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Northern Rock Barnacle - Semibalanus balanoides This is the crowded form of the northern rock barnacle. When crowded, they take a columnar or twisted shape that can be up to 25 mm long. You can see a bunch of little things attached to this barnacle - mussels and smaller barnacles.<br /> <br /> *Note: This barnacle was dead. I wouldn&#039;t have uprooted it otherwise.<br /> <br /> Habitat: Crowded colony in the intertidal<br /> <figure class="photo"><a href="https://www.jungledragon.com/image/89869/northern_rock_barnacle_-_semibalanus_balanoides.html" title="Northern Rock Barnacle - Semibalanus balanoides"><img src="https://s3.amazonaws.com/media.jungledragon.com/images/3232/89869_thumb.jpg?AWSAccessKeyId=05GMT0V3GWVNE7GGM1R2&Expires=1683763210&Signature=Mw8oxQ39f5TE26mziDv6J3E87jM%3D" width="200" height="156" alt="Northern Rock Barnacle - Semibalanus balanoides This is the crowded form of the northern rock barnacle. When crowded, they take a columnar or twisted shape that can be up to 25 mm long. You can see a bunch of little things attached to this barnacle - mussels, a periwinkle, and smaller barnacles.<br /> <br /> *Note: This barnacle was dead. I wouldn&#039;t have uprooted it otherwise.<br /> <br /> Habitat: Crowded colony in the intertidal<br /> https://www.jungledragon.com/image/89868/northern_rock_barnacle_-_semibalanus_balanoides.html Geotagged,Semibalanus balanoides,Spring,United States" /></a></figure> Geotagged,Semibalanus balanoides,Spring,United States,barnacle Click/tap to enlarge

Northern Rock Barnacle - Semibalanus balanoides

This is the crowded form of the northern rock barnacle. When crowded, they take a columnar or twisted shape that can be up to 25 mm long. You can see a bunch of little things attached to this barnacle - mussels and smaller barnacles.

*Note: This barnacle was dead. I wouldn't have uprooted it otherwise.

Habitat: Crowded colony in the intertidal

Northern Rock Barnacle - Semibalanus balanoides This is the crowded form of the northern rock barnacle. When crowded, they take a columnar or twisted shape that can be up to 25 mm long. You can see a bunch of little things attached to this barnacle - mussels, a periwinkle, and smaller barnacles.<br /> <br /> *Note: This barnacle was dead. I wouldn't have uprooted it otherwise.<br /> <br /> Habitat: Crowded colony in the intertidal<br /> https://www.jungledragon.com/image/89868/northern_rock_barnacle_-_semibalanus_balanoides.html Geotagged,Semibalanus balanoides,Spring,United States

    comments (5)

  1. View Ferdy Christant's profile
    Ferdy Christant
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    Can you explain this concept of a crowded form? I don't understand what it means? Posted 3 years ago
    1. View Christine Young's profile
      Christine Young
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      Sure...Barnacles are sessile as adults, meaning they can't move or relocate if the area where they live is crowded. Usually, when not overcrowded, barnacles grow to look like this (like a low volcano):

      Northern Rock Barnacle - Semibalanus balanoides Common, intertidal barnacles that resemble volcanoes. They have a membranous base and the outer shell consists of white, overlapping, shell-like plates that grow with the animal.<br /> <br /> Habitat: Covering rocks in the intertidal zone. Geotagged,Semibalanus balanoides,Summer,United States,barnacle,barnacles

      Their morphology/shape changes when they are overcrowded and they form "hummocks" of tall, densely packed individuals. So, when space is limited and the larvae have to settle in a crowded area, they grow tall and take a column-shape (like a long tooth). The taller they grow, the more likely it is that they will be able to outcompete their neighbors and be the first to filter food particles out of the water because they are more elevated from the substrate. The shorter barnacles are stuck with the leftovers. So, being a tall barnacle is a huge benefit in a crowded space.

      But, overcrowding can increase mortality rates as well as they are really tightly packed together and competition for food is tough. However, there are some benefits to crowding. Crowded barnacles rely on support from their neighbors and thus use less resources to build their shells strong. Instead, they can pump energy into increasing their body tissues. Also, they get protection from dessication when crowded, and it's easier to reproduce. So, as long as they can get enough food, crowding isn't that bad for a barnacle.

      Here's an image (of a different species) to show the difference between a normal individual and a crowded/hummocked individual:
      https://www.researchgate.net/profile/Boris_Lopez2/publication/236013058/figure/fig1/AS:562677518790656@1511164182487/Austromegabalanus-psittacus-specimens-with-different-base-morphologies-subject-to.png       Posted 3 years ago, modified 3 years ago
      1. View Christine Young's profile
        Christine Young
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        Another photo of crowded barnacles:
        https://inverts.wallawalla.edu/Arthropoda/Crustacea/Maxillopoda/Cirripedia/Balanus_glandulaHighrise1DLC2005.jpg         Posted 3 years ago
        1. View Ferdy Christant's profile
          Ferdy Christant
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          Fantastic information, totally get it now. I've internalized it as humans building houses, when it gets too crowded, the skyscrapers come. The unique thing of course is that in this case it concerns a living organism, crazy. Posted 3 years ago
          1. View Christine Young's profile
            Christine Young
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            Exactly...Skyscraper barnacles ;). Posted 3 years ago

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The Northern Rock Barnacle

''Semibalanus balanoides'' is a common and widespread boreo-arctic species of acorn barnacle. It is common on rocks and other substrates in the intertidal zone of north-western Europe and both coasts of North America.

Info 14 1
Similar species: Symmetrical Sessile Barnacles
Species identified by Christine Young
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By Christine Young

All rights reserved
Uploaded Feb 13, 2020. Captured Jun 18, 2019 08:11 in 1563 Post Rd, Wells, ME 04090, USA.
country flag of United States of America Explore United States of America 34,978 8,647 8
  • Canon EOS 80D
  • f/6.3
  • 1/664s
  • ISO100
  • 100mm