How many fish can you see?

January 2010

One Jumped up, One Pumped up, Both Dumped up

This numbfish washed up on a Moreton Island beach with a porcupinefish stuck in its mouth.  How did this happen?

Answer

The unlucky numbfish grabbed hold of a porcupinefish and tried to swallow it. In self defence the porcupinefish has inflated, embedding its spines in the numbfish’s mouth.  The two fish would have swum around until the numbfish died and they washed up on the beach.  

Porcupinefish not inflated. Porcupinefish not inflated.

Numbfish have poor eyesight and they swallow their prey whole. They often hunt for prey at night. This means they regularly make sudden, near-blind lunges at a wide variety of prey including worms, crustaceans and fish. They initially stun prey with well-developed electric organs located on each side of their body. This hunting tactic seems to work well enough…except when a porcupinefish swims by.

Porcupinefish (Diodontidae) protect themselves from predators by having sharp spines along their bodies. They also have the ability to inflate themselves by swallowing water or air. In the inflated state the spines stand out from the body.

Numbish and porcupinefish (top view) Numbish and porcupinefish (top view)

What is a numbfish?

Numbfish, also known as Coffin Rays or Electric Rays, are a species of ray, related to sharks and stingrays (Elasmobranchs).  Their body shape, including their short stumpy tail, is unique among rays. They do not have a venomous spine on their tail. Numbfish are rarely seen because they bury themselves deep in the sand with just their eyes protruding.

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