Over the past two years that I have dealt with Dissection Connection I only have great praise for the specimens that they supply. My teachers always comment on how wonderful the specimens are because they are so intact and whole clearly demonstrating all the structures of the particular organ. Dissection Connection service is second to none always providing wonderful and friendly assistant and delivery. With a great sense of humour added, Dissection Connection is a wonderful organisation to do business with. I highly recommend them to any school, college or university requiring excellent specimens for dissection, demonstration or observation.
To help satisfy the demand for whole animal specimens we’ve decided to stock cane toads. Mr Vivi has been collecting and packaging toads all summer and we now have a freezer full of the hoppers. They are packaged individually and identified by sex. So, consult the current price list and choose whether you want boys or girls. Available until they run out and collection starts again in spring.
Cane toads. Female on the left, male on the right. Notice the distinctive markings which can be partially used to sex a toad.
Dissection
A cane toad dissection allows the biology teacher to cover many aspects of body systems including, skeleton, musculature, heart and arterial, venous, digestive and respiratory, urogenital and nervous systems in a series of practicals using the same specimen. Dissection Connection stocks cane toads with a snout vent length (SVL) of over 80mm that have been sexed and packaged as individual male and female specimens. In stock soon, ‘The Zoology Coloring Book’ by Lawrence M. Elson to compliment your class.
Many methods have been suggested. Step-wise cooling and freezing was for some time the recommended method but recent work has found this method can cause distress and pain to the animal evidenced by behavioural responses to this and other methods. One of the mechanisms that cause pain in this method includes freezing in the blood, producing ice crystals that are transported around the vascular system and cause pain.
A joint project between The Australian Government, The New South Wales Government and The University of Wollongong (CAN001 Methods for the field euthanasia of cane toads, T. Sharp, A. Lothian, A. Munn and G. Saunders: 2011) found the preferred methods were:
stunning followed by decapitation
gassing with carbon dioxide (CO2) for >4 hours
Due to the numbers handled and the requirement for an intact specimen for dissection, Dissection Connection has opted for method 2, gassing with CO2.
This CO2 euthanasia SOP is that recommended on the Queensland DETE animal ethics website and by Biosecurity QLD. We follow the procedures in the original scientific paper which outlines a number of extra steps that DETE don’t mention.
Specimen preparation
After successful euthanasia, toads are measured. Only those with minimum snout-vent-length (SVL) of 80mm are kept. Toads are sexed as per Narayan, Christi, Morely and Trevenen (2008) based on external morphological features and presence/absence of vocal sac openings in the mouth.
Toads are then set in trays, frozen overnight and vacuum packed.
Workplace health and safety
Use nitrile or chemical gloves to handle, NOT vinyl gloves for handling toads. I used vinyl gloves for about half an hour handling dead toads, my fingers were tingling for about an hour afterwards.
Nitrile gloves should be used when handling dead toads and conducting dissections as toxins may be present on the skin of the toad.
Have fun with this, it’s a great dissection!
References
Narayan, E., Christi, K., Morely, C., and Trevenen, P. (2008). Sexual dimorphism in the cane toad Bufo marinus: a quantitative comparison of visual inspection methods for sexing individuals. Herpetological Journal 18: 63-65.
Sharp, T., Lothian, A., Munn, A. and Saunders, G. (2011). CAN001 Methods for the field euthanasia of cane toads
What holds a pig up? The internal skeletal system in the Kingdom Animalia, sub-Phylum Vertebrata, which includes mammals (pigs), fish, amphibians, reptiles and birds has many functions.
Cervical vertebra. Includes 7 cervical vertebra (atlas, 2-7), 4 thoracic vertebra and the first 4 sternal ribs. There are always 7 cervical vertebra in pigs (and humans). In Figure 1 you can see the spinal cord and vertebral disks too!
Figure 1. Cervical vertebra. Articular and transverse processes on the lateral side of this specimen (hidden) minimise excessive bending of the neck, protecting the spinal cord.
Thoracic vertebra. The specimen shown in Figure 2 includes 9 thoracic vertebra, ribs, vertebral disks and spinal cord. The number of thoracic vertebra varies between pig breeds from 13-17. Where do the ribs attach to the vertebra? Find out this one time only, $6.00.
Figure 2. Thoracic vertebra with elongated dorsal spines.
Figure 3 shows the shoulder joint. It includes the scapula, humerus and fused radius and ulna. One only in stock at the moment, $6.50. If you need more than one Miss Vivi can order these for you.
Figure 3. Shoulder joint with humerus and fuses radius/ulna.
Loin chop (Figure 4). NOT FOR SALE – it’s for Mr Vivi’s dinner. But you can see the elongated transverse process on the lumbar vertebra (the bone pointing to 8 o’clock) that supports the strong muscle (yummy meaty bit) that in turn supports the viscera in the abdominal cavity.
Figure 4. Loin chop showing elongated transverse process. The muscle above the process is the loin, the smaller muscle below the process is the tenderloin muscle.
Pig tail (Figure 5). Tail bones are called caudal bones. The number of caudal bones varies between species of pig between 20 and 23. How many does this one have? Find out for $5.00
If you have the need for bone specimens for a class in science or physical education, get in contact with Miss Vivi as she can source a wide range of specimens as a special order.
Teaching science can be a tough gig. Most of the time teachers feel that they are time poor and content rich. Fitting everything required by the curriculum into a term can feel like herding cats into a bag.
Teachers know that kids want to explore science more than be taught it, but often it’s just not possible to let them take as much time as they need to really get as much learning out of an experiment as they would like.
That’s why I’m over the moon when I hear that a class has had the time to really get more bang for their buck out of one of our specimens. These photos have been sent by a labbie who bought them for a teacher wanting to teach about the brain and spinal cord. We decided that piglets would be the best option to teach this and the kids were enjoying it so much that when they were finished looking at that they flipped them over and got into the abdominal organs as well. Truly a case of learning about everything but the squeal.
The labbie says:
“They are an excellent class. It was great to see how involved they were during the prac. They really enjoyed it!
Because this dissection took place over just one period, I was requested to prepare the piglets prior to the prac, exposing the brain and the spine. … We couldn’t get hold of a Dremmel at the time so, used a hack saw to cut a cross in the skull then, cut the hole out with a pair of kitchen scissors. He also suggested that a Dremmel would be perfect for this job. It’s been put on our list for purchases prior to the budget rollover.
I then prepared the others which made it quicker and easier for the students to then get to where the brain stem and the spinal cord meet since that was their main aim for the prac.
After that the piglets were dissected even further as you saw, to locate and expose all other organs in the stomach cavity etc
All of our Science staff were extremely impressed on the quality the specimens you sent.”
Piglet prepared for the class with spine and ribcage exposedBrain of the piglet exposedBase of the skull being openedBrain stem of the piglet being examinedSpine of the piglet exposedAbdominal organs in the piglet
Before we sent the piglets we had a bit of discussion by email about the best course of action for this prac. I still don’t have a Dremel and haven’t had a go at it, but this is what we suggested:
We believe that the best tool for opening the skull will be a small circular saw called a Dremel available at hardware stores. I was speaking to a very experienced biology teacher … that runs an extensive comparative anatomy program in his Yr 12 classes who agrees that they are the tool for the job. I am going to buy one and have a go myself. Do be careful because the skull will be slippery. You will use the Dremel to score the skull and then need a chisel and hammer to ease the skull open. There are some very good videos on YouTube that will show you what to do.
To expose the spinal cord at the back of the neck you will need to cut into the skin on either side of the spine at the base of the skull and lever the section away from the body and towards the tail. You will also be able to view the spinal cord and spinal nerves by opening the abdomen of the piglet and removing the organs to expose the spine. You will be able to see the spinal nerves entering/exiting the spinal cord cavity between the vertebrae – lift them with a probe. The vertebra will be soft enough to slice the top off with a scalpel and you will be able to view the spinal cord in-situ.
This website is an excellent resource for piglet dissections and the skull and spinal cord sections are very clearly described with photos. http://www.whitman.edu/content/virtualpig
