Characteristics of bioluminescence were examined in
zooplankton and marine snow. Over 100 species of
cnidaria, ctenophores and other plankton were
collected on blue-water dives, from submersibles and
deep-sea trawls. Their bioluminescense spectra were
measured, with wavelengths ranging from 440 nm to
506 nm, with different species of medusae covering the
entire range, and ctenophores centered more narrowly
around a mean of 486 nm. Contrary to prior belief, two
species of ctenophores, Pleurobrachia and
Hormiphora were found to be non-luminous, and this
was demonstrated through chemical and physical
assays. Also against previous views, luminescence
was discovered in a species of deep-sea chaetognath.
This was the first phylum discovered to be
bioluminescent in more than 50 years. Assays
indicated that the chemical basis of this light production
was coelenterazine, the same substrate used by at
least 6 other phyla. The bioluminescent properties of
marine aggregates were also investigated. These
aggregates were overwhelmingly bioluminescent, with
over 98% producing light, and between 1% and 44% of
the light produced in the water arising from particles.
Marine snow had luminescence which was 200 to
20,000 times higher than an equivalent volume of
seawater, implying that luminescent organisms
associated with aggregates are not perceived alone,
but rather as concentrated masses.