a study in snoek

Patrick caught two beautiful snoek (Queen Mackeral) off his fishing ski this past weekend. What a privilege to be able to enjoy a healthy meal of fish, fresh from the ocean. We gave half to our neighbours who turned it into a delectable meal for their family that evening.

Whenever Patrick gets back from his morning's fishing, he cleans and guts the fish straight away.

This time I asked if we could turn it into a lesson for the children (and the neighbour's children), because we happen to be in the middle of a marine theme in our studies. I thought it would be fantastic for them to actually see the parts of a fish first-hand.

Warning: Some of the photos are graphic - and may offend very sensitive viewers.

So, I made us each a cappuccino coffee, and got the Sea Fish Guide off the bookshelf, so that we could identify the different organs as Patrick prepared the fish.

He cut off the tail first, and then carefully cut off a lovely thick, boneless fillet from each side of the fish. He wanted to get the flesh into the fridge as quickly as possible so that we could take our time dissecting the rest of the fish.

The neighbour's children were a little worried and uncomfortable at first, but their fascination soon overcame their squeamishness!
I just love the body language - don't you? :o) One of the first things we identified was the Lateral Line. This line runs down the length of the fish, and is an amazing sense organ which helps the fish to detect movement in the water around them. There are receptors in this line, called neuromasts, and they in turn contain hair cells, similar to the cells found in our ears, which pick up vibrations and wave movements.

The line can be seen running from just behind the gill openings towards the tail, at the top end of the fishes body.

Here is a closer look

Next, we looked at the gills. What an efficient breathing system! Water is taken in through the mouth of the fish and passes through the intricate filters which extract the oxygen from the water, before it passes freely out of the gill openings.

We all felt the beautiful, soft filters of the gills and proclaimed our amazement at their design!
Nestled in just behind the gills is the heart.
Hard to believe this tiny little organ is responsible for such a big task.

Here is another shot of the heart on the right, with Patrick's thumb under it, and a great view of the gills again.

We then established where the brain would be situated, and Patrick cut straight through to get a cross-section.

Perfect! You can clearly see the two halves of the brain, with the spinal cord coming from it.

The boys all exclaimed that it looked just like a guitar!

Interesting to note that the brains of all bony fish are divided up into three parts: the forebrain, the midbrain and the hindbrain. The forebrain is responsible for the fish's ability to smell, so fish with a good sense of smell, like the eel, have an enlarged forebrain. The midbrain is responsible for sight, learning and motor responses. The hind brain is responsible for co-ordinating movement, muscle tone and balance - so fast swimming fish (like the Snoek) have an enlarged hindbrain - which is why it looks like a guitar!!

We did look at the internal organs like the liver, kidneys and stomach as well - but I'll leave those for another time. Usually it is fascinating to cut open the stomach and discover what the fish has been eating (Patrick uses this as clues for what bait he should use!), but this time the stomach was empty, which is why this fish came on the bite so quickly - he must have been hungry!!

Lastly, we dissected the eye, but I'll spare you those rather gory shots. :o)

I did, however want to show you the lens ...

Isn't God's creation amazing!