Monday, 29 October 2012

Weird and Wonderful Halloween Special Part 1: Ghosts of the Deep

Ione Bingley

Dive with me to the underworld, 3000m below the bone-chilling Antarctic Ocean, it is pitch black, and the water is below 5°C. The icy gloom is broken by a rippling nimbus of light gliding towards you, a seeming ghoulish globe of otherworldly ectoplasm. This, my friend, is just one of the many ghostly forms that the members of the Ctenophore phylum take, also known as ‘comb jellies’. They skulk in the corners of every inhospitable deep sea, stalking their unfortunate prey. The comb jelly may look like a divine messenger, but is, in fact, one of the most sinister, voracious, and destructive of the planktonic organisms.

Although these trippy Ctenophores may look like jellyfish, do not be fooled, they lack toxins and cnidocytes (explosive cells containing toxin), their weapon of choice is the colloblast. The epidermis of the Ctenophore tentacles are covered with these colloblasts, containing a super-sticky adhesive held in granules, poised for rupture on contact with their prey. Their ill-fated planktonic victims become irredeemably entangled only to be unmercifully digested with a wipe of the trapping tentacle across their captor’s mouth.

Along the bilaterally symmetrical blob of the Ctenophore are 8 evenly spaced rows of ciliary combs, covered by thousands of cilia (little hairs) which propel the glittering ghoul, making it the largest organism to move in this way. The ghostly glow of the Ctenophore comes from the production of biochemical light from canals under the comb rows and the rippling cilia produce the glimmering effect. The bioluminescent flashes are brighter than in any other organism and the colour changes with temperature… Cterrifying stuff!