Tuesday, May 12, 2009 ;
The kindy is doing a unit on marine environments now. Their teacher knows I was a Biology teacher, so asked me if I could come in as a parent volunteer/ guest speaker and show the kids some marine organisms coupled with showing them the external and internal anatomy.
It sounded really fun. I get to spend money buying organisms in the market (which is not my money) and get to learn more and share interesting nuggets with others, why not?
So I agreed. H kindly brought me to a big wet market, and I saw so many suitable live and freshly dead sea creatures. After I told the teacher, she suggested having a representative from vertebrates and invertebrates each cos the kids have been talking about the presence of a backbone.
I bought a cuttlefish that day last week to try out first. (I hadn't done dissections since 2006, and we seldom perform them on marine animals. Usually it was organs like the eye, heart, kidney of mammals, and then on whole mammals.)
It was a huge one, but the market had larger ones! That's my rudimentary dissection tool - kitchen knife. Instead of dissecting tray, a bamboo chopping board. hee.
I took out the beak of the cuttlefish, and washed and dried it. Packed into ziploc for the kindy class to compare with the squid's. The 8 arms and 2 tentacles can be seen clearly here too.
Difference between squid and octopus: octopus also has 8 arms but no tentacles. Both squid and cuttlefish have 8 arms and 2 tentacles.
How to tell tentacles apart from arms. Arms are shorter with suckers all along. Tentacles are smooth till the end part where there'll be some suckers.
Suckers in squids may have chitin rings and some other weaponry, whereas suckers in octopuses do not. (That's why sperm whales, the natural predator of giant squids, are often found having ring-like scars all over their skin near the jaws. They are sustained while they attack the giant squids, and the squid wrap the arms and tentacles around the sperm whale's head.)
This is cuttlefish. They have suckers too. More similar to the squid than octopus.
Very unprofessional cutting with the kitchen scissors. But still, with a lot of due respect and dignity for the cuttlefish. We got a huge surprise!
There was a whole fish and whole prawn inside the mantle cavity. Usually cuttlefish attack their prey by shooting out their tentacles then bringintg the prey to its beak. It'd drill holes into those with shells, or tear apart the prey if it doesn't have shells. Then it'd feed on the prey, pushing the smaller parts into the mouth.
Dh and I were hypothesizing, why there would be the fish and prawn in there. What a good deal we got!
Close up of the fish, prawn, the funnel, ink sac, gonads and mantle flaps.
Then I took the beak out from the mouth. Really resembles parrot beak. Its pointy end can really tear the prey up, for sure.
Proceeded to the back. The skin has a lot of chromatophores and other -phores that help the cuttlefish to change its appearance, or for bioluminescence. That's why the cuttlefish, squid and octopus are masters of camouflage. Their mechanism is far more complex than the chameleon's.
Inside, the cuttle or cuttlefish bone can be seen and isolated. It's a good source of calcium so they are often left in bird cages for the birds to peck at. For the cuttlefish, it helps in buoyancy (air pockets), adjusting its depth in water and also some kind of support, I guess.
What the insides look like after extricating the cuttlebone.
After I had identified whatever I wanted to, we disposed of it. Actually we could cook and eat it, but no one was interested. Dh didn't want to eat it, and the kids and I don't appreciate it.
Was a good introduction to the actual thing I had to do the following week.
rainbows every day, do not worry for the morrow