| 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 over-whelmingly 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. |
