Archive for the ‘Golden Orb Spider’ Tag

Shining a Golden Light on Serpent Eyes   6 comments


Philip Davison. Costa Rica. Blog. Nature Diaries

Ray of Light

This July was probably the wettest that I have experienced in 16 years of living on the Osa Peninsula.  Here at Cabo Matapalo the total rainfall for the month was 38 inches.  But a lot of the rain came in heavy torrential downpours.  We did see a great deal of sun between the downpours.  Also much of the rain fell overnight.  One morning following a night long deluge the sun rose but while still low in the sky it cast rays of light through the tree trunks.  The shafts of light were emphasized by the rapid rising misty droplets creating a heated steam.

Osa Peninsula. Costa Rica.

The early morning sun breaks through.

Close Encounters of the Bird-eating Kind.

Snakes are notoriously hard to find in a tropical rain forest.  There are snakes on the ground and snakes in the trees, there are snakes out at night and there are snakes out during the day but locating snakes can be a thankless task at best and fruitless preoccupation at worst.  Sometimes snake hunters come to the lodge armed to the teeth with knee length leather boots, grab sticks and snake hooks wanting to engage in 24 hours snake hunting trips.  I have to lower their expectations by telling them that they can turn over every log and rock in the forest and they won’t find snakes.  Conversely people come and walk with trepidation on the forest trails in a state of dread in case they happen upon a snake.  Invariably these will be the people who will find them.

Last week while out on the butterfly transect I was walking through a section of forest, handheld recorder in one hand, camera in the other when I noticed a fairly large snake on the forest floor just to the side of the trail.  I stepped off the path to a position in front of the snake which had frozen and was watching me as I sunk slowly to my knees while lifting the camera to my eye.

As well as being hard to find snakes are difficult to photograph due to the linear dimensions of the body.  Unless they are coiled then only the head will be in focus while the rest of the body is either out of shot or too long for the depth of field to accommodate.  As I leaned forward to get my belly on the ground the snake lifted its head and the performance began.

The snake I was looking at was a Tropical Bird-eating Snake, (Pseustes poecilinotus).  It is also known as the Hissing or Puffing Snake as it has a tendency to turn its head sideways while flattening its neck laterally to give the impression of being larger than it actually is.  It whatever it is that is upsetting the snake, in this case me, it will strike out.  I managed to stay out of range as I did not want to risk a bite to the face.  This species is non-venomous but a snake bite in the vicinity of the eyes may not be such a pleasant experience.  However I did manage to get several shots before rising to my feet and continuing on my way while letting the snake go about its business once more.

Pseustes poecilinotus

Tropical Bird-eating Snake, (Pseustes poecilinotus)

Tropical Bird-eating Snakes are one of the larger serpents to be found in this area.  Fully grown they can reach up to 6 feet in length.  The ground color of the body is a pale blue/grey fused with orangey-brown patches.  The lips and lower sides are a brighter orange and quite often with a yellow belly and dark top to the head. As the name suggests their principal prey item are birds, more particularly chicks and eggs taken from nests.  Rodents make up some of the diet and I have seen them eat bats too.

Tropical Bird-eating Snake

Tropical Bird-eating Snake in Threat Pose

Remember if you visit the area it is highly unlikely that you will see a snake and the ones that you may stumble across will probably be non-venomous.  The snakes want as little interaction with you as you will of them and they will make themselves very scarce in short time so it is not something that should detract from the enjoyment of walking the trails.

Pecked Out Eyes

One of the comments that I come across is the eye spots on an Owl Butterfly when the wings are open resemble the eyes of an owl, (or any other large potential predator), and scare off whatever is trying to catch the butterfly.  As I have said previously in this blog it sounds like a good anti predator strategy but fails when put into practice as when the butterfly opens it wings, the spots which are on the ventral surface are then underneath and can’t be seen.

Morpho helenor

Damaged Blue Morpho, (Morpho helenor)

Many predators when aiming to catch, subdue and kill their prey will direct an attack in the area of the eyes because lying behind the eyes is the major part of the central nervous system, the brain.  Destroy the prey’s brain and the battle is over.  So many butterflies have a ruse that will use this attack to their advantage, they create a false eye.  It is usually large and distinct and placed at the trailing edge of the hind wing.  Any bird or lizard taking a peck or bite at the “eye” area will only be rewarded with a tatty piece of wing membrane while the main body of the butterfly makes its escape.

Caligo eurilochus

Damaged Owl Butterfly, (Caligo eurilochus)

With these two butterflies this damage can be seen quite nicely illustrated.  The Blue Morpho, (Morpho helenor), has a line of eye spots down the trailing edge of the upper and lower wing.  As can be seen the wing has already been pecked at and torn in that area yet the butterfly is still capable of flight.  With the Owl Butterfly, (Caligo eurilochus), very obviously the attack was directed against the “eye”.  More often than not, unless it is newly emerged, the Owl Butterflies will be missing this part of the wing when seen in the wild.  It buys the butterfly a second change to locate a mate to partner with and reproduce.

Big-legged Bug

It is thought that the term bug comes from the Old English word for a goblin.  The tern bug when applied zoologically refers specifically to the order: Hemiptera.  This order is divided into two sub orders depending upon the structure of the wings.  The sub order: Heteroptera have the wings divided almost equally into a thick basal part and a thin distal part.  The sub order: Homoptera have the wings completely thin and cellophane-like.

As you can see this Big-legged Bug, (Pachylis tenuicornis), is a heteropteran with wings being clearly divided into two textures. It belongs to the family: Coreidae, the Big-legged or Flag-legged Bugs.  The hind legs are very swollen and stout.  This individual flew past me in an area of grassland where it landed not too far away on the ground.  The thing that caught my eye was the bright red coloration of the body beneath the wings.

Big-legged Bug

Big-legged Bug, (Pachylis tenuicornis)

The Big-legged Bugs when attacked by a predator lift the wings to reveal that bright coloration which warns of an impending defensive measure, notably that it is about to spray from glands an offensively odorous fluid.  The fluid discharges from a gland on the thorax and opens by way of a pore on either side.  The gland has a valve which allows one or the other or both pores to discharge at once.  The cuticle around the pores is sculpted so that when the fluid is sprayed some of it remains on the body providing even further protection.  Thankfully I did not disturb this individual so much as to stimulate such a reaction.

How to Spin a Golden Orb

One of the commonly seen spiders in this area, due to their large size and elaborate webs, is the Golden-orb Spider, (Nephila clavipes).  Its large size and striking black and yellow coloration along with the “furry” legs make it look very dangerous but it is in fact totally harmless to humans.

Nephila clavipes

Female Golden-orb Spider, (Nephila clavipes)

Like just about all other spiders they are carnivores using both traps and venom to catch and immobilize the prey.  The trap is the web or orb.  In the case of the Golden-orb Spider it is made from a yellow silk which gives the spider its name.  Outside the forest the web is made from a deeper yellow silk which attracts bees so a large percentage of its diet in more open areas is bees.  Inside the forest it is made from a much paler silk.

Normally with orb weavers when something lands in the web they rush towards it and envelope it in sheets of silk to completely immobilize it before injecting the venom. The Golden-orb Spiders on the other hand bite first and then wrap in silk.  If the victim caught in the web is a large or aggressive ant or wasp she won’t take it on because there is a good chance she will be stung o bitten before she can get her bite in.

Webs are fascinating structures.  Although not so obvious to the human eye each spider has a web that is structurally pertinent to the species.  That means there are as many different types of webs as the number of species that create them.  As most people are aware the web is made from silken strands that are meticulously meshed together to produce one of nature’s most amazing death traps.

Silk is not exclusive to spiders, some other invertebrates are capable of producing silk, it is just that spiders are the unreserved masters in the production and utilization of silk and all spiders are capable of producing silk.  Silk itself is a remarkable substance.  It is a proteinaceous material stored as a liquid in the spinning glands.  When spun by the spider it turns from a water soluble liquid to an insoluble silken thread and this change occurs due to tension orienting the molecules rather than exposure to air.  The nature of the thread means it has both strength and elasticity. Spiders can produce many types of silk depending upon the use to which it will be put.  In a web there may be dry silk which is stiff and used as the framework while a moist viscous silk capable of stretching 300% of its original length is used as the sticky catch net.

Golden-orb Spider

Golden-orb Spider, (Nephila clavipes) producing silk

The spider has 3 pairs of independently mobile spinnerets on its abdomen.  Each spinneret ends in a spigot through which the silk gland exudes the silk.  As the proteinaceous silken thread is produced other cells in the silk glands secrete mucopolysaccharides which give it a viscous coating.  The mucous coating takes water from the atmosphere which separate into small droplets along the length of the fiber which in turn gives it the highly elastic quality to take the momentum from a large insect hitting the web as well as the glue-like adhesiveness which then holds it there.

Nephila clavipes spinnerets

Golden-orb Spider close up of spinnerets

I used extension tubes with a 105mm macro lens to try and capture a close up of the spinnerets of this Golden-orb Spider.  The spider is fairly large which made the task a little easier.  You can see the silken line being produced as well as the mucous globules along its length.

Philip Davison is a Biologist, Writer and Photographer Based in Costa Rica.

Cat Scratch Fever   Leave a comment


Felipe del Bosque Blog August 17th 2013

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Interrupted Halcion Days

This week has followed more or less the same pattern as last week with the area experiencing warm, dry and bright days with a small amount of rain falling over night.  It is just enough to keep  the area damp with a humid atmosphere.  Towards the end of the week more and more began to fall until eventually the days turned grey and the rain persisted for more or less 24 hour periods.  Then just as we thought we might have seen the last of the sun until November, out it came once more.

That is the problem with predicting the weather here.  The national forecast can give you the weather for a wide area but locally the difference between conditions at Bosque del Cabo and only a few miles in either direction can be that of a hot bright sunny day versus an overcast chilly deluge.

Jackpot

Changing the memory cards in the cameras on the Titi Trail is always a prelude to excited anticipation.  Every Saturday the cards are removed, brought back to the lodge, inserted into the laptop and then meticulously scrutinized for whatever was taking place on the trail over the last seven days.  Any humans are immediately eliminated.  Dates and times are recorded for each species so we can build up a data base of activity.

After six weeks we know we are going to get a lot of the same animals stealing the majority of the show.  Camera #1 is place in an area where there is more dense growth around and above the camera.  Here we get a lot of videos featuring Agoutis,(Dasyprocta agouti), during the day and their cousins the Pacas, (Agouti paca), at night.  This is also the area where we find Tamanduas, (Tamandua mexicana), Nine-banded Armadillos, (Dasypus novemcinctus), Common Opossums, (Didelphis marsupialis), Red-tailed Squirrels, (Sciurus granatensis), as well as some Collared Peccaries, (Tayassu tajacu) and the occasional White-lipped Peccary, (Tayassu pecari).

M2E34L105-105R398B310          M2E1L0-0R350B300         M2E35L109-108R398B307

Red-tailed Squirrel         Paca         Collared Peccary

Camera #2 is much closer to the end of the trail. The path is much clearer and the trees above are more open crowned so it tends to be a lot lighter.  Once again we have Agoutis active during the day and Pacas at night.  But this area really does seem to be alive with White-collared Peccaries 24/7.  Peccaries of all ages, in large or small groups or even alone walk every which way on this trail.  If our guest walk this trail they can see for themselves the ground criss-crossed with hoof prints.  However this last week some of our guests saw prints that were not only distinct but huge too.  A big cat had walked this way.  He had left his mark in terms of pugmarks around various parts of the property.

So the memory cards were duly brought back and the video viewing began.  Each video is of 30 seconds duration and if when it commences you can see any of the above animals you can move on.  Sometimes the camera will have been triggered by movement of something not in shot.  If after the time is up and nothing has been seen then the video is deleted.  This week there were 600 videos to sit through.  Another Agouti, another peccary, some more visitors, all very nice but where is the special guest star?

Camera #1 had 300 videos, there was a great deal of animal life but no cat.  Camera #2 had another 300 videos to sift through.  Up to  #272 there were endless videos of some Agoutis but mostly peccaries, a great many of which were of excellent quality. Then came video #273 and BINGO, we hit the jackpot.  A fabulous video of that huge male Puma, (Puma concolor).

M2E40L148-147R412B318

You can see he looking for something.  The resident Bosque female, “Half Tail” is commonly found on that trail.  But he is also in “Peccary Alley” and there is nothing Pumas like to eat more than  tasty little peccaries.  The Spider Monkeys in the trees above are fully aware of his presence, they are giving the incessant and frantic high pitched bark that constitutes the alarm call reserved for large cats.  If ever you hear that sound coming from somewhere in the forest then you know full well what is walking on the forest floor.

The fun did not stop there.  The handsome predator goes walking past camera but the next photo shows him in full flight running back from whence he came.  The chance of snatching a single peccary that may have strayed too far from the herd might be worth the risk of a feline hunter of this size venturing into “Peccary Alley” but it is however a risk.  There are sizeable numbers of peccaries in this area.  They are not going to tolerant of something posing a threat to them or their offspring.  A defensively agitated peccary would be a fearsome adversary at the best of times but multiply that number into 10 or 20 plus and you have a potential life threatening situation on your hands, (paws).

The photo was that of the rear end of the Puma fleeing for its life.  The next video showed why.  Irate peccaries numbering in groups of 3 or 4, one group after another, all charging along the trail, the hair on their bodies bristling, the scent gland exposed, grunting and huffing, but more particular the clacking of the teeth.  The action was fast and furious.  The Puma had no chance, it was so outnumbered.  Once the excitement had died down and the peccaries were satisfied the predator had been shown the true order of world they returned to “Peccary Alley”.  The next few videos show the self-congratulatory individuals of the repulsive warrior force rubbing against one another sharing in an exchange of glandular secretion to bond the herd.

Slow to Show

One group of creatures very noticeable by their absence in these tropical forests are the mollusks. It has  been suggested that the soils in the area have low levels of calcium and therefore lacking in shell building material.  There are no shortage of marine mollusks but then there is no shortage of calcium in the sea.  The land crabs are crustaceans and so have an exoskeleton composed of calcified chitin, a protein, the calcium initially coming from the crabs formative time in the ocean and the subsequent visits to the ocean on the annual reproductive migration.  Many of the snails to be found in these forests are carnivorous, (feeding on other snails), but tend to be small with translucent thin shells.

Tropical Land Snail

This particular mollusk had a very thick large shell.  On thirteen years of walking through the forests of Bosque del Cabo I very rarely see mollusk and this particular species I have only seen live on 2 or 3 occasions. Identifying the species has proved somewhat difficult by I will keep searching.

Black and Yellow Peril

Scattered throughout the gardens of Bosque are several specimens of a plant native to Central America but more familiar to those guests who have visited Hawaii where it is not in fact native and that in fact is Frangipani, (Plumeria rubra).

This week it was noticed that the Frangipani was host to a plague of very large caterpillars munching their way through the leaves.  The caterpillars were so distinct, not only due to their large size, but also the eye-catching velvety black and yellow banding and the vivid red heads.  They were without doubt moth caterpillars whose identities are not always easy to arrive at given the number of species. These ones posed no such problem though, they are the larval stage of the aptly named Frangipani Moth, (Pseudosphinx triota).

Frangipani Sphynx Moth

The caterpillars are so spectacularly large and so brightly colored it would seen as if they were just a meal waiting to be consumed by any bird or lizard.  They also have the habit of lifting the front end of the body and waving the head violently from side to side which is not the  exactly behavior of an animal trying to remain hidden from view.  In point of fact black and yellow is the most visible color combination that exists and animals bearing this most acutely bicolored attire want you to be aware of and shun their presence.  Think of it, bees, wasps, hornets all sport these colors as do many poisonous butterflies, spiders and snakes as well as some species of poison dart frog.  This is aposomatic coloration otherwise known as warning coloration.

Psuedosphynx triota

The caterpillars of The Frangipani Moth before consuming the Plumeria leaves bite through the base of the leaf stalk.  A white milky latex leaks out thereby stemming the flow into the leaf.  But  some of the latex the caterpillar imbibes.  It contains alkaloids which then render the caterpillar distasteful, and cyanogenic glycocides, (cyanide), which render it downright poisonous, to any unsuspecting and naive predator.  Better take notice of that warning coloration.

Banana vs Small-heads

Over the past few blogs I have posted information and photos separately of two small yellow frogs found by the pond this time of year.  Below I have posted two photographs to show the two species in juxtaposition.  The top photo is the Banana Frog, (Dendropsophus ebreccatus), and the bottom photo is the Small-headed Frog, (Dendropsophus microcephalus).  These two individuals were photographed on the same evening very close to each other.  The Banana Frog is handsomely marked with large blotches of yellow and tan.  The Small-headed Frog is more uniformly colored with stripes down the length of the body.  However the two species are not always so distinctly marked which causes the confusion in identity.

Banana Frog

Small-headed Frog

Philip is a biologist, writer and photographer as well as the onsite naturalist guide at Bosque del Cabo Rainforest lodge on the Osa Peninsula, Costa Rica.

www.bosquedelcabo.com

Photo Feature

Legging It

The past few weeks have been good for spiders which may or may not be good news depending how you feel about these creatures.  Arachnids in general seem to have a polarizing effect on peoples behavior.  In these forests there are a great many spider species and they are not that easy to identify sometimes. There are 2 commonly seen species of bark scorpion and a night it doesn’t take much searching before you will find tailless whip scorpions.

I always find that spiders make a good subject for photography as they are generally stationary, either on the vegetation like the wandering spiders, disguised amongst the flower heads such as the crab spiders or suspended in a web such as the orb spiders.  Macro photography and orb spiders pose a little bit of a problem as the spider is not compact, having eight spread legs and any slight zephyr of wind will move the web in an out of focus including, of course, the spider itself.

I you choose to look it won’t take too long before you start to notice that Bosque is not short of spiders of any sort.  The Golden Orb Spiders, (Nephila clavipes), are perhaps the most noticeable as they make very large webs of bright yellow silk and in areas very close to or in the restaurant and around the cabins.  The spider itself is impressively large.

Golden-orb Spider

You will notice the large and seemingly complex web is made from two types of silk.  The orb is made from a sticky silk.  Outside the forest the silk is much brighter yellow in color.  This attracts in bees so 60% of her diet outside of the forest is bee.  Inside the forest the web is made from a much paler silk which largely remains invisible to a lot of insects.  The orb is being held in place by a non sticky silk which has a tensile quality half that of the finest steel.

Normally with orb spiders when something lands in the web they approach it, wrap it in silk and then deliver the lethal bite.  With the Golden Orb Spiders she approaches the stuck prey, bites first then wraps in silk.  So if she gets something such as a large aggressive ant or wasp trapped in the web she will not take it on in fear of being stung or bitten before she can deliver her kiss of death.

Close inspection may reveal other spiders living in her web.  The female sits in the centre and normally sitting in attendance above her is a small brown spider which is the male.  The male remains small but the female grows huge.  At the periphery of the orb there are tiny little spiders living a precarious existence.  These are kleptoparasites and they live by stealing her silken wrapped food parcels of predigesting prey left dangling from various locations in the web.  The female will tolerate kleptoparasites to a certain degree, they are adapted to living in her web and avoiding her, but once they become too numerous she will depart and build a new web elsewhere.

The female Golden Orb Spider can grow very large and may appear to be very intimidating but in fact she is totally harmless.  If you should be walking the trails and didn’t see the web, go crashing through it and end up with the spider climbing up your arm, it will not harm you, all you need do is pick it up and place it back on a leaf.

Another commonly seen spider that superficially resembles the Golden Orb Spider is the Silver Orb Spider, (Argiope argentatum).  The web is not as complex and is made of the more typical white colored silk familiar to most people.  They are reasonably large spiders and quite often have a telltale feature to the webs in the form of a large white cross.  This is known as a stabilimentum and can be visible for some distance from the web.

Silver-orb Spider

Much smaller in size and quite pretty as far as spiders go is the Orchid Spider, (Leucauge venusta).  They are Long-jawed Orb Weavers, Family: Tetragnathidae, but the spider is tiny and consequently the webs tend to small to, inserted as they are between the leaves of one plant as opposed to the two species above which can have their webs extended between two different plants.  Orchid spiders typically construct two types of web, the more commonly seen orb and another web which is produced as sheets of horizontally placed silken lines.  It was in just such a horizontal web that this Orchid Spider was photographed.

Orchard Spider

Studies of the Orchard Spider has shown that as the females mature they build their web in vertically higher strata of the vegetation.  The lower webs catch more insects but smaller in size than the higher webs which capture fewer insects but larger in size.

Although it spins a network of silk, the Lynx Spider, Family: Oxyopidae, are active daytime hunters.  They have excellent eyesight and use vision as the means by which to detect prey upon which the jump and dispatch before consuming.  This one was found in the Tropical Garden finishing sucking the juices out of its victim, one of the bee species. The opisthosoma, (body), is quite elongated and the legs are long and held in a basket-like grasping fashion.

Lynx Spider

Just walk around the grounds, keep your eyes open and re-adjust your point of focus and a whole different world, an amazing small world, will be revealed.

Text and Photographs are taken from the forthcoming book:

The Natural History of Bosque del Cabo by Philip Davison

Temperature and Rainfall

Average Daily Rainfall 0.69 ins.  Total Weekly Rainfall 4.82 ins

Average Daily Rainfall 17.5 mm.  Total Weekly Rainfall 122.4 mm

Highest Daily Temp 87°F.  Lowest Daily Temp 74°F.

Highest Daily Temp 30.8°C.  Lowest Daily Temp 23.5°C.

Species List for the Week

Mammals

  • Mantled Howler Monkey
  • Spider Monkey
  • Squirrel Monkey
  • White-faced Capuchin Monkey
  • Nine-banded Armadillo
  • Tamandua
  • Common Tent-making Bat
  • Western Red Bat
  • Common Opossum
  • Kinkajou
  • White-nosed Coati
  • Agouti
  • Paca
  • Alfaro’s Pygmy Squirrel
  • Red-tailed Squirrel
  • Underwood’s Pocket Gopher
  • Collared Peccary
  • White-lipped Peccary

Birds

  • Mealy Amazon
  • Orange-chinned Parakeets
  • Red-lored Amazon
  • Scarlet Macaw
  • Gray-necked WoodRail
  • Great Curassow
  • Crested Caracara
  • Rufus Piha
  • Black-hooded Antshrike
  • Chestnut-backed Antbird
  • Short-billed Pigeon
  • Red-Capped Manakin
  • Chestnut-mandibled Toucan
  • Grey-headed Tanager
  • Bright-rumped Atilla
  • Golden-crowned Spadebill
  • Great Kiskadee
  • Great Tinamou
  • Black-throated Trogon
  • Black Vulture
  • Turkey Vulture

Reptiles

  • Barred Ameiva
  • Cat-eyed Snake
  • Central American Coral Snake
  • Central American Smooth Gecko
  • Common Anolis
  • Common Basilisk
  • Clawless Gecko
  • Four-lined Ameiva
  • Golfo Dulce Anolis
  • Litter Snake
  • Mediterranean House Gecko
  • Pug-nosed Anole
  • Salmon-bellied Racer
  • Terciopelo
  • Tropical Bird-eating Snake

Amphibians

  • Banana Frog
  • Black and Green Poison Arrow Frog
  • Golfo Dulce Poison Arrow Frog
  • Fitzinger’s Rain Frog
  • Masked Smilisca
  • Marine Toad
  • Milky Frog
  • Parachuting Red-eyed Green Tree Frog
  • Red-eyed Green Tree Frog
  • Rough-skinned Dirt Frog
  • Savage’s Thin-fingered Frog
  • Small-headed Frog

Butterflies

  • Anartia Fatima
  • Anartia jatrophae
  • Colobura dirce
  • Consul fabius
  • Dryas iulia
  • Eueides aliphera
  • Eueides lybia
  • Glutophrissa drusilla
  • Heliconius erato
  • Heliconius hecale
  • Heliconius ismenius
  • Heliconius sapho
  • Hermeuptychia hermes
  • Mesosemia zonalis
  • Morpho cypris
  • Morpho helenor
  • Morpho menelaus
  • Phoebis sennae
  • Pyrgus oileus
  • Siproeta stelenes

Plants

  • Alamandra  cathartica Flowering
  • Alpinia purpurata Flowering
  • Apeiba tibourbou Flowring
  • Arachis pintoi Flowering
  • Arundina graminifolia Flowering
  • Attalea rostrata Fruiting
  • Bauhinia variegata Flowering
  • Cascabella thevetia Flowering and Fruiting
  • Citrus spp  Fruiting
  • Clusia rosea Flowering
  • Clusia vallerii Fruiting
  • Cocos nucifera Flowering and Fruiting
  • Crestentia alata flowering and Fruiting
  • Costus speciosus Flowering
  • Dypsis lutescens Flowering and Fruiting
  • Etlingera elatior Flowering
  • Ficus citrifolia Fruiting
  • Ficus insipida Fruiting
  • Heliconia chartacea Flowering
  • Heliconia latispatha Flowering
  • Heliconia pogonantha Flowering
  • Heliconia psittacorum Flowering
  • Heliconia rostrata Flowering
  • Hibiscus rosa-sinensis Flowering
  • Hymenaea coubaril Fruiting
  • Hymenocallis littoralis Flowering
  • Ixora coccinea Flowering
  • Lantana camara Flowering and Flowering
  • Morinda citrifolia Fruiting
  • Musa acuminate Flowering and Fruiting
  • Nephelium lappaceum Fruiting
  • Pachira quinata Flowering
  • Piper auritum Flowering and Fruiting
  • Piper nigrum Fruiting
  • Piper umbellatum Flowering and Fruiting
  • Pleiostachya pruinosa Flowering
  • Plumeria rubra Flowering
  • Stachytarpheta frantzii Flowering
  • Zammia sp Flowering

 

 

SPIDERS – SLOWLY WRAPPING IN GOSSAMER THREADS   1 comment


The day started with rain, actually it continued raining from last night and it rained all day .  It is not the heavy torrential rain that one associates with the usual early evening downpour, but rather that fine indistinct line between drizzle and mist with an intermittent heavier shower.  All of this makes for a very atmospheric feel to the forest and the grounds.  The trees are visible but appear almost phantom-like in a gloomy half light, obscured by mist.  It is as if you are looking at a picture with the color removed, a grayscale image.

The dim, murky conditions, however atmospheric for us, seem to dampen the enthusiasm of the animal life.  Mammals and birds are not easy to see in a rainforest under the most optimum of conditions.  Now add to that a heavy mist and you don’t have conditions conducive to a lot of sightings.

Anteaters – Dimly Engaging

Whatever the conditions, you never know what will turn up and this morning as I wound my way along the muddy trail through the dank forest, bumbling along at its own pace coming from the opposite direction towards me was a Tamandua, otherwise known as the Collared Anteater, (Tamandua mexicana).  Now, although they are not rare, it is also not that common to see a Tamandua.  Along with armadillos and sloths, the anteaters constitute the mammalian order: Xenathra.  One trait, apparently shared by all the Xenathra is an ostensible lack of awareness for their immediate environment.  I have stood still in the forest and had sibling quads of Nine-banded Armadillos running back and forward over my feet without any fear, I doubt if they even knew I was there.  In the past I have walked alongside a Tamandua, that has remained oblivious to my presence until I accidentally stepped on a dead twig, the snapping of which sent it unhurriedly up a tree, only for it to stop about 4 feet off the ground and lift its nose, smelling the air to see if I was still in the vicinity.  And so it was this morning, up it came, intently concerned with its own business, searching for a meal of termites, (despite being called anteaters, they prefer a diet of termites), walked straight past me and on to wherever it may have been going.  This was a repeat performance of last night, when I had a Nine-banded Armadillo trundling along in front of me and displaying a complete lack of awareness as to my proximity.  In evolutionary terms I sometimes wonder how they made it this far along the line.

Costa Rica. Rain Forest. Xenathra.

Northern Anteater, (Tamandua mexicana)

Spiders – Slowly Wrapping In Gossamer Threads

If you are having problems finding and photographing wildlife it then look for spiders.  They come in all sorts of shapes and sizes, some that we consider a typical spider and others more weird and bizarre in form.  Spiders are the eighth most numerically named group of animals on the planet.  There are 20 000 named species of spider in Costa Rica.  You should also be able to find them irrespective of the weather conditions.  Spiders in webs make a good subject, especially if a breeze is not blowing.  If there is the mere breath of wind it makes the task of focusing on a moving object close to the lens a little difficult, if not impossible.  Placed motionless in the center of a web is where an orb spider will normally sit unless disturbed.  That means, if you can avoid touching the web, you should be able to get pretty close.

Silver Orb-spider sitting in the middle of web woven with silken stabilimentum.

Silver Orb-weaver, (Argiope argentata)

Orb spiders are some of the more evolutionary advanced of the arachnids.  Spiders are posed with two big problems, how to catch prey and how to consume it.  Several groups of arthropods have evolved the use of silk.  People think primarily of butterflies and moths, the caterpillars of which will use silk to make cocoons, (silk comes from Silk Moth caterpillars), or hold the chrysalis to a leaf or twig.  But nothing has perfected the use of silk to the imaginative and creative extent of the spiders.

Silk – Beautiful But Used to Deadly Affect

Silk is a protein.  It can be constructed from two forms of amino acid, a very loopy amino acid which can make it very elastic, or a crystalline amino acid which can make it very rigid.  In the silk glands of the spider, silk is a liquid, once the spider creates a silken thread, it becomes a solid.  Once silk is a solid, it stays a solid, the process cannot be reversed.  Silk is very elastic; it can be stretched to 300 times its own length before it snaps.  It can have the tensile quality half that of the finest steel.  Finally, if you were to take a strand of silk and let it float on a breeze, it would drift 50 miles before it broke under its own weight.  So, all in all, an absolutely amazing and versatile material.

Orb spiders have the ability to spin up to eight different kinds of silk.  To construct a web, the orb spider first spins a rigid silk which will form the framework.  It then moves from the centre to the outside attaching radial lines to the vegetation.  Finally it returns to center and proceeds to spiral from the inside to the outside spinning a silk which when produced, absorbs water and becomes sticky.  The trap is now set.

Bright yellow Tropical Orb-spider sitting in the center of a silken web.

Tropical Orb-weaver, (Eriophora ravilla)

If the web was taut, an insect the size of a large beetle hitting it at high speed would just be bounced off.  The fact that the silk is elastic allows the web to give, thereby removing all the kinetic energy from the impact, it then recoils and the prey is caught in the sticky silk.   That forceful contact will cause vibrations; the spider twangs the radial lines to locate the prey’s whereabouts, quickly goes down, wraps the unfortunate victim in silk and then delivers the poisonous bite.  The venom is a neurotoxin which will quickly quell the struggling of the now silken wrapped meal.  The food parcel is placed in a part of the web where the prey will be digested within the confines of its own skin by digestive enzymes injected at the same time as the venom.  When the prey is ready to be eaten, the spider, sticks in the chelicerae and sucks out the liquid soup.

Rainforest animals. Spiders. Orb-weavers. Araneidae. Araneae. Eriophora sp.

Beetles final moments in the embrace of a Tropical Orb-weaver, (Eriophora sp)

There are some animals though, that have evolved the means by which to escape their seemingly inevitable doomed entrapment.  Butterflies and moths are Lepidoptera, which means “Scaled wings”.  If you look at the wings of butterfly, you will find it is covered in tiny little powdery scales.  If you handle a butterfly you will find the scales come off in contact with your fingers.  If a butterfly or moth lands in a spider web, the scales shed from the wings allowing it to slide down over the web surface and away to freedom.  That is, if the spider is not too quick to detect where they are in the web, otherwise they will share the same ultimate fate as any other insect unlucky enough to have flown into that silken trap.

Golden-orb Spider. Webs. Spider venom. Araneidae. Araneae. Nephila clavipes

Ventral view of a Golden Orb-weaver, (Nephila clavipes), sucking the juices from a butterfly victim

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