Wednesday, December 20, 2006

Bad bee photos

Took some quick snaps of the variety of native bees visiting some flowering Angophora bakeri yesterday morning. Nothing I was really too proud of in the bunch, but I thought I'd share a few of the photos anyway. My main problems were lack of sharpness (too much sunlight - so the flash no longer froze the motion of the bees and camera shake) and lack of good poses (well that's what I get for spending so little time on the job).

The only IDs I'll attempt are:
No. 3: Lipotriches sp.
No. 4: Yellow-spot bee (family Colletidae, Amphylaeus, Hylaeus or Meroglossa sp.) plus one of the red bees, Lasioglossum sp. a Homalictus species, possibly H. brisbanensis.

Camera batteries are charged and I'll have another go when the weather fines up.

Tuesday, December 19, 2006

Didymuria violescens

The phasmid species that I wrote about that showed phase change appears to be Didymuria violescens. This photo is of an adult male - I also have some females that have just reached adulthood.

This page lists 'purple winged stick insect' and 'spur-legged stick insect' as common names. I've actually induced one of the males to do a defensive/startle display where it spreads its wings, showing off the purple membranous hind-wings. The habitat seems to match; the page also reports that the species tends to be found at high elevations.

Monday, December 18, 2006

Leaping larvae

Snail mentioned "cheese-skippers", the jumping maggots of the carrion flies (Piophilidae).

It's slightly less obvious why piophilids are called cheese-skippers. You need to see the maggots at work before the common name makes sense. When disturbed, they curl up, grabbing their ... ahem ...anal papillae with their mouthparts. And then they let go, springing several centimetres into the air. Boo!

Jumping in dipteran larvae additionally occurs in several other, taxonomically diverse families. These include Tephritidae (fruit-flies), Cecidomyiidae (gall midges), Agromyzidae (leaf miner flies), Clusiidae (umm...?) and Phoridae (scuttle flies). (Phew, those are a few fly families that you don't come across very often! I wouldn't know a cecidomyiid from Adam!).

Additionally, jumping has been noticed in the Neriidae (long-legged flies). The neriid that occurs in Sydney is Telostylinus angusticollis. This animal is cultured at UNSW and used for studies of sexual selection and aging, as the males have exaggerated features and fight for resources and access to females.

That's a female pictured on the left; males are more slender and elongate. They fight head-to-head, striking each-other with their front legs, heads and antennae. Males also put those long legs to use standing guard over a female - literally.

Larvae of the species, pictured top and bottom, develop in rotting bark, such as that of Acacia longifolia. When they are close to pupation, they evacuate the gut, emerge from their substrate, and at this stage are thought to use jumping as a way of getting off their tree and getting to the soil where they are thought to pupate.

This photo shows what a larva looks like before (left) and after (right) evacuating its gut. Only when it's done this does it gain the ability to jump.

You can see the mechanism in the top photo - the maggot reaches around, grabs a 'ledge' between its last two abdominal segments using its oral hooks, then it contracts its longitudinal muscles. This builds up tension which is then released when the oral hooks are disengaged. Pop!

They're not terribly good jumpers. Not like piophilids which can jump about 50 cm from the surface of a corpse. No, these guys have a lot of trouble jumping from a horizontal surface. They actually do it best if they're upside down - they'll hang off, suspended by their rear ends, before reaching up and jumping downwards off the surface. But put one on a dry surface and crawling doesn't work, so it will wriggle around and try to jump. Normally it doesn't work so well (as in the top photo), as the larva will be lying on its side and therefore not have a great deal to push off.

Jumping in fly larvae is a novel solution to the problem of moving fast and far if you're a small soft-bodied organism. The place where the larva grows up, be it rotting bark, a piece of fruit or a decaying corpse, is generally not a great place to pupate. And a juicy maggot in the open is vulnerable to predation, parasitism, dessication... With a couple of quick jumps, a larva can get away from its food source without crawling laboriously over its surface, settle down and start the business of metamorphosis.

Friday, December 15, 2006

Friday Frog - Amplexus

This image was taken a couple of months ago of a species called the Whirring Treefrog, Litoria revelata, from the mid-north coast, where it's relatively abundant in some areas, though it's not a commonly encountered frog in general.

This photo shows, of course, the hold called 'amplexus' where the male (the little yellow fellow in this case) grasps the female in preparation for oviposition. The poor female then has to drag the male around to the spawning site(s) she chooses. Amplexus is either axillary (the male grasps the female in the armpits) as in this species, or inguinal (around the waist).

Male Litoria, at least in my experience, often seem to take on yellow colouration when they're trying to find mates. A classic example is of course the ground dwelling species L. lesueuri and similar. I wonder if it's some sort of advertisement?

Litoria revelata has a high-pitched whirring call, sort of like a sped-up version of the closely related L. verreauxii. At the site where these two were photographed, they can occur in huge numbers, and it's absolutely ear-splitting when the frogs are really going for it. It also seems as if the other species that occur at the site just give up - and shut up - rather than try to compete over the din.

Saturday, December 09, 2006

Jumping Spider (quick photo)


check out the new Circus of the Spineless - #15!

Broughton Island

Looking South-east from Pinker Top.

Broughton Island, sized a couple of kilometres across, sticks out of the ocean north-east of Nelson Bay. I recently paid it a visit to do some volunteer work for an ongoing frog project that's being conducted on the island. It was a great place to visit, truly the location made the work much more pleasant.

Esmeralda cove

The island is part of the Myall Lakes National park, but there are several shacks looking out over Esmeralda cove, owned by fishing clubs and leased from the park. No-one's supposed to live there permanently, but some of the blokes seem to spend a good part of the year on the island.

Flat rock

Believe it or not, this photo above is of the best frog site on the island, and it's home to several hundred Green and Golden Bell Frogs (Litoria aurea), the endangered frog that caused venue headaches during the planning of the Sydney Olympics after it turned up in the Homebush Brickpit. There are numerous small ponds on that rock platform, fed by seeps of fresh water. Every now and then a big wave inundates the ponds, killing any tadpoles and other aquatic life. It's a crazy place for frogs to survive, but bell frogs are notorious for doing well in habitats with regimes of regular disturbance, in fact they often seem to be out-competed in static ponds.

Green and Golden Bell Frog (Litoria aurea) on prickly pear

Bell frog on algal mat

Apart from bell frogs, the other species of frog that's on the island is the Striped Marsh Frog. Stripeys are a very common species in suburban Sydney, but are in lower numbers than the bell frogs on this island. There's a handful of reptiles on the island, introduced rats and rabbits, and a nice array of sea-birds. The little penguin colony that exists there is the northern-most population of the species. Numerous Mutton-birds call from their burrows at night, and seem very confused when encountered on the paths that cross the top of the island.

Little (fairy) penguin

Sooty Oystercatcher

Looking back towards Esmeralda cove

One final bell frog

Panoramas compiled using Autostitch v.2.186