#cherry destructor

Or in more science-y words, ‘The effect of lead on the metabolic rate of juvenile crayfish, Cherax destructor, under different chronic and acute temperatures’.

Read on if you like cute crustaceans, cannibalism, runaway animals, or lowly undergrad science experiments gone wrong.

For one of my uni courses, Animal Ecological Physiology, our assessment was to design and execute an experiment which investigates a physiological response of an invertebrate to different environmental factors. My group chose to research how acute and chronic temperatures affect the metabolic rates of crayfish which have been exposed to lead (Pb).

Unfortunately, our lack of animal husbandry experience and flawed experimental design left us with shitty, insignificant, and unreliable results. Regardless, here is a little write up on the experience!  #dontworry #welearnedfromthemistakes #yolo 

First of all, crayfish are super cute! (See exhibit A below).

Running the experiment: We were able to use ‘the Glasshouse’ at USYD, inside which we had twelve 10L tanks, each with 3 crayfish, a shelter, some carrots, an air filter, and a tank heater. You’ll note that the tanks are covered over with netting - this is because yabbies are dickheads which will run away mysteriously and cause you to restart your experiment/fuck up your number of replicates if given the chance. Over 25 of our crayfish ran away without a trace! Yabbies can survive for a week with no water, so they may still be roaming the university! 

Taking measurements: After 18 days, crayfish were placed in sealed jars. A small amount of the jar’s water was pipetted into a respirometer and the initial and final oxygen concentrations were measured. Crayfish weights were factored in to get weight-specific oxygen consumption rates.

Another fun fact: yabbies will eat almost anything - including each other! This will further reduce your replicates. Also, once the experiment was finished we were instructed to place the crayfish in a tub elloquently labelled ‘used yabbies’. Also their scientific name is Cherax destructor, which can double as their wrestling/supervillian name.

Conclusions: Yabbies are cute but devious creatures. And --- there are isolated and interactive effects of both temperature (acute and chronic) and Pb toxicity on the metabolic rates of decapods, which generally cause increases in metabolic rates - although our terrible experiment did not find this.