Styela

A Vulnerable genera from the “Other: Chordata” group, mostly found in Cobbles

Cobbles

Vulnerable

Other: Chordata

Genera Characteristics Recorded Traits Possible Values
Size in cm
  • 1-10 cm
  • 11-20 cm
  • <1 cm
  • 1-10 cm
  • 11-20 cm
  • >20 cm
Genera Characteristics Recorded Traits Possible Values
Motility (Adult)
  • Sedentary
  • Adult
  • Short Range Mobility
  • Sedentary

“Sedentary”

Motility (Larval)
  • Short Term Planktonic
  • Long Term Planktonic
  • Short Term Planktonic
  • Brooded or Laid Eggs

“Short Term Planktonic”

Lifespan
  • 1-2 years
  • >10 years
  • 3-10 years
  • 1-2 years
  • <1 year
Maturity
  • <1 year
  • >4 years
  • 3-4 years
  • 1-2 years
  • <1 year
Fecundity
  • 10000 - 1 million
  • 1 - 10
  • 10 - 100
  • 100 - 1000
  • 1000 - 10000
  • 10000 - 1 million
  • > 1 million

Image: Styela © John Ryland

Vulnerability

Styela is a large ascidian (Sea squirt) belonging to the Family Styelidae. It reaches a height of up to 12cm & is attached to substrata of rocks & boulders on the seabed where it feeds by filtering particulate matter from the water column. It is vulnerable to dredging & to deposition of sediment mobilised by the dredging process.
 

Recoverability

Styela has a life-span of 1-2yrs & reaches reproductive maturity in <1yr. The genus is hermaphrodite & has an annual episodic breeding phase from April to November as which as many as 20,000 eggs of about 0.15mm are released & fertilised externally in the water column. The lecithotrophic larvae stage is very short, lasting <1 day & is followed by settlement close to the site of spawning. Although this genus has a high fecundity, dispersal potential is estimated to be <100m. It is unlikely that the seabed would be colonised rapidly from outside the area following disturbance. The genus has a low recoverability.

 

References

  • Biology

    • Millar, 1970
  • Taxonomy

    • Millar, 1970
  • Distribution

    • Hayward & Ryland, 1990
  • Reproduction

    • Berrill, 1929
    • Millar, 1970