Monday, March 7, 2011

Cockroaches of the sea

Hi Sea Fans!

Yes, believe it or not, there is something living in our oceans that is very similar to a cockroach.  Anyone scared of cockroaches?  Well, the ocean cockroaches can get bigger than 200kg!!!  How's that for scary?!
Want to know what I'm talking about?.....Nomura's jellyfish!

Photo: CORAL Magazine
These guys seem to be taking over the oceans and the possible reasons that the scientists give are:
Overfishing; Declining water quality (yucky water); and Rising sea temperatures (warmer water).

In the Sea of Japan, the numbers of these jellyfish have suddenly increased more than ever.  Since 2002, the Nomura Jellyfish population has exploded SIX times!! In 2005, as many as 20 billion jellies filled the Sea of Japan, causing losses in the fishing industry. 

Predators, like many fish and turtles, eat jellyfish, but jellyfish eat fish eggs and sometimes fish too.  So if too many fish are taken out of the sea by humans, jellyfish can take their place in the food chain and take over (Jellies and many fish eat the same thing - plankton).
Photo: CORAL Magazine
These jellies can also live in water with lowered oxygen levels, which most fish can't (fishies need to breathe!).  Increased temperatures and nutrient (food for plankton) levels cause lower oxygen levels.  Increased nutrient levels also mean increased food for the jellies.  So it looks like right now, with global warming and nutrient run-off from the land into the sea, we could be in trouble...Nomura jelly trouble.

There are several thousands of species of jellyfish, but these Nomura jellies are the ones who cause a problem - they reproduce like mad, grow fast, eat almost anything and can swim around in yucky water which most fish can't do.  This is why they are like cockroaches!

It's possible that nature will sort itself out and the jellyfish populations will become a normal size again (other jellyfish have been through this before), but we don't know so it's actually quite scary.  Let's hold thumbs that the scientists find out soon.

Have a great week Sea Fans!
Cheers
Abby
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[Info taken from an article by Richard Stone in the CORAL Magazine]
PS. Do you know that jellyfish eat Sea Monkeys? : )

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