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  1. #1
    Join Date
    Jul 2003
    Location
    West Australia
    Posts
    11,643

    Default Perhaps of interest to the biologists among us. Big brown jelly fish.

    Here in the Swan River in summer we get a huge amount of these ugly creatures. Often 20cms across and 15cm deep body. In quiet conditions you can feel the rudder hit them on my little boat. When swimming you tend to do breast stroke. Totally harmless the kids are often terrified of them. I was led to this story or research on them and found it fascinating. Takes a bit to read it all though. Turns out they give up their stinging carnivorous ways when tiny juveniles attached to rocks and about 1mm sized. They become homes to and live on algae that provide food and oxygen from sun light. Makes me quite fond of them. Ugly is beautiful. ol'will
    https://docs.google.com/presentation...&delayms=60000

  2. #2
    Join Date
    Nov 2001
    Location
    Me: Johannesburg South Africa Yacht: Richards Bay East Coast Africa
    Posts
    7,030

    Default Re: Perhaps of interest to the biologists among us. Big brown jelly fish.

    When we stayed over on Fremantle for a few days on our way to the GP in melbourne we were also amazed by the sheer quantity floating the ferry from Fremantle to Perth.

    Yes Ugly but beautiful in a strange way.

    Thls for the link
    Life is too short not to have a sea view
    Distantshaws tinyurl.com/yclt6l68

  3. #3
    Join Date
    Apr 2004
    Location
    Portchester, Solent
    Posts
    5,013

    Default Re: Perhaps of interest to the biologists among us. Big brown jelly fish.

    Small fry... https://www.bbc.co.uk/news/uk-england-cornwall-49002102

    I've seen a few over the years, biggest about 2 ft across. A few also washed up on beaches.

  4. #4
    Join Date
    Nov 2001
    Location
    Me: Johannesburg South Africa Yacht: Richards Bay East Coast Africa
    Posts
    7,030

    Default Re: Perhaps of interest to the biologists among us. Big brown jelly fish.

    When I encountered the jelly fish on the swan river It was not the size it was the quantity that intrigued me.
    Life is too short not to have a sea view
    Distantshaws tinyurl.com/yclt6l68

  5. #5
    Join Date
    Feb 2004
    Location
    Boat: Portsmouth, Us: Stewkley
    Posts
    3,012

    Default Re: Perhaps of interest to the biologists among us. Big brown jelly fish.

    Last time I did the triathlon in Tenby there were hundreds of jellyfish. The year before it had been too rough to see them. Since you can't really avoid them I just ignored them. Do UK jellyfish sting?

  6. #6
    Join Date
    Apr 2013
    Posts
    6,801

    Default Re: Perhaps of interest to the biologists among us. Big brown jelly fish.

    Thanks for the interesting link.

    On a rather different scale, I was long ago fascinated by the description and simple line drawing in Sir Alister Hardy’s The Open Sea, Its Natural History of a ubiquitous appendicularian called Oikopleura. Tadpole-shaped but just a few millmetres long, it synthesizes around itself (and discards, as often as every 4 hours) a complex but very delicate filtering ‘house’ to capture bacteria and phytoplankton. I’m sure I must have missed appendicularians in natural history TV programmes, but here is a video of a giant species and its ‘house’. https://www.youtube.com/watch?v=L1wFb_ShW7k

  7. #7
    Join Date
    Apr 2004
    Location
    Portchester, Solent
    Posts
    5,013

    Default Re: Perhaps of interest to the biologists among us. Big brown jelly fish.

    Quote Originally Posted by Rogershaw View Post
    When I encountered the jelly fish on the swan river It was not the size it was the quantity that intrigued me.
    I remember many years ago seeing a similar phenomenon in the Beaulieu River (Hampshire UK). The water was more like Moon Jellyfish soup. These were small 3 - 4 cm. I did try to research how it was possible for, presumably, a swarm of adults to navigate up the river in order to reproduce and create this swarm of young going the other way. Never did find a convincing explanation.
    Has anyone seen this in the Beaulieu river in recent years or was it a one-off?

  8. #8
    Join Date
    Apr 2013
    Posts
    6,801

    Default Re: Perhaps of interest to the biologists among us. Big brown jelly fish.

    I recall that when sampling the front to the south of the IoM in the mid ‘70s, we knew how well-defined it was only from our physico-chemical monitors. So it was startling to have it suddenly manifest in the davit floodlight at dead of night, by the sudden appearance of a mass of jellyfish (and attendant garfish) with a leading edge as sharp as guardsmen on parade. There has since been quite a bit of research on jellyfish aggregation at discontinuities, and both physical movement by the water and/or wind, and active swimming, may be involved.

  9. #9
    Join Date
    Sep 2013
    Location
    Solent
    Posts
    366

    Default Re: Perhaps of interest to the biologists among us. Big brown jelly fish.

    Quote Originally Posted by Hydrozoan View Post
    ... a mass of jellyfish (and attendant garfish) ...
    Do they go around together?

  10. #10
    Join Date
    Feb 2007
    Location
    Essex
    Posts
    22,659

    Default Re: Perhaps of interest to the biologists among us. Big brown jelly fish.

    What we'll all be eating when the seas have been fished out.
    Far away is near at hand in images of elsewhere

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