BIOLOGY 457/657
PHYSIOLOGY OF MARINE & ESTUARINE ANIMALS
March 15, 2004
BIOLUMINESCENCE
BIOLUMINESCENCE: INTRODUCTION
Outstanding and widely distributed feature of
marine animals; rare in fresh water.
“Cold light” in visible spectrum:
chemiluminescence
Most common in midwater (mesopelagic)
animals, but occurs throughout the ocean
Has a broad phyletic pattern – see the handout.
LUCIFERIN/LUCIFERASE
Luminescence involves the action of the enzyme
luciferase on the substrate luciferin.
There are many non-homologous varieties of
luciferin (see handout) and luciferase.
INTRINSIC vs BACTERIAL LUMINESCENCE
Intrinsic Organs Bacterial Organs
Widely distributed In only a few fish & squid species
May be very numerous (>1000) Usually only 1 - 2 per individual
Several types can exist together Only 1 type per individual
Usually closed off Always open to exterior (or gut)
Rarely associated with the gut Often associated with the gut
Under nervous or other control Always illuminated (may have a
shutter)
Genetically expressed Require inoculation & culture
UNITS OF LUMINESCENCE
(1) Extracellular luminescence (released)
Slimes (e.g. in polychaetes such as Chaetopterus)
“Ink” (from deep-water squids)
“Spew” (from deep-water shrimp)
“Decoys” (from ostracods)
(2) Photocytes
Bacteria (Photobacterium) reprepsent a “prokaryotic photocyte”
Dinoflagellates – Gonyaulax, Noctiluca
In many higher eukaryotes: cnidarians,
echinoderms, polychaetes, crustaceans, fishes
(3) Photophores
PHOTOPHORES
Can be highly organized and controlled light-emitting systems.
Usually present in animals with complex vision & behavior.
Often contain accessory structures: reflectors, pigments, etc
EXAMPLES OF INVERTEBRATE PHOTOPHORES
From Hastings & Morin (1991)
PHOTOPHORES OF TELEOST FISHES
BACTERIAL PHOTOPHORES IN FISHES
From Hastings & Morin (1991)
SPECTRAL FEATURES OF BIOLUMINESCENCE
SPECTRAL MAXIMA OF BIOLUMINESCENCE
MULTIPLE PHOTOPHORES:
Example 1: Aristostomias scintillans & Malacosteus niger
Data from Widder et al., 1984
MULTIPLE PHOTOPHORES:
Example 2: Abraliopsis
Data from Young & Mencher (1980)
ADAPTIVE SIGNIFICANCE OF
BIOLUMINESCENCE
The functions fall into 3 general biological categories:
(1) Predator Avoidance (the major function in the sea)
“Startle” stimulation
Predator blinding
Aposematic luminescence (prey is unpalatable or inedible)
Attracting a larger predator (“burglar-alarm” hypothesis)
Ventral counterillumination (including Abraliopsis)
Decoying or confusing a predator (lures, clouds, “blink-and-
run”; see Photoblepharon example later on)
VENTRAL COUNTERILLUMINATION
Example: Hatchetfish Argyropelecus aculeatus
Images and data from Herring (1977)
ADAPTIVE SIGNIFICANCE OF
BIOLUMINESCENCE (continued)
(2) Intraspecific Communication
Flashes, glows, and displays (e.g. Vargula – an ostracod,
Photoblepharon – a fish)
(from ImageQuest)
Seems to be involved in mate attraction, aggression, species
identification.
May be at “secret wavelengths” (Aristostomias ??)
ADAPTIVE SIGNIFICANCE OF
BIOLUMINESCENCE (continued)
(3) Prey Capture
Luminescence may be used as a lure (angler fish)
May use defensive camouflage to avoid alerting prey
Illuminate prey (Aristostomias?)
Mimic prey illumination (no known marine examples)
Stun or confuse prey
Attract prey by phototaxis (Photoblepharon?)
Photoblepharon:
“LIGHT FOR ALL REASONS”
Morin et al., 1975