Biology

Corella eumyota is a brooding hermaphroditic sea squirt.

It is capable of self-fertilization because the location of the sperm duct opening is very close to the oviductal opening.

The non-feeding tadpole-shaped larvae are retained after hatching until they are competent to settle, resulting in:

  • an extremely short free-swimming larval period
  • limited dispersal
  • a tendency for the larvae to settle on the parent tunic or adjacent adults immediately after release, resulting in the formation of large clumps of variously sized individuals

Corella eumyota is a summer brooder.

In the southern hemisphere the breeding season may last more than six months of the year; from mid-September to the end of March. In the northern hemisphere its breeding season is offset to correspond to the longer day length and warmer temperature.

Dispersal

Adult orange-tipped sea squirts self-fertilise, brood their young, and the larvae have an unusually short free-swimming period. So, the transfer of even one or a few individuals on fouled boat hulls might be enough to establish new populations.

Its broad distribution in western Europe indicates that Corella eumyota is likely to spread rapidly within a region once established.

The mode of transport of Corella eumyota into the northern hemisphere, while unknown, is presumed to be anthropogenically by:

  • hull fouling
  • transport of settled post-metamorphic individuals on floating debris in ballast water, or
  • importation of contaminated mussels or oysters from the southern hemisphere
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