Molecular, morphological, and biorobotic approaches to understanding evolution in the deep sea
Right off of Cape Cod, about 100 nautical miles, there is the extinct volcano chain, including Bear
Seamount, one of oldest chains in the world
Gulf Stream (warm) and Labrador Stream (cold) intersect here.
Likely that Beebe suffered from narcosis… described 6 foot long dragonfishes, but we’ve only
captured up to 2 ft.
Three major groups of deep sea fishes: stomiiforms, myctophiforms, and macrourids.
Stomiidae: 28 genera, 280 species with more described every year, lots of photophores, hyoid
barbels. Big teeth, well adapted to capturing large prey items.
Two important parameters of organisms in mesopelagic and bathypelagic: lack of light and lack of
biomass (for food). This has shaped evolution of animals living here. Lack of biomass related to
lack of light: less primary production because of absence of light.
Biomass is bimodal – due to diel vertical migration. Up at night to feed, down at day to hide.
Typical prey: myctophids.
~58230% of annual standing stock – means that these fish have to reproduce twice a year to keep
up with predation.
Often, length of prey item exceeds half the body length of the dragonfish.. Mean prey: 37.5%
One hypothesis: use “rattrapping” morphology of teeth – enormous gapes (some close to 180
degrees) – impale prey item with teeth, but the problem is getting the prey off the teeth.
This is how they deal with biomass problem: when they feed, they eat something big when
Light that penetrates water is differentially occluded. Red, purple, low wavelength blue, occluded,
so you have a bluegreen peak that penetrates water column.
So, animals use this light in different ways: blend into downwelling light
Animals also see in those same frequencies.
Deeper one goes, the more one sees a bit of a shift
One exception: loosejaw dragonfishes. They produce red light, not blue green light. Several
hypotheses: if their prey cant see red light because attuned to bluegreen, then they don’t know
they’re being illuminated. M. niger.
Called loosejaws because have no skin between man