|Paper Nautilus hunt is on!
Autumn and winter is a great time to find Paper Nautilus shells on the beach, but you must be up early to beat the birds to an intact prize.
Only the female of the species, like all argonauts, creates a paper-thin eggcase that coils around the octopus. The shell is gas filled and is used as a brood chamber to keep the young ones safe.
Females grow to 100 mm, while males do not exceed 20 mm Males reach sexual maturity at a mantle length of 8 mm and often resides inside the females shell.
The Nautilus is occasionally involved in mass stranding’s along the South African coastline. The stranding’s are seasonal and generally occur between April and August, towards the end of the animals' spawning season, look out for favourable tide conditions and an onshore wind onto a long deserted beach.
Enjoy the hunt
What type of Crab is that?
It’s not often that I come across something that baffles me on the sea shore, and so I lay down the challenge to my hiking guests to ask questions about our environment and if I don’t know the answer my promise to them is to find out and get back before the end of the trail or via e-mail. This bold statement has put me in some difficult spots often taking months to get to the bottom of the mystery but this is after all the best way to learn.
The other possibility is we may stumble upon a new species which is not as unlikely as one would think! Science has identified some 2 million species, scientists estimated there are millions more left to discover, and new species are constantly being discovered and described.
Unfortunately this is not new and can’t be named the Blue eyed Beachcomber! This is the megalopa larval stage of a crab – the last stage before it moults into a juvenile that looks like the adult stage. The give-away is the abdomen, which is still segmented and relatively large. It is still difficult to pin down the species, either army crab Dotilla fenestrata (from the general shape), or Columbus' crab Planes minutus, which does have short blue eyes (and a blue body) in the adult stage.
Big thank you for the help towards identifying this little guy.
It makes me shiver when I hear people propose street lights for Pearly Beach, under the misconception that it will help stop crime.
"Better lighting by itself has very little effect on crime."
Lighting improvements are in general more likely to have a positive impact on the public's fear of crime than on the incidence of crime itself.
In fact the criminal is more likely to benefit from improved street lighting, and if observed or disturbed disappearing into seemingly now much darker areas.
I am not a tree hugging, bunny loving environmentalist but I do understand the critical value of the natural world, having extensively studied ecological systems, specifically in this area.
The negative effects
Most of humanity lives under intersecting domes of reflected, refracted light, of scattering rays from over lit cities and suburbs, from light-flooded highways and factories. In most cities the sky looks as though it has been emptied of stars, leaving behind a vacant haze that mirrors our fear of the dark, and yet above the city's pale ceiling lies the rest of the universe, utterly undiminished by the light we waste—a bright shoal of stars and planets and galaxies, shining in seemingly infinite darkness.
It was once thought that light pollution only affected astronomers, who need to see the night sky in all its glorious clarity, but like most other creatures we also need darkness. Darkness is as essential to nature's biological welfare, as much as light itself.
We are only just understanding the consequences of our meddling with the natural world and only just realising that we are fundamentally connected to it!
From the human perspective for the past century or so, we've been performing an open-ended experiment on ourselves, extending the day, shortening the night, and short-circuiting the human body's sensitive response to light. The consequences of our bright new world are more readily perceptible in less adaptable creatures living in the peripheral glow of our prosperity.
Nocturnal mammals such as Cape Grysbok browsing more cautiously under the permanent full moon of light pollution because they've become easier targets for predators. Insects cluster around streetlights, and feeding at those insect clusters is now ingrained in the lives of many bat species. Our local bat species potentially could be ousted by a light-feeding species, despite the fact that moths, a major nocturnal pollinator in the fynbos kingdom would be the predominant species attracted by the light and therefore the predominant predated species, potentially reducing fynbos diversity.
Could we loose the common Spotted thick-nee or the seldom heard Fiery-necked nightjar nocturnal chorus?
In a very real sense, light pollution causes us to lose sight of our true place in the universe, to forget the scale of our being, which is best measured against the dimensions of a deep night with the Milky Way—the edge of our galaxy—arching overhead.
Expanding our Perception
We live in an amazing world of limited perceptions, viewing our world with sense organs and a nervous system that are equipped to perceive and understand only a small middle range of sizes, moving at a middle range of speeds. Outside this range even our imagination is handicapped, and we need the help of instruments and mathematics. This tiny comfortable range of sizes, distances or speed is set in the midst of a gigantic range of the possible, from the scale of quantum strangeness at the smaller end to the scale of cosmology at the larger.
We call light, visible light because it is the narrow band of wavelengths we can perceive but wavelengths stretch much further than humans can detect. radio waves, micro waves, infrared, ultraviolet, x-rays and gamma rays are all undetectable to us but some so called invisible wavelengths are essential to many animal species, some insects see flowers in amazing ultraviolet and some birds use ultraviolet for hunting and breeding, some snakes and vampire bats locate prey using in infrared, even the sounds we hear or more correctly the mechanical wave of pressure or displacement through either air or water is a fraction of the range of ultrasonic frequencies that are picked up by other species of animals, dolphins and again bates use ultrasonic eco location to navigate and hunt and elephants and whales use ultrasound to communicate to name but a few. Our olfactory perception or sense of smell detects a fraction of what's on offer (probably just as well) some animals are many thousand times more sensitive to this strange world of complex messages and signals lingering long after the messenger has moved on.
We have science to thank for drawing our attention to these wonders some beyond our wildest imagination, this ever expanding perception of our world and universe around us certainly is more than we can perceive unaided. What a wonderful time to be alive!
Spirals maths and everything
Fibonacci is the smart guy that introduced our modern day numerical system (Arabic numerals) in 1202, replacing difficult Roman numerals, he also introduced to Europe a sequence of numbers later known as Fibonacci numbers, although this number sequence was known to Indian mathematicians as early as the 6th century. This mathematical equation now called by many names most popularly the golden ratio has been studied for centuries and used to analyse the proportions of natural objects from our spiral universe to DNA and most things in between also man-made systems such as financial markets, art and architecture. In fact if you look for the Golden ratio you will find it everywhere!
But why is this natural spiral re-occurring?
Could it be influenced by our incredible trajectory through the universe?
The standard image of our solar system is not exactly correct.
The sun is like a comet travelling at 70,000km per hour, our planet and the others in our solar system are dragged along in the sun's wake by gravity, all the time each planet rotates clockwise around the sun in their varying orbits.
The story doesn't end there, our Milky Way travelling at 828,000 km per hour has 100 to 200 billion suns rotating in its wake! Not to mention there are 200 billion other known galaxies many of which are spiral like ours.
Could it be that in the non-spiral galaxies the maths is different?
Barnacles are often overlooked but a short trip into the life of these varied and advanced creatures tells a different story.
A barnacle is a type of arthropod in the subphylum Crustacea, and is hence related to crabs and lobsters. Barnacles are exclusively marine, and tend to live in shallow and tidal waters. They are sessile suspension feeders, and have two larval stages.
Free-living barnacles are attached to the substratum by cement glands that form from the base of the first pair of antennae; in effect, the animal is fixed upside down by means of its forehead. In some barnacles, the cement glands are fixed to a long muscular stalk, but in most they are part of a flat membrane or calcified plate.
Barnacles are displaced by limpets and mussels, who compete for space. They also have numerous predators. They employ two strategies to overwhelm their competitors: "swamping" and fast growth. In the swamping strategy, vast numbers of barnacles settle in the same place at once, covering a large patch of substrate, allowing at least some to survive in the balance of probabilities.
Most barnacles are hermaphroditic, The ovaries are located in the base or stalk, and may extend into the mantle, while the testes are towards the back of the head, often extending into the thorax.
The sessile lifestyle of barnacles makes sexual reproduction difficult, as the organisms cannot leave their shells to mate. To facilitate genetic transfer between isolated individuals, barnacles have extraordinarily long penises. Barnacles have the largest penis to body size ratio of the animal kingdom.
Yellow-rimmed goose barnacles , also called stalked barnacles, filter-feeding crustaceans that live attached to hard surfaces of flotsam. A medieval myth was these barnacles grew into Barnacle Geese, in the days before it was realised that birds migrate, it was thought that Barnacle Geese, Branta leucopsis, developed from this crustacean, since they were never seen to nest in temperate Europe, hence the scientific and English names. The confusion was prompted by the similarities in colour and shape. Because they were often found on driftwood, it was assumed that the barnacles were attached to branches before they fell in the water.
The buoy barnacle Dosima fascicularis, , is "the most specialised pleustonic goose barnacle" species. It hangs downwards from the water surface, held up by a float of its own construction, and is carried along by ocean currents.
Whale barnacles are barnacles belonging to the family Coronulidae. Whale barnacles attach themselves to the bodies of baleen whales during the barnacles's free-swimming larval stage. Though often described as parasites, the relationship is an example of obligate commensalism, as the barnacles neither harm, nor benefit, their host.
Microscopic Aquatic Life
Marine microscopic life is incredibly diverse and still poorly understood. For example, the role of viruses in marine ecosystems is a field barely explored to date and will undoubtedly unveil many secrets as this field opens.
The role of phytoplankton is far better understood due to their critical position as the most numerous primary producers on Earth. Simply put Phytoplankton serve as the base of the aquatic food web (excluding seaweeds and algae) providing an essential ecological function for all aquatic life. One of the more remarkable food chains in the ocean because of the small number of links is that of phytoplankton feeding krill which is then predated on by baleen whales.
Phytoplankton obtains energy through the process of photosynthesis and must therefore live in the well-lit surface layer of an ocean, sea, lake, or other body of water. Phytoplankton account for half of all photosynthetic activity on Earth and importantly are responsible for much of the oxygen present in the Earth's atmosphere more than half of the total amount produced by all plant life, In a way the Amazon rain forest is less critical to us than this diverse group of aquatic photoautotrophic microorganisms. There are about 5,000 species of marine phytoplankton. But figures state phytoplankton is in decline by 1% per year probably due to a combination of global warming and acidification of our oceans.
The next level of plankton in the aquatic food web is Zooplankton many are too small to be seen individually with the naked eye. Included in zooplankton are many juvenile species of jellyfish, molluscs and even fish as well as crustaceans such as copepods and krill. Planktonic copepods (usually the dominant members of zooplankton) are important to global ecology and the carbon cycle, by feeding near the surface at night, then sinking into deeper water during the day to avoid visual predators, their moulted exoskeletons, faecal pellets and respiration at depth all bring carbon down to the deep sea. This vertical migration and therefore carbon sinking is also displayed by Krill. The surface layers of the oceans are currently believed to be the world's largest carbon sink, absorbing about 2 billion tons of carbon a year, the equivalent to perhaps a third of human carbon emissions!
Zooplankton is a wide and abundant group of animals and are primarily transported by ambient water currents, however some have the power of locomotion and use this to avoid predators. Zooplankton feed on bacterioplankton, phytoplankton, and other zooplankton (often cannibalistically), detritus (or marine snow). Zooplankton form a vital role in the aquatic food web both as predator, scavenger, filter feeder and of course prey to many fish species, filter feeders, whales and even birds.
Disturbances of an ecosystem resulting in a decline in any of these micro organisms can have far-reaching effects. We are only beginning to understand the connectivity between ourselves and our natural environment and the vital role we must play in changing our ways, not for the environments sake but for our own survival. The way forward is simple live sustainably.
Cape Clawless Otters
These delightful creatures are abundant on our coast yet few people have seen them.
What is relatively easy to find is signs of them having passed by the previous night, leaving clear tracks in wet sand or mud. To identify the track the clue is in the name, a large clawless track often in pairs with occasional tail drag marks. Almost every trail I guide I’m able to point out the tell tail tracks to delighted visitors to the area.
Cape Clawless Otter or Groot Otter, is the second largest freshwater species of otter. African Clawless Otters are found near permanent bodies of water. They range through most of sub-Saharan Africa, except for the Congo basin and arid areas. They are characterized by partly webbed and clawless feet, from which their name is derived.
African Clawless Otters have thick, smooth fur with an almost silky underbelly. Chestnut in colour, they are characterized by white facial markings that extend downward towards their throat and chest area. Paws are partially webbed with five fingers, and no opposable thumbs. Adults are 160cm in length including tail, weighing 10-21kg.
They will only be found within reach of fresh water which is deceiving because their nocturnal wanderings can be extensive. Logs, branches, and loose foliage greatly appeal to the otter as this provides shelter, shade and great rolling opportunities. Slow and rather clumsy on land, they build burrows in banks near water, allowing for easier food access and a quick escape from predators. The diet of Aonyx capensis primarily includes water dwelling animals such as crabs, fish, frogs, and worms. They dive after prey to catch it, then swim to shore again where they eat. Their hands come in handy as searching devices and are sensitive for feeling under boulders, picking up rocks and reaching into holes and cracks they are great tools for digging on the muddy bottoms of ponds and rivers, Extremely sensitive whiskers are used as sensors in the water to pick up the movements of potential prey. They are as comfortable hunting in crashing waves as they are in still ponds.
Females give birth to litters containing 2-5 young around early spring. Mating takes place in short periods throughout the rainy season in December. Afterwards, both male and females go their separate ways and return to a solitary life once more. Young are raised solely by the females reaching full maturity around one year of age.
Though mostly solitary animals, African clawless otters will live in neighbouring territories of family groups of up to 5 individuals. Each still having their own range within that territory, they mostly keep to themselves unless seeking a mate. Territories are marked using a pair of anal glands which secrete a particular scent. Each otter is very territorial over its particular range. If threatened, a high pitched scream is emitted to warn neighbouring otters and confuse a predator.
Keep a watchful eye and ear out for these charismatic animals.