Corella eumyota (orange-tipped sea squirt)

The orange-tipped sea squirt is an invasive species that has spread itself around the world.

It is highly successful and can establish a new population from only a few individuals, possibly even one.

It attaches to almost anything that is covered in seawater, including ship hulls and piers, and even grows on other organisms. It can adapt its shape to fit any available space.

Corella eumyota poses a threat to biodiversity and aquaculture.

Species detail

Corella eumyota often form communities on floating pontoons

Floating pontoons are often Corella eumyota's preferred settlement substrate. © R Huys

Corella eumyota is an invasive solitary sea squirt.

It belongs to the Tunicata, a marine group of underwater saclike filter feeders with inhalant and exhalant siphons.

  • it often forms large clumps of tightly packed aggregations on floating pontoons, piers, ropes, ship hulls, and other submerged structures
  • individuals can be so tightly adherent to one another that it is usually not possible to separate them without tearing the external covering (tunic)
  • this species can grow over other organisms, including other invasive species
  • Seven orange-tipped sea squirts on a dead Pacific oyster
    Taxonomy

    Find out more about this sea squirt’s shape, and how it moulds itself to fill the available space.

  • Sea squirt community attached to a rope
    Distribution

    Discover where you're likely to find Corella eumyota.

  • Corella eumyota dominates a newly submerged concrete pontoon in Portugal
    Biology

    Although the orange-tipped sea squirt has limited means of dispersal, it has found its way to virtually every continent on Earth. But how?

  • Corella eumyota can use any substrate, including other sea squirts
    Conservation

    Sea squirts are an invasive species that are easily spread around the world and pose a serious threat to biodiversity and commercial aquaculture. Find out more.

  • Corella eumyota are capable of using any substrate, including other sea squirts
    References

    Get more information on Corella eumyota.

Images

Dense aggregations of Corella eumyota in Dorset

Corella eumyota forming dense aggregations in a marina in Weymouth, Dorset.

© JDD Bishop
Floating pontoons are preferred settlement sites for new arrivals

Floating pontoons - made of ropes, tyres, buoys etc. - are often the preferred settlement sites for new arrivals, and have become the primary focus for rapid assessment surveys for alien species.

© R Huys
Ropes are an ideal substrate for colonising sea squirts

Ropes are an ideal substrate for Corella eumyota and other sea squirts to colonise.

© R Huys
Seven orange-tipped sea squirts on a dead Pacific oyster

Seven individuals of the orange-tipped sea squirt on a dead Pacific oyster (Crassostrea gigas – another non-native species) in Noss Mayo, Devon. Note the typical orange coloration of the siphons and the black U-shaped hind-gut.

© JDD Bishop
Extreme clumping behaviour of sea squirt can block pipes and obstruct installations

The extreme clumping behaviour (settlement on conspecifics and moulding into the shape of the existing surface) could turn Corella eumyota into a nuisance, blocking pipes or obstructing installations.
[scale in cm]

© JDD Bishop
Corella eumyota dominates a newly submerged concrete pontoon in Portugal

Corella eumyota has the capacity to establish dense populations very rapidly. Here it dominates the submerged surface of a concrete pontoon, forming an almost continuous carpet in Vila Praia de Âncora, Portugal. The marina was built only two years before the survey.

© A El Nagar
Corella eumyota are capable of using any substrate, including other sea squirts

Space availability is the prime factor in the establishment of a non-native species. When space is limited Corella eumyota is capable of using any substrate, including other sea squirts such as Ascidiella aspersa. Note the two young individuals in the middle.
Boulogne-sur-Mer, France.

© R Huys
Corella eumyota uses other non-native species as substrate

Corella eumyota even uses other non-native species as substrate such as the leathery sea squirt Styela clava. It is assumed to have been transported on the hulls of warships following the end of the Korean War in 1951, and first introduced at Plymouth.

© R Huys
About the author
Dr Rony Huys
Prof Rony Huys

Researcher in the Crustacea Group, focusing on the evolutionary biology of free-living and symbiotic copepods.

Department of Zoology
Zoology Crustacea Research Group

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