Monday, 3 September 2007

More Than You Can Chew

There is no such fish as a sardine. There is no knowledge of tide or current; no skill with bait or lure that will land you a single species called a sardine, even if there existed a sardine large enough for an angler to want to boast of catching one. The fish more famous for being entombed en masse in oil inside an odd rectangular can, belongs to any of dozens of fish species so treated. The important factor is the small size and palatability. We may choose not to think about it, but sardines have to be eaten whole: head, eyeballs, bones, scales, fins, tail and all.

What we feed to our cat as pilchards might just as easily turn up on our plate labelled sardines. But whether cat or human, the whole fish has to slip down without a snag. Chewing is fine, but a recognizable and resistant bone will have either diner gagging. So sardinability is about being young, plentiful, small and soft-boned. But just in case, there’s always the oil and the heating involved in the canning process to help soften any recalcitrant bones.

The rainbow trout (Salmo gairdneri) is usually another meal deal altogether. It too may be cooked whole, although knife and fork skill is required if you’re to reach the end of a whole trout meal with equanimity. And the head and bones are definitely not part of the meal. That is unless you’re a Tasmanian tiger snake.

New Zealand must once have been visited by St Patrick. Either that or its relative youth geologically-speaking, and its islanded isolation, have meant that few reptiles – and no snakes – have become established on the shaky isles. So Richard promises our kiwi guest the sight of a snake during our visit to Lake St Clair. But it is still unexpected that we should find one on the beach at Platypus Bay. A small adult tiger snake, probably only 150cm long, lies draped around the edge of a wrecked barge in the shallows of the bay. Only 5 metres away, in clear bright sunshine, we have a clear view of its sleek black tessellated form. Unusually it makes no move to flee from our obvious presence. A closer look explains why. On the rotting deck of the old barge lies a rainbow trout, its intense blue spots showing that it has lately been alive. (These spots fade not long after a trout dies.)

We have not witnessed it, but it seems obvious that the snake has just caught and killed the trout. As we stand piecing the puzzle together, some of the pieces begin moving. The small snake appears to be biting the 20cm long fish on its flank. The dining geometry looks impossible, as though a famished Frenchman were attacking a vast baguette side-on using only his mouth.
But a tiger snake has the advantage of a dislocatable jaw, which this one now mobilizes in trying to grip the whole fish in its gape. With slow precision we see the snake manoeuvre the wider fish into line with its greater length. And length is winning out, as the snake’s head, through a process of ratcheted rotations, finally lines up with the fish’s head. In a process that takes a few minutes, the fish begins its final descent into the altogether unwelcome depths of the snake’s belly. As an obvious bulge appears in the snake’s upper neck, a forked fish tail slips out of sight between the reptilian lips. Over the following minutes the snake’s head returns to normal size, its jaw once again hinged, its lips sealed. All that is left of the feral fish is a slowly descending protuberance.

One of our party tells us that tiger snakes are not troubled by water. They will readily swim across a stream or lake, and have been seen to spend up to days lying at the bottom of shallow pools. Presumably they are cooling down, their bodily processes slowed to a minimum in some kind of mini-hibernation. Now it seems we have found out that they not only tolerate water, but that they can even hunt in water. Perhaps fresh water swimmers will be glad that they represent considerably more than a bellyful of protein to the average tiger snake.

- Peter Grant, 22/2/03
Post a Comment