Deep Sea Habitats

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Deep Sea Habitats
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Factors Driving Deep Sea Systems

• High pressure (1 atm/33 ft)
• Low temperature (4?C)
• Depth
• Lack of sunlight
• Lack of photosynthesis
• Scarcity of food resources
• Enormous volume of water further reduces
  encounter probability (mates, prey)

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Deep Sea biota

• 75 of sea floor is below 3000 m depth
• Imported nutrients from photic zone
• Seasonal pulses of organic matter
• Seafloor communities low biomass but surprisingly
  high biodiversity
• Most benthic organisms in the deep sea
  (polychaetes, arthropods, molluscs, echinoderms)
  survive on detritus in sediment
• Low biomass but high diversity of fish species
  (why?) scavengers and predators

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Factors Driving Hydrothermal Vent Systems

• High pressure
• Low temperature
• Depth
• Lack of sunlight
• Lack of photosynthesis
• Scarcity of food resources
• Enormous volume of water further reduces
  encounter probability
• Counteracted by
• Chemosynthetic bacteria (primary producers)
• Hot, mineral-rich water
• Location advantages and disadvantages

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Succession in Hydrothermal Vents

• New vent forms at diverging plates
• Chemosynthetic bacteria
• Amphipods, copepods
• Grazers/filter feeders limpets, clams, mussels
• Scavengers vent crabs, worms, fish
• Predators vent crabs, octopi
• Symbiotic with primary producers (bacteria)
  vestimentiferan worms, giant clams
• 1. Tevnia jerichonana
• 2. Riftia pachyptilia
• Longevity of vent itself estimated at years to
  decades

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Bioluminescence

• Luciferin Luciferase O2 -gt
• Oxyluciferin light
• or
• Photoprotein Ca2 -gt light

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Bioluminescence
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Deep Sea and Midwater Creatures

• Reportedly brought to surface or washed ashore
  in Phuket following the earthquake and tsunami of
  26 Dec. 2004.
• Origin and authorship of photos unknown these
  were circulated via email with no references
  given. Captions are taken from titles of images.

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Aphyonous
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Basketwork eel
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Black dragonfish
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Blind lobster
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Blob fish
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Carrier shell
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Chimaera fish
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Chimaera pup
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Coffinfish
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Crab
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Fangtooth
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Firefly squid
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Gunard
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Hatchetfish
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Lizard fish
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Oreo dory
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Prickly shark
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Sea spider
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Shovel nosed lobster
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Stargazer
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Stone crab
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Swimmer crab
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Tongue sole
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Umbrella mouth gulper eel
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Viperfish
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General Characteristics of the Mesopelagic

• Located from just below the photic zone to point
  of total darkness
• All food must come from above
• All oxygen must come from above
• Oxygen supply replenished by the great ocean
  conveyer
• Main thermocline appears here

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Zooplankton of the Mesopelagic

• Essentially the same major groups occur here as
  in epipelagic
• Copepods krill are dominant, shrimp also common
  
• Many krill shrimp have photophores for
  bioluminescence
• Ostracods also abundant at times, appear like
  clams but are crustaceans
• Chaetognaths important predator, abundant at
  times
• Squids also occur and have photophores
• A few octopuses also

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Fishes of the Mesopelagic

• Most are small (lt 10 cm)
• Bristlemouths lanternfishes most abundant
• Bristlemouths have rows of photophores on ventral
  surface
• Lanternfishes have rows of photophores on their
  heads elsewhere
• Many of the other fishes are eel-like in shape
  with rows of photophores along their ventral
  surfaces

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Adaptations of Mesopelagic Organisms

• General Feeding Adaptations
• Only 20 of the food from the epipelagic reaches
  the mesopelagic
• Small size is a primary adaptation for fishes
  because of lack of food
• Many fish have large mouths, some that can
  unhinge
• Can eat most anything, even prey larger than
  themselves in some

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Migrating Fish vs. Non-migrating Fish
Migrators Non-migrators
Swim bladder Strong muscles Well developed bones Generally smaller Large eyes mouth Photophores No swim bladder Flabby muscles Weak bones Generally a little larger Large eyes mouth Photophores
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The Deep Scattering layer (DSL)

• Sonar shows a shadowy region 300-500 m below the
  surface
• DSL moves to surface at night
• DSL depth directly related to light levels
• Caused by the mass of migrating organisms
• Echo in sonar is primarily from sound waves
  bouncing off swim bladders of fish
• Move to surface to feed at night, return to
  depths during day to rest hide

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Sense Organs

• Fish, squids, shrimps, etc. have larger more
  sensitive eyes
• Some have tubular eyes
• Some fish with tubular eyes have yellow filters
  that help them distinguish ambient light from
  bioluminescence
• many fish have well developed lateral lines, and
  eel-like shapes of some make the lateral line
  even more sensitive

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Camouflage

• Countershading transparency are used in the
  upper mesopelagic
• Silvery sides (from guanine crystals) laterally
  compressed shape are used in some
• In the deeper parts of the mesopelagic organisms
  tend to be orange, red, purple or black

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Bioluminescence

• Counterillumination can hide a fish against light
  from above
• Color of bioluminescence is matched to ambient
  light (blue-green)
• Many, like shrimp, can match the brightness of
  the background light
• Photophores may produce light on their own or
  because they contain bacteria.
• Light is produced chemically using luciferin and
  luciferase
• Some produce bioluminescence without photophores
• Some release bioluminescent fluids or "inks"
• Bioluminescence may be used in mating, to confuse
  a predator, or to lure prey

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Adaptations to the Oxygen Minimum Layer

• Oxygen utilized by detrital food chain
• Relative abundance of food results in very low
  oxygen levels remaining
• Even less food is available below the oxygen
  minimum layer, so more oxygen remains
• Organisms have better gills, are more sedentary,
  more efficient hemoglobin

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Zonation in the Deep Ocean

• Bathypelagic - 1,000-4,000 m
• Abyssopelagic - 4,000-6,000 m
• Hadopelagic - below 6,000 m (to 11,000 m)

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General Adaptations of Deep Ocean Organisms

• Countershading completely absent
• Colors generally drab gray or off-white, fish
  often black, shrimp red
• Bioluminescence widespread, but fewer
  photophores, mostly on head and sides
• Bioluminescence probably used for attracting prey
  or mates
• If eyes are present, then generally very small
• Abiotic factors fairly constant pressure high,
  temperature just above freezing, chemical
  properties constant

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The Problem of Food

• 5 of food produced in photic zone reaches here
• Deep sea fishes (most common are bristlemouths
  and anglerfish) are well adapted to low food
• Some are gulpers swallowers

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Sexual Reproduction

• Many of the fishes are hermaphroditic
• Photophores may be used to advertise for a mate
• Pheromones also used in some cases
• Male anglerfish attach to females using their
  jaws

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The Effect of High Pressure

• Can be as high as 1,000 atmospheres in deepest
  trenches
• Many fish have no swim bladders
• Lower limit for fish is about 8,400 m

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The Deep Ocean Floor

• Feeding in the Benthos
• Fastest sinking material reaches bottom
• Chitin is broken down by bacteria to usable
  material for others
• Meiofauna abundant and eat bacteria DOM
• Suspension feeders essentially absent, most are
  deposit feeders
• Predators are rare, but include crabs, sea stars,
  brittle stars, Pycnogonida, etc.
• Some of the invertebrates display deep-sea
  gigantism
• Dead bodies are an important food source too,
  especially to amphipods, some of whom are
  specialized as scavengers
• In shallower areas fish may congregate at dead
  bodies

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General Life Traits in Deep Sea

• Organisms grow more slowly and live longer
• Produce large eggs with a lot of yolk
• Produce few eggs, often times with feeding

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Summary

• Adaptations to deep sea life
• Special physical and chemical properties
• Dark
• Scarce food
• Unique environment