Thursday, 26 February 2015

Day 117 - Becalmed Barnacles

Hey everyone,

Whitby Abbey high up on the cliffs
Day 117 today and I thought I'd do a little bit more on my visit to the coast at Whitby and the rock pools. Before I do though Dad told me an interesting fact about Whitby.

Whitby has an Abbey which sits high up on the cliffs, there's a great walk up 199 steps to get to it which we've scampered up and down lots of times. But there have been buildings there at the top for a long time and in 664 St Hilda held a meeting there called a Synod where it was decided how the date of Easter should be worked out!

There's another cool story that starts in Whitby called Dracula too. More on that another day.

Anyway. back to Barnacles. What did I find out about these creatures. Well like Limpets there's more to them thank you might think.

  • The first surprising thing I found out is that they are not molluscs, which you might think they are because of their shells when you see them on rocks, they are in fact a crustacean and are related to crabs and lobsters.
  • There are over 1000 species of barnacle some of which can live over 20 years...
    Acorn Barnacles (Semibalanus balanoides)
  • ...Which means, because their average clutch size is 1,000, that one barnacle can potentially produce 20,000 young!

  • Barnacles are hermaphrodites, so can make male and female reproductive cells, but they are usually fertilised by another barnacle rather than self fertilised.
  • Once fertilised a barnacles egg turns into a larvae called a nauplius. This swims about, usually with planton as it is soo small,and feeds They go through 6 stages before the turn into a cypris larvae. This doesn't feed but finds a place to settle before turning into the adult barnacle.
    Barnacle hitching a ride on a Limpet
  • Barnacles will grow on lots of things, rocks, ships and animals like turtles or whales and even limpets (see right).
  • They are mostly harmless to animals if they do grow on them.
  • A barnacle shell is made up of plates, usually 6,  plus two moveable plates which they use to protect themselves when not feeding.
  • Barnacles feed on mainly plankton which they collect by straining them out of the water with feathery like legs that they extend from their shells. 
  • They do have predators, but mainly at their larval stage, which include worms, snails, starfish etc.
  • Charles Darwin studied barnacles for 10 years - he must have been fascinated by them
  • Scientists are very interested in how barnacles attach themselves to rocks. They have a very firm grip and this is being investigated to make glues that work well on wet surfaces where most glues don't work.
So, I hope you found that interesting. Here's some links in case you want to find out more.

Hope you enjoyed,


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