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Egg Wrack

Adam Harmer (April)

You can't fail to come across Egg Wrack (also known as Knotted Wrack) on the coastal waters of North Wales.
Growing up to 2 metres or more in length, you can recognise Egg Wrack by the single, large air bladder in the centre of the fronds which allows it to float upward towards the sun for maximum benefit from the light during photosynthesis.
Along the edge of the fronds you'll also find "lollipops" - stalked receptacles containing the reproductive organs which can be seen in varying states of development. These lollipops turn yellow when they are ripe.

The abundance of Knotted or Egg Wrack in the mid-tidal area is due to several factors that help it win in the struggle against competitors. It has the capability to survive low temperatures and has a high breaking strain. More importantly, it lives for around 15 years whilst other seaweeds barely reach 3 years old before they die off. This means it has time to create a blanket over the rocks, preventing colonisation by new competitors and denying anything below it access to valuable sunlight. I've never heard of anything that eats seaweed either so Egg Wrack doesn't even have that threat to halt its journey towards coastal domination.

Interestingly each frond produces only one air bladder per year of its life so you should be able to estimate the age of an Egg Wrack plant next time you come across one.

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