invertebrates – Page 31

Wings of a warm week

This past week we’ve had beautifully warm temperatures. Up to 20 C (68 F) or more on some afternoons, warm enough to wear a t-shirt (some warm-blooded types might also pull out the shorts or skirt, but I need for it to be at least 25 before I’d feel comfortable with bare legs. Either that, or sitting in the sun with no breeze). These warm daytime temperatures translated into warm nighttime temperatures – a regular occurrence come late May, but in April are worth taking advantage of for mothing. Some early-spring species live for these warm April evenings, and there are many that are more difficult to find as the season wears on.

As indicated last post, early this week I was at my parents’, out in the middle of the countryside. The rural setting there, it turned out, and the relatively diverse habitats on the property resulted in an excellent collection of species observed over the two nights. I ran the blacklight and sheet in the self-portrait of the first photo for a few hours of the evening, shutting down about midnight, and then had my trap set up which ran the whole night. In the pic it’s shown with a blacklight, but I actually had the more powerful mercury vapour bulb in it, which I think helped with the night’s catch. Although the blacklighted sheet didn’t do too poorly, either, really. It wasn’t a wide array of equipment; I also had two more blacklights and an extra sheet to what I put out, but I didn’t want to have to spend a lot of time taking it all down. And, as it turned out, I didn’t really need it anyway.

I ended up with a conservative estimate of 42 species, but there was probably a few more than that – I haven’t yet ID’d all the little small guys, and there’s a good chance that, with my inexperience, I may have written off some stuff as variations of other more common species. This isn’t too shabby for mid-April, as I understand it. Most of these species have emerged from overwintering as larvae or pupae, but a few overwinter as adults. They tend to be the raggedy ones, at least in the spring. Later on in the year the raggedy moths are just worn with age. As I photographed them I released them on to a concrete statue of a raccoon my mom has beside their front stoop. Because they go into a sort of torpid state they didn’t move very far after I placed them on the statue.

This was possibly my favourite moth from the two evenings. I caught five of them total, three on one night, and two the other (it’s possible that one or both of the two were among the three caught the next night, I suppose). It’s a Lettered Sphinx, one of the smaller of the sphinx moths, and fairly blandly coloured compared to many other sphinxes. I loved the way it curls its abdomen up when at rest. I didn’t realize what it was at first, something about photographs of sphinxes makes them look bigger than they really are. This was actually one of the larger moths I caught, but it was still less than 4cm (perhaps 1.5″) long. For whatever reason, these moths only came to the mercury vapour bulb at the trap, I didn’t have any at the sheet.

Another that only came to the trap was this Dogwood Thyatirid. Considering the abundance of Flowering Dogwood, the larvae’s host plant, at my parents’, it wasn’t a great surprise to discover five in the trap over the two nights, either. They’re a pretty nice moth, with a hint of pink to the whiteish patches that just doesn’t really come through in the photos well.

This moth was the opposite, I had five individuals over two nights that only ever came to the blacklighted sheet. Now why would that be? I hypothesize that the blacklight produces a slightly different wavelength of UV light that the different species orient to with greater or less preference. But really I don’t know. This striking green moth is The Joker, and was the very first moth on the very first night. Considering that up to that point most of the moths I’d seen were rather drab, this really made my evening. And, I gather, they only get better from here.

Here’s another one that I was pleased to see. It belongs to the genus Caloptilia, and it’s tiny, less than a centimeter long. This group of moths are among the leaf miners that create trails through deciduous leaves. Like the sphinx moths, when I first saw photos of these guys I thought they were substantially larger than they really are. I thought they were pretty neat-looking, propped up on stilts as they seemed to be. I got one to a sheet last fall, and immediately recognized it (it’s really a rather distinctive shape and posture), but was a little shocked at how tiny it was. Little moths (the so-called micromoths) are tricky to photograph because they tend to come out of torpor very quickly, basically as soon as you disturb them, because their small size means their bodies warm up and resume normal function very quickly. I got two of these guys, both in the trap. The first one I only got a photo of it on the carton it was resting on while in the trap; as soon as I nudged it to try to get it onto something more photogenic it took off. This one is waving its antennae furiously as it contemplates leaving.

This last moth I like because of the intricate mottling and nice mossy-green shading to the pattern. It’s a Grote’s Sallow, and I think I got five between the two nights (what is it about the number five?). Imagine this guy tucked into a crevice on an old, jagged-barked tree trunk. He’d blend right in and you’d never know he was there.

It’s hard to pick just a few species to highlight of the dozens I got, but those were definitely among my favourites. Those interested in checking out more of what I got can visit my moths series on Flickr.

I’ll wrap up with this photo of Lettered Sphinxes snickering behind a Curve-toothed Geometer’s back.

Monster bug

Yesterday I returned to my parents’ for a couple of days, and took advantage of the warm weather last night to try for some moths. There’s a great diversity of habitat here, with a mature mixed forest on one side, open scrubby areas to another, of course the wet swamp in the corner of the property. So I was hopeful for some good stuff, and I wasn’t disappointed. That all will be the subject of another post. I’ll be setting up again tonight (I head back home tomorrow), to hopefully add to the list.

I ran my new trap overnight, but I also put out a sheet and blacklight. I got a number of species at the blacklight that didn’t show up in the trap, and some nice ones among them. However, the most interesting thing to come to the sheet last night wasn’t a moth at all. Most of the time I just glance over the beetles and wasps and midges (I can only focus on one taxon at a time, and currently it’s the moths). But I couldn’t ignore this guy. I was leaning forward investigating some moth on the sheet when a very loud buzzing whirr whizzed by my head and flopped on the ground in front of the sheet. Out of the corner of my eye I thought it was a sphinx moth or something big like that, but when I stooped to investigate, it most definitely was not. My second impression was of a cockroach, since it had the same dorso-ventrally flattened body.

But it’s neither. In fact, this is a Giant Water Bug, also called Giant Electric Light Bug, after its habit of coming to artificial lights. It was rather alarming in its size and apparent ferocity. Fortunately, the same features made it very easy to identify. I got a clear plastic container and brought it inside to show my mom. She joked that she wasn’t going outside at night again.

It’s about 6cm (or 2.5″) in length, with these giant broad modified front legs that it uses to secure its food. As its name indicates, it’s an aquatic insect, primarily, associated with swamps and wetlands. Normally it lives in or near the water, preying on aquatic insects, but supplementing this diet with opportunistically-caught vertebrates such as frogs or small fish. It uses a tubular rostrum to suck out the body fluids of its victims. It can inflict a painful bite, and so also has the name “Giant Toebiter”, which I would assume dates back to the days when kids were more likely to wade into mucky water barefoot (I used to do that as a kid, carefree about the creatures inhabiting it; I’m more cautious now, but it’s more because of concerns over submerged or buried sharp things, especially glass or metal garbage).

Check out the giant eyes, which it obviously uses in stalking its prey. Plus the giant single claws at the end of each leg. I’m not sure what the white goop on its one eye is. The bugs are found across North America; there’s actually three species that are similar in appearance (I’m not sure which one I have here), and which overlap in range. Young look similar, but are obviously much smaller and take smaller prey. It takes them five moults to reach adulthood, which they do in a season; they overwinter buried in the mud as an adult. This site suggests that adults are edible, but I’m not sure I’d find them much of a delicacy.

When I copied the photos to my computer and looked at them closely, I discovered that the bug had been carrying what I took to be mites. You can also see a couple of large ones in the second photo, where it has its wings spread. I have no idea what species they are, or even if they are really mites, and not fleas or some other parasite like that. It seemed to have a good infestation going.

It’s amazing how it’s possible to overlook something that you would think would be quite obvious. If it comes to lights, why have we never seen it at the porch light? And being so large, you’d think we would have noticed it one of these times when down poking around the ponds. But it somehow escaped our notice to now.

Along came a spider

When I was down at TTPBRS on Thursday, it was a pretty quiet day. Not too many birds around, so I spent some time examining the walls of one of the buildings for bugs or other interesting things. One of the creatures I came across was this jumping spider. Jumping spiders are tiny, less than a centimetre long, and fairly stocky. This particular one is a Zebra Spider (Salticus scenicus), so called for the striping on its abdomen. It’s a species with a holarctic distribution, found nearly throughout the northern hemisphere. There are more than 5000 species in this family of spiders, which represents nearly 13% of all spider species, the largest taxonomic family of the arachnids.

Jumping spiders have excellent vision, aided by two giant eyes placed on the front of their head, which gives them strong binocular vision, but in a narrow field of view. They have eight eyes total; two others are also located on the front of the head, but the other four are on their back. These remaining six provide the spider’s peripheral vision. They are also amazing jumpers (hence the name of the group). They don’t have the large leg muscles of some jumping insects (such as grasshoppers). Instead, their spring power comes from a hydraulic-like system that uses their interior body fluid (insects and spiders have their “blood” loose in their body cavity, rather than contained in a vascular system) to rapidly extend their legs.

Some jumping spider species can grow quite large; one African species can reach 14 inches in length. These massive spiders have been recorded to jump as far as 7 feet in a single leap. In the larger spiders, where you can clearly see their eyes, you can watch which way they’re looking. This is because the retina of the spider’s eye sits loose at the centre of the back of the “eyeball”, and the spider moves it around, rather than moving the eye itslef, in order to see. This causes the visible colour of the eye to change, depending on where the retina is. When the eye is blackest, the spider is looking right at you.

All spiders are predators, there are no herbivorous spiders. Zebra spiders feed on other insects and spiders that are their own size or smaller. As I stood there and watched this individual, snapping photos, I noticed a small brown spider crawling up the wall towards the Zebra, apparently oblivious.

The Zebra honed in on it right away. It patiently waited for the brown spider to pass it, actually moving out of its way, to one side, to allow it to do so.

Then, once the brown spider’s back was turned, the Zebra lined itself up, gathered its legs under itself…

…and pounced!

The brown spider made it out alive by rapidly letting go of the wall and dropping down on a thread. A happy ending for the brown spider, not so happy for the Zebra.

Going beyond birds

Silver-spotted Tiger Moth

I’ve been birding since 2000, when, as a first year student in university, I decided I wanted a job in my field rather than a boring office job, and was offered an opportunity to work for the Toronto Zoo doing an “inventory” of their breeding bird community. This is not a long time, compared to many birders, particularly given my age. I came into birds late in life; most serious birders I’ve met have started either in their early-teens (13-14 seems to be the age something twigs for a lot of people), or as a young child. Myself, with the rural setting for my childhood, I was certainly aware of the birds, and knew all the common backyard stuff, but the birds that you have to go out to look for in order to see I didn’t get to know till that job at the zoo.

I have had the advantage of having spent a very large portion of the last five years out in the field, nearly every day. When you’re out there seven or eight hours every day you hone your identification skills rather quickly. Just about anything likely to be encountered on an average day at any time of year here in southern Ontario I would feel pretty comfortable identifying now, by sight or even just sound. Some of the less common birds of our region I could identify by sight but perhaps not sound, and I will be the first to admit that some groups (gulls, for example) I generally stink at – though mostly for lack of interest in learning (nothing against gulls, but they just don’t hold my attention for very long).

Lunate Zale

So what do you do when you’ve reached your desired level of proficiency with something? Well, you could try to hone it further (suppose I could buckle down and learn those gulls). You could try investigating deeper (learning to identify the different subspecies). You could travel to new areas (works best if you have money and time to travel). Or you could branch out into something different.

White Underwing

Lacking money and any real desire to get nit-picky with bird identification, I’ve opted for the latter. Even early I started learning butterfly identification (the obvious second choice to a birder – you’re standing there watching the birds with butterflies dancing about your feet anyway), as well as odonates (the dragonflies and damselflies). I got familiar enough with these groups to be able to identify all the common things. But for whatever reason, I never really got caught up in them the way I am with birds.

Pale Beauty

Then, last summer, I traveled west, to British Columbia, for a job. The job didn’t work out quite as planned, and I spent three weeks staying with the organization’s gracious president, twiddling my thumbs and waiting for word on the situation. While there, I discovered he had a blacklight. And I thought, what the heck, let’s throw a sheet up and see what I get.

Violet Brocade

Well, that hooked me. I don’t know what it was, specifically. Perhaps the amazing diversity and beauty of the moths that came in. Perhaps the mystery of these nocturnal creatures that makes them so hard to observe. Perhaps the fact that they’ll come to you, wherever you are, and you never know what you’re going to get. TheMothMan has well over 500 species of moths recorded for his little (and I do mean little) urban Toronto backyard. Perhaps it’s that moths are everywhere.

Ailanthus Webworm

While I don’t think they’ll ever trump birds on my priority list, they may eventually run a close second… we shall see (I dislike making such bold predictions). So far, with the exception of those nights in British Columbia and one hosted by TTPBRS in early September, all my “mothing” has been done in the off-peak (for moths) late fall and, now, early spring periods. The moths are just starting to come out now, on the warmer nights, but these cool-weather moths are generally more drab. The flashy species are mostly found in the warmer months, and I’m rather looking forward to looking for them in the next few months.

Unidentified Eucosma sp.

Doesn’t matter where you live, attracting moths is pretty easy, and I almost guarantee productive (unlike trying to bird from your suburban backyard, where House Sparrows and starlings are your most likely guests). Any night where the temperature is warm (>10C/50F), hang a white sheet from a clothesline or against the side of your building, and set up a light in front of it. Although a regular white bulb will work okay, bulbs that emit rays in the UV spectrum, such as blacklights (cheap, less than $5 at Home Depot) or mercury vapour bulbs (considerably more expensive but brighter so will draw more in) will give you the best success, since the moths are attracted to the UV wavelengths. Make sure your white sheet is the sort that glows in the dark – some types of fabric don’t phosphoresce, which decreases its effectiveness.

Lempke’s Gold Spot

The above photos are all ones I took either in British Columbia, or at the TTPBRS moth night. They’re only a few of what I have, primarily of some of the brighter species. If you’re interested in seeing some of the rest of my extremely modest collection of moth photos (mostly from BC at the moment, and taken with flash; I’m refining my technique), visit my moth set on Flickr.

Peering in the pond, part 2: Signs of life

I picked my way across the little patches of grass and stone, the few areas that aren’t submerged, till I reached the point where the water began to deepen. I squatted down on my heels, peered into the water and saw……

….nothing.

At least, not at first. The water looked still and quiet and empty. I can’t say this surprised me a whole lot; if I lived in a pond year-round, I certainly wouldn’t come out of wherever I was spending the winter until the water was a civilized temperature. Some bubbles floating on the surface cast some interesting star-shaped light patterns on the pond bottom, but that was about all I saw.

And then…

…a bright red water mite zipped across a little depression in the mud. It was the only one, and it didn’t stay out in the open long enough for me to study it or get a good photo. But it did tell me that things were actually awake in the icy water.

So I carefully studied the pond bottom with a bit more scrutiny than the casual scan I’d given it initially. The first thing I noticed were tiny little organisms moving about suspended in the water column (the short amount of it there was). I couldn’t make out a whole lot of detail on them. As I was considering these, a larger movement caught my eye. I also couldn’t make out enough to say what this was, but it was brown and seemed to have a shiny silver eye.

I tried taking some photos of the creatures in the pond, but it was hard to get a good clear shot while they were swimming around, over and under vegetation and detritus. So I ended up getting a bucket and tall yogurt container from the house and scooping out a few containers’ worth of water and pond muck. I couldn’t tell if I’d gotten the creatures of interest or not, but there was really only one way to find out.

The water was very cloudy for the first little while. Gradually as the evening progressed the silt settled out to the bottom of the bucket, but it was still difficult to see the bottom even by the time I went to bed. I could see the little creatures swimming about in the water column, but not the silver-eyed things. I wondered if maybe I hadn’t scooped any up.

When I got up this morning I was delighted to see that the silt had all cleared and I had in fact caught a number of the silver-eyes. The challenge was then how to get them somewhere where I could study them, since I had six inches of water sitting atop the muddy bottom. I ended up using a turkey baster, which was large enough that I could aim the end over the creature and suck it and a bit of water up and deposit it in a little white measuring cup that would allow me to see more details. I set the cup under a bright lamp and poised my camera, firmly attached to a tripod, directly above so I could get some macro shots.

The silver-eyed creatures resembled tiny shrimp, once I got them out of the muck and against a clean background. Less than 2mm wide and no more than a centimetre long for the largest, they had long antennae and many long legs, and curled their tails under their bodies. They scooted about quickly, on their sides just as often as on their “feet”.

This locomotive habit gives them one of their two common names, “sideswimmers”. Their other name is “scud”, which comes from the Norwegian “skudda”, meaning to push. They’re a type of crustacean, belonging to the same family as crabs, lobsters and shrimp, and in fact are sometimes called “freshwater shrimp”, even though they belong to a different group than the shrimp you eat.

They come in all sorts of colours: orange, brown, green, and even silver. These individuals are all likely of the same species, despite the colour differences. There are a few different species of sideswimmer around here, representing a range of different aquatic habitats. I suspect these to belong to the genus Hyalella, which are one of the most common groups. They are so common, in fact, that their conspicuous absence is sometimes used as an easy indicator of lake acidification below pH 6.5 (their tolerance limit). In some streams with ample cover and food it’s possible to record up to 10,000 of these little guys in just one square metre. They eat primarly detritus and help to tidy up pond bottoms. They’re also mostly nocturnal, hiding in the mud during the day, which explains why I didn’t see any while I had the bright light suspended over the water to warm it yesterday evening.

This is the other creature I saw in the pond. If the scuds are tiny, then it’s itsy-bitsy. Only 2mm long, it’s hard to distinguish much detail without a microscope, which I don’t have. The macro lens on my camera allowed me to get a bit closer, but you still can’t make out much detail.

This is a copepod, another type of crustacean. The name means “oar-foot”, and reflects their use of their long antennae as a means of propulsion. This one belongs to the suborder Cyclopoida, the “cyclops” part of the name referencing their “eyespot” (actually two close together when looked at under high magnification), which is used for detecting light. You can just see the small dark dot at the front of the head. The above individual is a female, identified by the two prominent egg-sacs on either side of the body. When she lays the eggs they drop to the bottom of the pool. Some may hatch right away, but depending on conditions, others may settle into the mud and wait. They can survive long periods of drought, and scientists have even discovered and successfully hatched 300-year-old eggs.

I believe this is a male of the same species (although it could be a different species altogether). Males don’t carry the egg sacs and so can look fairly different, particularly when you can’t get a good sense of the whole body shape without a microscope. I’m not sure why the dark upper body; it may be food that it’s ingested recently (the organisms are somewhat transparent and their inner contents can usually be seen fairly easily; for instance, the dark-coloured eggs the female is carrying can clearly be seen through the sacs).

Different species can be either predators of smaller plankton in the water column, or grazers of algae on vegetation or other surfaces. Copepods in general will undertake daily vertical migrations, usually coming to the surface for the night and returning to the bottom during the day.

Flatworm (Turbellaria, genus Hymanella?)

As I was poking around with the turkey baster sucking up little creatures to put in the cup and examine, I spotted something else moving slowly, worm-like, along the top of the mud. I stuck it in the cup with all the rest to have a closer look.

I recognized it right away from my Invertebrate Zoology classes as a member of the group Platyhelminthes, and observed that it was a flatworm, but I couldn’t get much further than that without additional reference. There’s a number of different types of flatworms, many of which have triangular heads. This one didn’t, which helped narrow down the options. I think it may be a member of the genus Hymanella or Phagocata, but who knows, really; my Invert Zoo text is packed away somewhere at the moment, and the other guides I have on hand don’t give enough detail.

Flatworms are incredible contortionists. This one went from being stretched out, perhaps nearly a centimetre long but only a millimetre wide, to short and squat, nearly round and almost 3mm across. They don’t actually swim, but rather move on hair-like cilia on their underside. They’re typically predators or scavengers of microorganisms or other protein sources. They don’t have teeth, but instead use an extendable mouthpart that acts as a suction tube to suck fluids from their prey, or ingest small ones whole. One of the neat things about these guys, that you can actually see in the first picture, is their “crossed eyes”. Like with the copepods, these spots are actually simply photo-sensors, used for detecting light. Another cool factoid: they’re regenerative, and if you cut one into multiple pieces, nearly every piece will regenerate into a new complete flatworm.

That seemed to be about it for my haul, and after I’d taken a few pictures I returned everything to the bucket and then took the bucket back out to the pond where I’d gotten it. I’ll go back in a little bit, once the spring peepers start to peep, to see if the fairy shrimp are out yet, and perhaps to look for vertebrate life.