Bluebottles and by-the-wind sailors, sea surface predators. Abel Tasman National Park

Korora (Little Blue Penguin) on the Abel Tasman Coastline
January 3, 2018
Cyclone Gita
Cyclone Gita in Tasman Bay, it’s ecological impact.
March 6, 2018
Show all

Bluebottles and by-the-wind sailors, sea surface predators. Abel Tasman National Park


Bluebottles and by-the-wind sailors, sea surface predators. Abel Tasman National Park

Every so often after a big onshore blow,  we get large wash ups of these beautiful creatures.  The Indo-Pacific Portugese Man o’ War or Bluebottle (Physalia utriculus) and  the by-the-wind-sailor (Vellella vellella) are the only ocean going species that occupy the  ‘pleuston’ niche (half in and half out of the water). They both start their lives in the mid-ocean ‘blue water’ and find themselves washed up on distant shores.

Portugese man o' war

Bluebottle Jelly Fish / Portugese man o’ war (Physalia utriculus), Abel Tasman National Park, Photo: Stew Robertson

Bluebottles are not classic cnidarian jelly fish,  but colonies of hydroids, known as siphonophores,  They are composed of four separate colonies of polyps and medusoids. The colony comprises a gas-filled polyp called a pneumatophore that keeps it afloat, and three other polyp types called the gastrozooids (digestive cells), gonozooids (reproductive cells) and dactylozooids (stinging tentacles).  The dactylozooids fire nematocysts (stinging cells) at zooplankton and small fish swimming below, bringing them up to the gastrozooids for consumption and distribution to the rest of the colony.  The Pacific bluebottles are distinct from the Atlantic species Physalia physalis in that they only have one long tentacle and are generally smaller.

Abel Tasman National Park

By-the-wind-sailor (Vellella vellella), washed up in the Abel Tasman National Park, New Zealand. Photo: Stew Robertson

By-the-wind-sailors (Vellella vellella) are the only species known in the Porpitidae family of Hydrozoa.  They have a similar colonial form to the Bluebottle,  however instead of a pneumatophore,  they have a rigid sail that carries them on the wind,  giving them their common name.

Both species are known to be predated on by by Purple Janthina snails and pelagic nudibranchs which also float near but not out of the waters surface.  Loggerhead turtles and ocean sunfish are also thought to feed on them.

In large numbers, these can have huge impacts on fish recruitment.  In Australia 10,000 – 30,000 bluebottle stings are reported every year, often leading to the closing of beaches.  We regularly see these in the shores of the Abel Tasman,  however,  if caution is exercised,  we don’t see many dramas.  Unlike other jellyfish,  vinegar or urine (we keep both on the boat!) is not the wisest treatment as it can aggravate the injury further.  Heat packs,  are the way to go and then the area should be treated with shaving cream and shaved with a clean razor to remove the stinging cells (might have to update the first aid kit!).  Hydrocortizone cream is also recommended.

Although we saw a lot today,  don’t worry they are a mid ocean wanderers and will be gone tomorrow once the wind swings round!

By Stew Robertson


  1. Sam says:

    Wow thanks Stewy you have shone a new light on what many would associate with annoyance and pain, but actually very well designed little floating sea creatures !

  2. selena says:

    Thanks Stew great information, pleased you keep plenty of urine on hand….lol
    You have are a wealth of knowledge! !

  3. My brother recommended I might like this website.

    He was entirely right. This post actually made my day.
    You can’t imagine just how much time I had spent for
    this information! Thanks!

  4. Vic says:

    Hey there just wanted to give you a quick heads
    up. The words in your article seem to be running off the screen in Safari.
    I’m not sure if this is a format issue or something to do with browser compatibility but I figured
    I’d post to let you know. The layout look great
    though! Hope you get the issue fixed soon. Thanks

  5. Very superb visual appeal on this website , I’d value it 10 10.

  6. I went over this web site and I believe you have a lot of wonderful info , saved to fav (:.

  7. Hmm it appears like your website ate my first comment (it was super long) so I guess I’ll
    just sum it up what I submitted and say, I’m thoroughly enjoying your blog.
    I as well am an aspiring blog blogger but I’m still new to everything.
    Do you have any helpful hints for inexperienced blog writers?
    I’d really appreciate it.

    • Stew says:

      Hi blythedarker, thanks for your comment! I’m so glad you’re enjoying it. Sorry we get a lot of spam comments, so you must have got lost in that. I’m pretty new to this to. Just write about what you’re passionate about, and in a way that your audience will understand. You’ll soon see if people want to read it. Cheers and all the best. STew

Leave a Reply

Your email address will not be published. Required fields are marked *

Share This