Aug 29, 2011

Rat Dissection - gory but good

But first...
I realised the other morning as yet again I loaded snacks and yummy things into our little basket, that like the proverbial army, homeschools run on their stomachs. This winter we have tried to have an outside morning tea every clear day. It cheers everyone up, especially me as after fruit and homemade (sometimes store-bought) snacks and chatting the girls run and play while I poke around and meditatively weed the vege beds.

Dissection photos ahead - sensitive souls avert your eyes ;- ) 

Have chickens, expect rats
We have chickens, we feed them grain and kitchen scraps, and as a result we also have rats. 

Rats are a hot topic at the moment as we are reading Kenneth Grahame's "Wind in the Willows" from the Michael Clay Thompson's new Language-Illustrated Classic edition. We are all loving the book (and the extra MCT notes sprinkled through the text).

Rats are clever creatures that are difficult to keep out of the chook food. We fixed that by using old dishwashers to store the grain...But then they just moved their home to under the chicken shed itself - now netted with bird wire to keep the wedgetail eagles out (see more of our wedgie in the chicken pen story and video here). Sadly this means beautiful night-time avian predators like the sooty and whistling owl can't get in to cull the rats and their many, many babies.

We won't use regular poison as it is a slow agonising death, and runs a hugh risk of a secondary poisoning of predators or carrion eaters like goannas.

What to do?
The rats started eating our snow peas, the tops of the asparagus, the strawberries are starting to form, and that did it for me...the rats had to go.

Now I am a country girl and a realist - there will of course be more rats that move in once these ones are gone and I am ok with that. We just needed a method that would suit our humane kill requirement (relatively speaking of course).

Car fumes death
Cue this wonderful American PDF book on dealing with pests. Poring over it, Mike and I chose a method - suffocation by car exhaust fumes - and off my darling husband went to do the job. He blocked up all but one hole leading under the slab, drove the car around, attached an old vacuum cleaner hose and placed the nozzle in the last hole. 

Be safe - outside only!
Naturally, this was all done outside in the open air! This method only works with rats underground and human safely outside.

Half an hour and 8 rat bodies later (plus at least the same again under the concrete floor I suspect) the chicken pen is rat free! The fumes are heavier than air so sink into the underground burrows. It is quick and apparently sleep was certainly effective. November was fascinated with their bodies and asked excitedly "Can we dissect one after lunch? Please???"

Of course the answer was yes! This is the part of unschooling or child-led learning that I like the best. We are an "eclectic" homeschool and while we do have bits I like us to do week in and out, we often throw the rough plan out the window to follow the girls' lead and why not?

We had already done some spelling before breakfast, then super-thinky work in maths and Language Arts with Michael Clay Thompson's "Grammar Island" after morning tea. We were all due time outdoors reading or about cutting up a dead rat?

Naturally, a quick look on the net and I found a great web based step by step on Educatus to look at on the iPad. November then watched this youtube video (see above) on rat dissection as preparation. We also checked out the fetal pig colouring-in pages from the wonderful "Zoology Coloring Book" as an warm-up for understanding the anatomy of mammals.

Gather tools
I naturally had a couple of scalpels and blades lying around ready (truly - though just a leftover from art projects years ago but in use a lot around here), tweezers, bamboo sticks to use as probes, protective goggles, latex gloves, and an art pinafore. Mike did all the blokey stuff with hammer and nails, stretching the rat out on a cork tile. His pointy nose pliers completed the equipment. 

Mike made the initial incision...

Then over to November! Here are some photos.

Inspecting the liver, stomach and intestines:

Cutting through the cartilage to open up the rib cage...

Heart and lungs open to view:

And still not completely satisfied, with Mike's strength, she skinned the rest of the rat, freed the  spine from the skull and then pulled the tail from the skin. 

November was able to see how the vertebrae continued all the way to the tip of the tail...

At the end of the dissection, the rats body was returned to the bush for other animals to finish off. November did thank the rat, by the way.

Following up with written material for retention and understanding
Once completed, November was still keen for more, more, more, so I found a few more worksheets on the net including this beauty from John R. Sowash.

Happy days - when horrible pest becomes education helper. 

Thanks Ratty - very much appreciated.

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