1. Deep Sea Environment
2. Overview of Deep Sea Food Webs
3. Deep Sea Plankton
4. Deep Sea Nekton
5. Deep Sea Benthos
6. Hydrothermal Vent Communities

Deep Sea Zone

1. Also called the Bathypelagic and Abyssopelagic zones
2. Below 1,000 meters
3. Aphotic
4. Temperature 3 to 4 ^{degrees centigrade}
5. Salinity 33 ppt
6. Dissolved oxygen concentration rises to near maximum
7. High Pressure (100 to over 1,000 atm)
8. Nitrogen and phosphorus concentrations stabilize (Nitrate=1.5 ppm Phosphate=0.6 ppm)

Deep Sea Food Webs

1. Detritus based food webs
2. Sit and wait scavenging and carnivorous nekton
3. About 5 percent of food produced in the epipelagic zone reaches the deep-sea zone
4. Nekton of deep sea fishes
5. Deep sea bristlemouths and anglerfish are important

Deep Sea Bacteria Plankton

1. Less abundant than in the mesopelagic
2. Little detritus to decompose

Adaptations of Deep Sea Bacteria Plankton

1. Adapted to use nutrients in very low concentrations
2. Adapted to function under extreme pressure
3. Can take up to 1,000 times longer to decompose organic matter than shallow-water bacteria

Deep Sea Zooplankton

1. Copepods, krill, and arrow worms are less abundant
2. A variety of shrimps are relatively common

Adaptations of Deep Sea Zooplankton

1. Coloration is drab gray, off-white, or bright red
2. Many species have bioluminescent organs called photophores
3. Do not vertically migrate

Deep Sea Nekton

1. Deep sea Anglerfish-globular shape, bioluminescent lure on head
2. Deep sea Devilfish-globular shape, lure on head
3. Swallower-huge mouth, elongate body
4. Gulper-huge mouth, elongate body
5. Deep-sea Bristlemouths

Adaptations of Deep Sea Nekton

1. Coloration is drab gray, off-white, black or bright red
2. Biolumenescent photophores are fewer in number and more often located on the head and sides than on ventrum
3. Photophores are used to attract prey and communicate

Sensory Adaptations

1. Blind or with small, reduced eyes
2. Powerful sense of smell

Non-Migrators

1. Non-migratory because surface is to far away
2. Swim bladder reduced or absent
3. Flabby muscles & weak skeletons
4. Lack streamlining

Adaptations to Limited Food Supply

1. Small size
2. Huge mouths and expandible stomachs
3. Sluggish and sedentary
4. Poorly developed respiratory, circulatory and nervous systems

Reproductive Adaptations

1. Light and chemical attractants
2. Hermaphroditism
3. Reduced, parasitic males

Deep Sea Benthic Environment

1. Fine muddy sediment
2. Very little food and much of it is not immediately digestible
3. Benthic bacterial decomposers use the hard to digest detrital material
4. Chemosynthetic bacteria utilize the energy contained in various minerals to make organic compounds out of inorganic carbon compounds like carbon dioxide and methane

Deep Sea Benthos

1. Meiofauna are tiny animals that live between sediment particles and feed on bacteria
2. The macrofauna is dominated by deposit feeders which are nourished by meiofauna and bacteria
3. Diversity is high but abundance is low
4. Important invertebrate groups:
   • Echinoderms: sea cucumbers, brittle stars, and sea stars
   • Crustaceans: amphipods and crabs
   • Pycnogonids: sea spiders
   • Annelids: polychaetes
   • Molluscs: bivalves

Bottom Fishes

1. Relatively large, very elongated, dark brown to black in color, with strong muscles and small eyes.
2. Tripod fish - elongated pelvic and caudal fins provide a stand for perching on soft sediments
3. Hagfish - jawless with elongated snake-like body
4. Grenadier - large head with long narrow body
5. Eelpout - long body with dorsal, caudal and anal fins all fused into one fin
6. Brotulid - long body with dorsal, caudal and anal fins all fused into one fin
7. Spiny eel - long body, spiny dorsal fin, with caudal and anal fins fused into one

Adaptations of Deep Sea Benthos

1. Blind to nearly blind
2. Able to quickly locate large pieces of food that have fallen quickly to the deep sea floor (baitfalls)
3. For unknown reasons some species exhibit gigantism being very much larger than there shallow-water relatives
4. Grow slowly but live for a long time
5. Reproduce infrequently

Hydrothermal Vent Environment

1. Hydrothermal vents are deep sea hot springs in the volcanic rift zone of ocean ridges
2. Seawater circulates through the rift zone being superheated and enriched with sulfide minerals
3. Water temperatures at the mouth of a vent can exceed 600 degrees farhenheit
4. Minerals precipitate from the spring water forming streaming black clouds and forming tall mineral deposits called chimneys
5. The frigid seawater around the vents is warmed and enriched with hydrogen sulfide and methane
6. Chemosynthetic bacteria use the hydrogen sulfide and methane to produce organic compounds
7. The vents are surrounded by lush communities of organisms that utilize the production of the chemosynthetic bacteria for food

Hydrothermal Vent Fauna

1. Giant tube worms - giant pongonophoran worms with bright red gills that live in parchment tubes
2. Vent mussels - large white shelled mussels
3. Large vent clams - clams with red flesh that contains hemoglobin
4. Vent shrimp - shrimp with light sensitive patches that can detect the dim glow eminating from vents
5. Vent Crabs - white colored blind crabs

Adaptations of Hydrothermal Vent Fauna

1. Adapted to withstand dramatic temperature gradients
2. The giant tube worms do not have a mouth or a digestive tract
3. The giant tube worms, mussels and clams contain endosymbiotic chemosynthetic bacteria
4. The giant tube worms and clams contain specialized hemoglobin in their blood to bind and transport hydrogen sulfide to harmlessly deliver it to symbiotic bacteria in their tissues
5. Most species are able to chemically process hydrogen sulfide to prevent it from poisoning them
6. The mussels and clams are able to filter chemosynthetic bacteria for food
7. Vent shrimp graze on chemosynthetic bacterial films from vent chimneys
8. Vent organisms grow fast and large