25 April 2012

Exploring Marine Creatures I: Velella

Assalamualaikum... :)
Velella velella (Va-le-lia) 
  • Mobile hydroids that normally travel at the surface with the aid of buoyant float tissue.
  • Propelled by winds that act on a rigid triangular sail held above the float, inhabit open ocean waters.
  • The sail is made of a chitinous material and has a distinctive cellophane-like texture.
  • Individuals with two types of sails that are mirror images of each other exist in a population - pushed in opposite directions by the wind.
  • The float and surrounding tissues are endowed with an attractive deep blue pigment.  
  • The float contains a series of sealed air chambers that provide buoyancy.  
  • Total width of the floating polyp is usually less than 6 cm.  
  • Beneath the float is a grouping of several types of zooids, colored brown by the presence of zooxanthellae.  
  • A large central mouth is surrounded by shorter reproductive stalks with mouth openings that bud tiny adult medusae that produce eggs and sperm.  
  • Multitudes of tiny brownish-green medusae that never grow to more than 3 mm tall are cast off.
  • These then release the eggs and sperm that produce free-swimming larvae which eventually develop into more floating polyps. 
  • It's not known if a planula larva is produced initially, but during the early stages oil droplets are formed that bring the young Velella to the surface.  
  • Dangling beneath the rim of the float are hollow tentacles that ensnare fish and invertebrate eggs, copepods and appendicularians.  
  • Velella is found in warm and temperate seas throughout the world.  
  • Although not dangerous to people, it's best not to handle them or touch your face or eyes if you've been touching beached individuals since some irritation may result.  
(^,^)

6 comments:

kura said...

velella velella. nama dia cantik :0

haslinda said...

@kura: secantik velella tu jugak... :)

pjolinda said...

eemmmm...xtau nak komen pe...heee~

haslinda said...

@pjolinda: x tau nak komen??? err, tp tu kan da komen. ish... hehe :)

Liza Adi said...

bahaya tak benda ni....

haslinda said...

@Liza Adi: tak bahaya macam sgth2 jelly fish. tp kalo terkena ngan binatang ni, still ada effect mcm gatal2 gitu...