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Fish
bioluminescence: Distinctive flashing patterns might facilitate fish mating
Fish
bioluminescence: Distinctive flashing patterns might facilitate fish mating
Date:
March 4,
2014
Source:
American Museum of Natural History
Summary:
Scientists have shown for the first time that deep-sea
fishes that use bioluminescence for communication are diversifying into
different species faster than other glowing fishes that use light for
camouflage. The new research indicates that bioluminescence -- a phenomenon in
which animals generate visible light through a chemical reaction -- could
promote communication and mating in the open ocean, an environment with few
barriers to reproduction.
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Scientists
have shown for the first time that deep-sea fishes that use bioluminescence for
communication are diversifying into different species faster than other glowing
fishes that use light for camouflage. The new research indicates that
bioluminescence -- a phenomenon in which animals generate visible light through
a chemical reaction -- could promote communication and mating in the open
ocean, an environment with few barriers to reproduction. The study was recently
published in the journal Marine
Biology.
"Bioluminescence
is quite common in the deep sea, and many fishes inhabiting this region exhibit
complex, species-specific patterns of light-producing structures," said
John Sparks, a curator in the American Museum of Natural History's Department
of Ichthyology and one of the co-authors on the study. "But we still have
so much to learn about how these animals use bioluminescence -- for predation,
camouflage, communication, or something else. This new work provides insight
into how this phenomenon might have shaped present-day biodiversity in the deep
open ocean."
Unlike on
land, where rivers, mountain ranges, and other physical obstacles can
genetically isolate animals from one another resulting in speciation events
over time, in the deep open ocean there are few obvious physical barriers to
reproduction and gene flow. This has traditionally been considered one of the
reasons why there is a comparatively low level of fish species richness in the
deep sea. For example, bristlemouths, which are among the most abundant
vertebrates on Earth, are represented by only 21 species. But that's not the
case for all fishes. Lanternfishes, which inhabit the same mid-water, or
mesopelagic, area of the ocean, have diversified into more than 250 species.
"The
comparison of lanternfishes and bristlemouths is ideal for studying speciation
in the deep sea. Both bioluminescent groups are among the most abundant
vertebrates on Earth and live in the same dark environment," said Matthew
Davis, a research associate at the University of Kansas and the study's lead
author. "The difference in species numbers between these two groups is
striking. Both use bioluminescence for camouflage, but lanternfishes have
evolved a suite of light organs that act as a beacon for communication, which
our work suggests have had an incredible impact on their diversification in the
deep sea."
To
investigate, Sparks, Davis, and other scientists from the University of Kansas
and Johnson County Community College reconstructed a tree of life for
ray-finned fishes with a particular focus on the evolution of bioluminescence.
Many fishes
emit light from organs called photophores that appear as luminous spots on the
body. On lanternfishes, photophores are present ventrally along the belly,
laterally on the flank and head, and on the tail. The researchers discovered
that the common ancestor of lanternfishes most likely evolved this complex photophore
system during the Late Cretaceous, between 73-104 million years ago.
The
significance of the photophores on the underside of mesopelagic fishes has long
been thought to provide camouflage against predators swimming below, helping
them to blend in with any residual light shining down from the surface. But the
function of photophores on the side of the body has been obscure, until now.
Using mathematical techniques based on the anatomy of the fishes, the
researchers determined that the lateral photophore patterns on certain
lanternfish lineages are distinct enough to allow identification of individual
species. This is not the case for photophores on the belly. Recent work has
shown that lanternfishes are capable of seeing blue-green bioluminescence from up
to about 100 feet away, supporting the idea that lateral photophores could be
used for interspecific communication.
"In
this study we have shown that deep-sea fishes that exhibit unique,
species-specific bioluminescent organs, like lanternfishes and dragonfishes,
also exhibit increased rates of diversification," said Leo Smith, an
assistant curator of ichthyology at the University of Kansas and a co-author on
the paper. "This suggests to us that bioluminescent signaling may be
critical to diversification of fishes in the deep sea."
To further
test this hypothesis, the researchers plan to record lanternfish flashing
patterns using emerging technology, such as remotely operated vehicles
outfitted with ultra low-light underwater cameras. Other tools that might
assist in this type of research include the Exosuit, a next-generation,
human-piloted atmospheric diving system now on display in the American Museum
of Natural History's Irma and Paul Milstein Family Hall of Ocean Life through
March 5, 2014.
Story Source:
The above
story is based on materials provided by American Museum of Natural History. Note:
Materials may be edited for content and length.
Journal
Reference:
- Matthew P. Davis, Nancy I. Holcroft, Edward O. Wiley, John S. Sparks, W. Leo Smith. Species-specific bioluminescence facilitates speciation in the deep sea. Marine Biology, 2014; DOI: 10.1007/s00227-014-2406-x