Oceans 11 – Dalesandro
Assignment #11 – Deep Sea Eyes
Value: 10 points
Instuctions: Read the attached article and answer the questions in full sentences.
1) a) What kind of fish was studied according to the article?
b) Where does this fish live?
2) How many different fish were examined? What did Dr. de Busserolles notice when her team
examined the fish?
3) What connection did Dr. de Busserolles suspect she would find during the examination of
the fish?
4) What did the study actually find? Why was this “contrary to their expectations”?
5) What is the next step in this research, according to Dr. de Busserolles?
6) List one possible explanation for her findings that Dr. de Busserolles thinks she might be
able to confirm in the future.
7) What other visual parameter does she intend to investigate?
8) Look at the picture of the two lanternfish at the end of the article. What do you notice? Can
you come up with any possible explanations for the differences in the fish? [3 pts.]
Evolution Trumps Ecology In Deep-Sea Fish Eyes
From ScienceNet Australia, Sunday, April 14, 2013.
An investigation by University of Western Australia scientists into factors which affect eye size in
lanternfish, a deep-sea species, has found that eye size varies based on the individual fish’s evolutionary
status, rather than ecological pressures.
The study found there was great diversity in eye size among lanternfish at all taxonomic levels including
the subfamily, tribes, and genus.
Researchers at the UWA Oceans Institute studied how types of lanternfish (Myctophidae) have visually
adapted to navigating the ocean’s mesopelagic zone (200m-1000m) where sunlight diminishes
exponentially with depth.
The mesopelagic region or Twilight Zone has the greatest density of bioluminescent emissions, or light
emitted by the animals themselves, which they use to interact with prey and predators.
They examined 237 members of the lanternfish family spanning 61 different species, with eye and lens
diameters ranging from 0.6 mm to 11.0 mm, and were collected from research cruises in different parts
of the world including in the Coral Sea.
UWA researcher Dr. Fannie de Busserolles says while in the field she had noticed significant differences
in eye size compared to body size between different lanternfish species and wanted to investigate the
difference.
“Knowing that a larger eye will be more sensitive we thought there might be a connection between the
amount of light present in the environment and the relative eye size of a species,” she says.
“We hypothesised that species with a deeper distribution in the mesopelagic zone and/or a reduction of
bioluminescent emissions will have smaller eyes, and that ecological factors rather than the evolutionary
history of the family will drive the evolution of their visual system.”
The study found there was great diversity in eye size among lanternfish at all taxonomic levels including
the subfamily, tribes and genus.
But contrary to their expectations the team did not find a link between the eye size and the
depth/luminous tissue patterns on the fish identified.
“A strong phylogenetic signal was observed for the eye size variable suggesting that this characteristic
may be mainly influenced by the evolutionary history of the family instead of the ecological factors as
we expected,” de Busserolles says.
She says the next step will involve closely examining the visual system of different species of lanternfish
as eye size is only one parameter involved in assessing a species’ visual capabilities.
“It is possible that small eyes possess other visual adaptations that will enhance the sensitivity of the eye
and potentially make them as efficient as larger eyes,” de Busserolles says.
“We will then look at several other visual parameters, especially the photoreceptors in the lanternfish’s
retina, to test these new ideas.”
Difference in eye size compared to body size in two species of lanternfish.