Day 8 of Life Beneath the Keel

On Sunday 13 September, at 1800 BST, The Island Trust is live streamingLife Beneath the Keel’ from Plymouth Yacht Haven as part of the Ocean Institute’s virtual Maritime Festival. This is the eighth in a series of blogs about the marine life we hope to discover then.

Day 8:  7 September 2020 | Bryozoans

Bryozoans are colonial animals often mistaken for other things. They take many different forms. What they have in common is that they are consist of a colony of individual animals, zooids, which are all clones. They shelter in a structure made of chitin, and feed using a lopophore, a ring of tentacles surrounding the mouth (yet another shuttlecock!)

  1. Sea mats  look like a fungus. They are eaten by seaslugs (and other things).
  2. In image 2 you can see the lophophores emerging to feed, held up by hydrostatic pressure and able to be withdrawn very quickly when threatened. You can tell they’re a more complex life form – they do have bottoms.
  3. Some look like hydroids, which we saw on 2 September in the Cnidarians blog. It’s no wonder the Seasearch guides cover both groups in one volume.
  4. They eat plankton, dead stuff and poo, and probably micro-plastic if it’s small enough.
  5. Some look like worms.
  6. Some, which we are unlikely to find growing on pontoons, look like seaweeds, and even have a common name, Hornwrack, which makes them sound like one.
    And there are yet more forms!
  7. Not all the bryozans we find are natives. Watersipora subatra can be encrusting, like the one in picture, or erect and leaf-like. It has been recorded in the Channel Islands, along the South Coast of England, West Wales and Northern Ireland. There is still an international debate on what species is found where; ours may have come from the Gulf of Mexico.

John Hepburn, Ocean Discoverability Project Manager
7 September 2020