More crayfish shenanigans

I went into the field with Kat again yesterday, doing some more crayfish work. You can read more about her work in my Crayfish tracking post. Kat’s been training a sheep to help her track down crayfish, and it proved to be a complete success.

Kat’s crayfish-tracking sheep earned its keep within the first few minutes of our arrival

This time we were trying to refine some temperature logging methodology. Kat needs to record body temperature in her crays when they come out of the water. The easiest way to do this is to glue a small data logger onto the side of the cray’s carapace. But we don’t really know if this will give an accurate representation of temperature. Crays are ectothermic, so their body temperature may be the same temperature as the environment. But if they thermoregulate (control their body temperature by behavioural means like basking in the sun to warm up, or by physiological means such as shunting blood away from their body surface to prevent radiative heat lost) then their body temperature will be different to that of their environment. So yesterday we were trying to conduct an experiment to see if a data logger stuck to their shell accurately depicts their body temperature.

To do this, we stuck a logger on their shell, a thermocouple probe up their bum, and another probe stuck to their underside. We shoved them in some creek water (about 17 degrees Celcius) and let them chill out for a bit. Then we took them out and placed them under an incandescent lightbulb and allowed them to heat up slightly. Every 30 seconds we’d record the temperature from the thermocouple probes. After 10 or so minutes we’d stop, and remove the loggers. The idea is that Kat now downloads the temperature data from the loggers, and sees how closely the temperature readings from all three sensors matches up. Hopefully the temperature recorded by the logger stuck to the side will be close to the cray’s internal temperature, as sticking a logger on a crayfish’s shell is much easier (and no doubt far more comfortable for the cray) than shoving a probe up its clacker.

It’s been raining a lot recently around the study site (and it was still overcast and drizzling yesterday), so the creek was full. Very full. And flowing very fast.

A raging rapidy river

I thought that the fast-flowing water would prevent the crays from coming out, but apparently not. They seemed to love the conditions, and were out in force. For the first time I got to see crays out and about on land.

A cray we found out on the land

Slightly closer, but no less angry

It’s not uncommon for these crays to be found hundreds of metres from the nearest body of water. They roam around at night, presumably foraging or looking to move to new waterways. As Kat and I were walking around on dusk we found two medium-sized adult crays walking about 10 metres away from the creek. As soon as they saw us they raised both claws and started hissing at us.

Throughout the day we also saw lots of crays in the water. They were in the new, slow-moving pools of water that formed as the water level of the main creek line had risen. These new pools would represent new habitat, and a source of new food as the creek rises and covers lots of organic material.

I saw lots of little skinks, but didn’t manage to get any photos. I think there were all some sort of Saproscincus. I did manage to get a photo of a frog. A blurry photo of a frog, but a photo of a frog nonetheless. It was dark, and I couldn’t see where the frog had landed, so I just pointed, pressed the button, and hopped for the best.

A blurry Litoria wilcoxi

After consulting with my good friend and Stewed Thoughts’ resident frog expert Steve Weir, I’ve found out that this frog is probably a species within the Litoria lesueuri complex. Here’s some more info from Steve:

L. lesueuri was split in 2004. I’m sure your frog is not the now defined L. lesueuri (blue thighs), and I’m also sure your frog is L. wilcoxi (yellow thighs). See that bit of yellow and black patterning in the groin? My ID is also based on the distribution. Have a look here for a bit more info. Based on the colouration I’d also suggest a female. There are a few other frogs similar to L. lesueuri, such as L. latopalmata and L. brevipalmata, but the habitat is wrong, as is the groin colouration. Here’s a favourite link of mine on Brisbane frogs.

Thanks Steve! Steve is available for weddings, BBQs and Bar Mitzvahs.

The thing about rainforests, you see, is they tend to be damp and cool. Because of the rain. And leeches like damp, cool environments. And they like toes too, apparently.

The aftermath of a killer leech attack. Are Kat’s toes abnormally hairy?