Sunday, February 28, 2010
Saturday, February 27, 2010
Half a dozen moons
Another rainy day. So I went on with my sorting and rearranging old photos. (I managed to delete over 1000 of them; how's that for self-discipline?)
I ended up the evening cleaning out the collection of skies, and found a few that I don't think I've posted before. Moon shots. Perfect for a Skywatch post!
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Susannah (Wanderin' Weeta)
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2:21 AM
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Friday, February 26, 2010
A tale of two hermits
Total amazement!
Every time I pass my little salt-water tank, I stop for a few seconds to see what the critters are up to. Not much, usually; eating, sleeping, digging. The hermits prowl around idly, picking up invisible scraps with the smaller claw, and popping them into their mouths. Limpets on the glass just sit there. So do most of the snails.
Yesterday was different. In the morning, a tiny hermit crab was up at the front, rolling an unattached barnacle over and over. While I watched, he found the mouth, and started digging out the good meat inside. Poor little barnacle!
A minute later, a Japanese Nassa showed up. These are tiny snails, smaller than the shell the hermit was in. Usually they steer clear of the hermits, which can be aggressive when food is an issue, and are well armed. This time, the snail ignored the danger, slid right over the hermit, and glommed onto the barnacle, rolling it over so that the mouth faced the snail.
The hermit struggled to hold the shell, but lost his grip, couldn't get at the meat anymore, and wandered away. The snail returned to the sand, carrying its catch.
I was amazed; the hermit has big pincers, sharp claws on all its feet. And it's not afraid to use them; these little guys will even take on a crab twice their size, and chase the crab off. And the snail is all soft flesh, and that vulnerable siphon; I expected it to be injured, at least, after that confrontation. But the operation was smooth, practiced, economical, the snail sliding over the back of the hermit and onto the barnacle without facing the pincers. An accomplished thief, this one is.
These snails normally hide under the sand, with only the tip of the siphon exposed to catch the scents of fresh food. When they smell something good, they surface. They eat detritus; whatever falls to the bottom, any dead or dying meat, the remains of other critters' dinners. They are often introduced to marine aquaria to help with the cleaning, and to aerate the sand, plowing through it.
That was the morning's excitement. In the afternoon, I noticed Hermit Rex sitting on a rock, acting oddly. He was holding all his legs and pincers close together in front of his face, and scrubbing at them, as if he were itchy. As I watched, wondering, I saw the reason; below the face of the rock, there was a ghost, a pale, shadowy copy of Rex.
Rex had just finished molting, and was getting his limbs limbered up. I watched him until he turned and left, then I retrieved the husk he'd left behind.
The old carapace was intact, except for a small, round hole at the back of the thorax. Rex had pulled himself, eyestalks, antennae, pincers and legs, through that hole. It is about half the diameter of his big pincer. The abdomen is missing; hermits don't wear a crust there, substituting it with a borrowed shell. So there was no need to shed the skin of the abdomen. It stretches just fine. It's the crusty part that gets too tight when the hermit grows.
More amazement; the eyes are still there, still glassy. All the various appendages are in their proper places. Even the various joints and angles of the mouth parts and legs are intact. And he had pulled long antennae out of the centre of the old antennae without breaking either; how was it possible?
I only wish I had stopped to look a few minutes earlier. I would have loved to watch the process. Maybe next time.
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Susannah (Wanderin' Weeta)
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1:39 AM
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Labels: hermit crabs, molting, Nassarius, sea snails
Thursday, February 25, 2010
Comparing Februaries
Our hedge, February 26, 2009:
Our neighbour's garden, February 20, 2010:
Of course, it still could snow by tomorrow. In BC, you never know.
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Susannah (Wanderin' Weeta)
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2:29 AM
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Wednesday, February 24, 2010
Copepods in love
I've been chasing copepods in a few drops of sludge from my aquarium filter, trying to get a decent photo; they are so cute! So tiny! And so busy!
Busy, mostly, it seems, with starting families.
I found several couples like this one. One follows the other, nose to tail, never giving up. I assume the female is the one in front. Mostly, single copepods wander about almost randomly, now slow, now stopping, now dashing off in another direction. These pairs zip around at top speed, always connected.
Courtship and breeding is a long affair for such "simple" critters. First, the male must get a good grip on the female. He may (according to the species) need to convince her first, which might take up to two weeks. Persistence counts.
Once she has submitted, he produces a spermatophore, a container filled with sperm. This he glues to her genital field. Then he may guard her, keeping off other males, until her eggs are fertilized.
After a few hours or days, she produces an eggsack or two (depending on the species, again). Now, she is obviously a female, even to us non-copepod observers; the eggsacks are almost as big as she is.
I couldn't tell if this one had one or two eggsacks. They were carried beneath the body, with the transparent, pinkish tail swishing back and forth over it.
These larger females (twice the size of the little ones, at 1 mm. long), carry the two eggsacks off to the side. They are not as strongly coloured, so often all that is visible in the muck are the two blue-green bags.
A few days later, those eggs will hatch and she will jettison the empty sacks. The spermatophore may still be attached, and will fertilize the next batch of eggs, too.
I trapped one last December: there's a photo here; it's an adult, either male or non-breeding female. The rest of the life cycle is described in this post.
The University of Oldenburg has more info, and some good close-ups. (Click on the labels at the bottom for more.)
Posted by
Susannah (Wanderin' Weeta)
at
3:59 AM
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Labels: copepods, intertidal zone, invertebrates, reproduction
Tuesday, February 23, 2010
Local colour
Marigold yellow, winter sunset yellow, raingear yellow. And BC skies grey.
Posted by
Susannah (Wanderin' Weeta)
at
12:37 AM
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Monday, February 22, 2010
Singing reeds
The red-winged blackbird males are back, and staking their claims. Konk-a-ree!
In the picnic area of Centennial Park, there is a small duck pond. The designers thought of everything; weeping willows at one end for shade, dead snags for perching birds, sloping, grassy slopes for ducks, and a tiny island in the centre, covered with tall reeds for nesting in. The island was singing. Konk-konk-konk-a-ree! Hidden redwings, all shouting at once.
When the females arrive, in a few weeks, the males will take to the tops of the reeds to warn off intruders. For now, they're just voices. I saw one, near the roots, barely a smudge of black with a shining eye.
Laurie noticed a shoveller, at the far end; the first we've seen for a long time.
The tide was out, and we walked and waded half-way across the sand. A few more mallards dabbled in the shallows here, and an eagle tore at something at its feet. Gulls dotted the sand in every direction.
All very static, so far. But then there were these ...
Cavorting silently, mind you; it was the redwings' day to sing. (Crows don't count; they don't sing, they croak.)
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Susannah (Wanderin' Weeta)
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1:38 AM
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Labels: birds, Boundary Bay, Centennial Park, crows, ducks, redwing blackbirds
Sunday, February 21, 2010
Two-faced hermit?
Rex was watching me again. I got down and stared right back at him, eyeball to eyeball. But what's that? Four eyes?
It almost looks as though he has a second, smiling face under the eyestalks. A vertebrate sort of face, not crab-like at all.
I don't know what the second pair of "eyes" really is. Doing inventory; he's got the eyestalks, the long antennae off to the sides, the antennules between the eyestalks, two sets of maxillipeds for eating ... isn't he supposed to have three? So the "smile" must be the third, and smallest set of maxillipeds. But what are those "eyes"?
I took the same photo twice; this one in natural light, through the window, the next one with the flash. Look at the difference it makes!
The flash gives a sharper photo, and brings up the detail better, but it eliminates the translucence of the eyestalks and antennae, and the glow of the backlight. I think I like the first one more.
What do you think?
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Susannah (Wanderin' Weeta)
at
2:49 AM
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Labels: hermit crabs, macro photography
Saturday, February 20, 2010
Just another beachy afternoon
White Rock, Thursday, as the tide was coming in:
Oh, and along the road home, the camellias and rhododendrons were blooming. February or no, it's spring.
Posted by
Susannah (Wanderin' Weeta)
at
12:30 AM
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Labels: crows, dogs, spring, White Rock
Friday, February 19, 2010
Better than Rio; three carnivals!
I and the Bird # 119 is up, Somewhere in NJ. Read it twice; once for the essay, the second time round checking the (almost hidden) links.
And the first edition of the beetle carnival, An Inordinate Fondness, has been posted. Yay! A great start, crawling with beetles. I never imagined that a carrion beetle could be so beautiful.
And House of Herps #3 takes us on a ride in a time machine. If you don't mind a bit of an overshoot at first, before Jason figures out the controls. (I didn't have anything for this one; it'll be months before I get to see a snake around here. Does the time machine run forward, too, Jason?)
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Susannah (Wanderin' Weeta)
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1:47 PM
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Labels: An Inordinate Fondness, beetle, carnivals, House of Herps, I and the Bird
Flatlands
The Fraser River splits into two arms as it enters the delta. Between them lies Richmond, with another split in the northern arm making a separate island for the airport and Iona Beach. It's flat, low-lying land, as befits a delta. Half of it, more or less, is residential and business; the other half is farmland, growing mostly blueberries and cranberries.
Across the river to the south, is the municipality of Delta, stretching from the Fraser to Boundary Bay to the south. It's the largest municipality in the Greater Vancouver Regional District, flat and boggy like Richmond, but sparsely populated. North Delta, where we live, is off the delta proper, up on the hillsides; most of the people live up here. Below are farmlands, Burns Bog, and a lot of empty space.
I measured the flats on Google; from Reifel Island at the northwest corner to Burns Bog to the Nicomekl River on the south, and back along Mud Bay to Tsawwassen, then up to Reifel again for the fifth side of a kid's drawing of a house; as the crow flies, about 40 miles. Following the roads, it's about 60.
We criss-cross this area on our way to most of our favourite shores. We don't usually stop; it's a long drive already. Often, we take photos from the car windows. Blurry photos, mostly. Not all.
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Susannah (Wanderin' Weeta)
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3:40 AM
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