Friday, May 30, 2014

Northern Bluet (Enallagma annexum)

Formerly known as Enallagma cyathigerum and its range believed to to be circumpolar, recent research indicates that the North American and Eurasian lines of this bluet diverged 250,000 years ago and the North American stock now goes by the epithet Enallagma annexum.

Northern and Boreal Bluets cannot be reliably distinguished in the field by sight and it's necessary to examine the male's terminal appendages or the females mesostigmal plates. A tandem pair of Northern/Boreal Bluets – both species have large postocular spots and tapering humeral (shoulder) stripes.

A dorsal view of a typical Northern/Boreal Bluet female – the paired blue spots on S8 may be fused in some individuals. The females can be either blue or tan.

The cerci of the male Northern Bluet are sharply upturned at their lower tips.

Terminal appendages of the Boreal Bluet – the cerci are rounded and angled downward.

The Vernal Bluet (Enallagma vernale) must also be examined in the hand to separate it from the Northern Bluet, the cerci of the male Vernal Bluet have a ridge. There's no way my camera will pick up that kind of detail but it should be visible with a 20× loupe, and thus far I have found no evidence of Vernal Bluets flying in my area.

As of this writing I'm uncertain whether the Vernal Bluet is considered a subspecies of the Northern Bluet (according to my field guide there is evidence of hybridization) or has been elevated to species level.

Thursday, May 29, 2014

The Return of the Juniper Hairstreaks

Last year in late May a friend photographed a Juniper Hairstreak roughly 1.5 km west of Tweed. We searched a nearby dry field that hosted scattered stands of Eastern Red Cedar and discovered a small colony of these elusive little butterflies.

It seems that Callophrys gryneus gryneus is still with us. This hairstreak is seldom encountered since south-central Hastings County is near the northern periphery of its range, and due to its relatively short flight season.

We sighted three butterflies and they looked freshly minted since they still had their little characteristic "tails" and strong colors. Presumably all of them were males because occasionally they would engage in what appeared to be territorial disputes that would go on for up to five minutes, one such contest involving all three butterflies.

I've often wondered ... what determines which individual wins these contests?

Wednesday, May 28, 2014

Ontario's Largest Natural Cavern

A little to the west of the intersection of Harmony Road and Shannonville Road in southern Hastings county lies the home of Ontario's largest natural cavern.

The story of Tyendinaga Cavern and Caves dates back to the Paleozoic Era during the Ordovician Period, when what is today's karst topography once formed the beds of ancient seas some 490 million to 440 million years ago. Fossil remains of the sea life can be found in the rocks surrounding the caves, and visitors are treated to mural painted by Elizabeth Koch and Ildiko Olive depicting their interpretation of the living animals. It's a shame there were background reflections and glare because the photograph really doesn't do the painting justice.

A mounted display of the smaller fossils and cave formations.

Much as they do today, sponges and corals thrived in the warm, shallow seas of this epoch.

A sponge shares this piece of limestone with a few smaller nautiloid shells. The Ordovician was the heyday of the Cephalopods and the remains of nautiloids and ammonites – distant cousins our modern octopuses and squids – abound in the limestone, attesting to their former numbers and diversity.

These ammonite shells are about 50 cm in diameter.

The mold or impression of a much larger nautiloid shell. The cast in the next image is a good healthy meter long.

Calcium carbonate has crystallized as calcite inside this nautiloid fossil.

Some aptly named honeycomb coral.

The fossilized "stem" of a Crinoid. Also know by the misleading name of Sea Lily, these were (and still are, although relatively uncommon) actually sessile animals belonging to the phylum Echinodermata, related to starfish, sea urchins and sand dollars.

And this fossil is a mystery ... could it possibly be the remains of some primitive vertebrate?

Elizabeth explains the formation of flowstone before we move on to tour the caves and their associated topography.

The caves are estimated to be about a hundred thousand years old – a mere geological blink of an eye – and the periods of glaciation (there were more than one) during this time were a force of both creation and destruction. Vast amounts of meltwater from the retreating ice would carve its way through the soft limestone forming caverns, only for them to by crushed by the weight of another advance of the ice and forming rubble filled sinkholes.

The Water Cave – the water level can rise rapidly during heavy rainfall.

The Hourglass Cave, so called because of its shape; a symbol of time is apropos considering the lengthy spans involved in the formation of the caves.

And here we are at the main attraction, on the other side of the doors are about a hundred meters of underground passages to explore.

Look up, waaaayyy up ... and I did, searching for – but not finding any – cliff-loving ferns with a preference for a basic substrate, such as Cliffbrakes or Wall Rues.

The caves are constantly changing and evolving, with mineral rich water continously seeping in and depositing calcium carbonate and creating formations called, appropriately enough, flowstone.

A rather eerie looking accumulation of flowstone.

Calcium carbonate left behind by water dripping from the cave ceiling forms the feature most people associate with caves – stalactites. Some of these are straw stalactites, so called because they are hollow. The bright spots at their tips are reflections of the camera's flash reflected from drops of water. We were invited to return in another thousand years or so, by which time the stalactites would attain a length of six or eight inches ... I can hardly wait ...

Water takes the shortest path, which isn't necessarily a vertical one, forming these fascinating deposits called cave curtains.

The pair of accretions to the left in this picture resemble a pair of dentures.

I neglected to ask (or have forgotten) what process shaped these intriguing little cave mushrooms. The "buttons" on their ends are wider than their "stems", and they can occur on walls that aren't vertical.

This passage is open to the public, but it's for advanced spelunkers only. No worries if you lose your grip on the walls whilst negotiating this crevice, you'll be wedged in tightly long before you hit the bottom an estimated 17 meters to 25 meters below.

Another tight squeeze, but somewhat more comfortable – on a mental level if not physically – to squeeze through knowing one's feet were on terra firma.

Calcium carbonate deposited by water seeping through the tiniest cracks and crevices continues to seal the cave with the passage of time. At this point the ceiling is more than seven meters above our heads and we're nearly twelve meters below the surface.

Ever wonder why our planet is sometimes called "Mother Earth"?

The walls bear dates left by passersby who stopped for shelter, or perhaps evading the long arm of the law, there's one inscription dated 1812. But no one left other than their initials at most, including the artist who created this cute little sketch. Could this be a "selfie", so to speak? There are still unknown and unexplored passageways down there in the nethermost bowels of the earth ... is it possible the caves are inhabited by a colony of Kobolds?

In addition to any hypothetical "little people", Tyendinaga Cavern and Caves is home to the Big Brown Bat, the Little Brown Bat and the Eastern Pipistrelle – and an arachnid affectionately nick-named "Charlotte".

Looking at her from a distance I mistakenly thought Charlotte might be a Charlie, because it seemed that she had the enlarged palps characteristic of male spiders (some photos of a male Meta ovalis). But zooming in on the photos on the computer established that the palps were actually her lunch and the spider is indeed a female. But now I wonder exactly what small denizen of the caves she is eating?

Despite the temperatures (supposedly 10° C give or take, but it sure felt cooler than that) a tiny worm was crawling up the cave wall. Will it get encrusted in the calcium carbonate and be fossilized, to be found by future alien paleontologists millions of years from now? Only time will tell, but since we're talking about time as measured in terms of geology where change often happens at a worm's pace ... we'll never know ...

Thursday, May 15, 2014

Salticid Snapshots

Saltation – from Latin, saltus, meaning "leap", and since jumping spiders lack extensor muscles at their leg joints they accomplish their amazing leaps by suddenly increasing the blood pressure to their fourth pair of legs. The precision of their predatory pounces is guided by their large AME – Anterior Median Eyes – the acuity of which are ten times better than the huge compound eyes of a dragonfly.

This pretty little female spider goes by the name of Marpissa formosa. She was found on the doorframe of a car and had probably been hitchhiking there for the past hour, hanging on for dear life. The reflective paint made a poor background, as did some red granite, but she obligingly jumped up and posed on my hand.

Male spiders are often much smaller than females; that's not the case here, both sexes were about 10 mm give or take. But they certainly are colored and patterned differently, and without a field guide or seeing a mating pair of spiders one would never guess that the male Marpissa formosa in the next two pictures is the same species as the female above.

Phidippus princeps (from Latin, meaning "first, chief, sovereign") is also roughly 10 mm long but much more robust. The salticid habit of always turning to face danger with those AME makes it difficult to acquire shots from different angles. In this case it presents this male's field marks quite nicely – white scaling on the palps, white fringes on the legs and blue-green chelicerae. The abdomen can vary between individuals and instars and isn't reliable for identifying this spider.

Like its cousin Phidippus audax a.k.a. the Bold Jumper this spider was totally fearless. He leaped at the camera, jumped on my hand (but of course didn't bite), and his last leap took him ... in my shoe? inside the leg of my pants? or he missed me and went into hiding? ... I'm not sure which.

A couple of Phidippus princeps females – again, there's not much difference in size between the sexes, but even so the females tend to be more robust than males. A good rule of thumb for sexing arthropods in general is "Eggs are bigger than sperm." In addition the males carry their sperm packets in specially modified pedipalps, the profile of which is unique to each species. The palps of females are unmodified, bristly and resemble short legs.

Phidippus princeps is as big as our local jumping spiders get, but the Regal Jumper (Phidippus regius) can attain a length of about 20 mm – large enough to tackle more than the standard menu of insects and other arthropods.

At the other extreme in terms of size is the diminutive Peppered Jumper (Pelegrina galathea). Attaining a length of only about 3 mm this mating pair of spiders was at the limit of the camera's macro.

The pair separated amicably after mating. The female fled the scene immediately but the male hung around for a minute and I was able to get a few photos for future reference.

A male Eris militaris a.k.a. Bronze Lake Jumper looks superficially similar to male Peppered Jumper, but it lacks the strong annulations on the legs, the branched white markings on the cephalothorax and the spots near the tip of the abdomen. In addition the Bronze Lake Jumper is about twice the length of the Peppered Jumper.

The vision of this small arthropod is amazing in proportion to its size. The male recognized a female of his species from a good 30 cm away and started signaling to her by wagging his abdomen and waving his modified front legs, making her aware of his intentions from a relatively safe distance. A necessary prelude to mating, because with their hair-trigger killer instincts jumping spiders will tackle anything that moves and looks small enough to overpower and eat.

The female is a few millimeters longer than the male and much heftier. She did have dinner on her mind, albeit a midge rather than her prospective mate, wasn't receptive to his advances, and no mating took place. So although the markings are correct for an Eris militaris female there are other jumper look-alikes and it's not possible to conclusively say these two spiders were the same species.

The attractive spider in the next group of photos is a female Dimorphic Jumper (Maevia inclemens), she's about 8 mm long.

This looked like a dramatic opportunity to acquire a dramatic shot of the spider catching dinner but it turned out to be something better. The spider homed in on the ant and started to leap but then aborted it, and when I looked at the image on the computer screen I saw why. It looks like the ant was threatening to (or maybe did) spray formic acid or some other nsty chemical at the spider.

Male Dimorphic Jumpers are two to three millimeters smaller than the females. Its small size combined with cryptic markings made this one almost impossible to see against the background of lichen encrusted stone. The males come in two color forms, here's an image of the other variation at BugGuide.Net.

Always look twice – I jumped to the conclusion that these itsy-bisty mottled brown spiders, only about 3 mm in length, were the immature instars of a species I was already familiar with, perhaps Salticus scenicus.

Not so ... one of the spiders became agitated at my presence and waved its palps around, whereupon it became obvious that this was a fully mature male.

Sometimes immigrant species die out because conditions simply aren't right for them in their new habitat. They may – like the ubiquitous primate Homo sapiens – find themselves in an favorable environment with a plentitude of food and lacking the limiting factor of predation, overpopulate their habitat and outcompete the native species, in which case they get bad press and have epithets like "invasive" hurled at them. Or, like the Asian Jumping Spider (Sitticus fasciger), they can blend into the background, fit right in, and live their little lives, doing what spiders do best ...

"If it is not small enough to eat nor large enough to eat you, and doesn't put up a squawk about it, mate with it." ~ (David L. Jameson, Systematic Zoology, 1955) ... that pretty much sums up the lifestyle of jumping spiders, and the rest of nature as well.