to return to its home range. It detects these cues using its parietal eye, perhaps functioning as a celestial compass.  

Not a Klutz

If you have read this far, you’ll realize that the Shingleback is not just a slow-moving armoured klutz, but a marvel of evolutionary design.  Therefore, the next time you see a "pinecone" crossing the road, give way to the shingleback.  Better still, stop your vehicle and give the lizard a helping hand.