Zooplankton, Deep Sea Nekton Flashcards
What are zooplanktons three mechanisms of buoyancy?
- Body size: small size increases S:V ratio and friction with water column
- Appendages and projections: help with S:V
- Density: high lipid content, air bladders
Mesoplankton
Zooplankton (e.g. copepods)
0.2-20 mm
What type of zooplankton are the eggs considered?
Microplankton and mesoplankton
Macroplankton
Zooplankton
2-20cm
Megaplankton
Zooplankton
20cm-2m
What are the three groups of zooplankton?
- Mesoplankton (0.2-20mm)
- Macroplankton (2-20cm)
- Megaplankton (20cm-2m
Neuston
Planktonic organisms living at the sea surface
- Includes all size zooplankton and phytoplankton
Pleuston
A type of neuston that includes plankton forms that break the surface and use wind for dispersal
Meroplankton
Organisms with a life stage in the plankton and another in the benthos
Holoplankton
Organisms with a full cycle in the water column
Dynamics of movement on fluid
- Streamlining and body shape: Reduces water resistance
- Reynolds number (Re): The ratio or coefficient of drag
- Countershading and Color
- Nekton Diversity
Body shapes of fish
Fusiform: shaped for fast, long swimming (tuna, sharks)
Laterally compressed: shaped to make tight, close turns (rock fish)
Eel-like: shaped to live in between sea grass, rock
Depression or Flat: shaped to rest or hide in the bottom (flounders)
Objects with a high Re…
Dynamics driven by objects large size and speed
- object continues to move because they have a momentum
Objects with a low Re…
Dynamics driven by water viscosity
- After source of movement stops, object stops
Countershading
dark on top, light on bottom
- Most basic camouflage
Nekton diversity
- Invertebrates and reptiles
- Fish
- Deep sea fish
- Marine mammals
- Seabirds
- Fisheries
Two groups of fish
bony
cartilaginous (sharks and skates)
Characteristics of cartilaginous fish
- Placoid scales
- Heterocercal tail
- Exposed gill slits
- Large pectoral fins
Characteristics of bony fish
- Cycloid scales
- Homocercal tail
- Operculum present
- Small pectoral fins
- Jaw morphology
Four relevant families of bony fish
- Scrombridae (mackerel, tuna)
- Salmonidae (salmon and trouts)
- Pleuronectiforms (flatfish)
- Gadidae (cod and hake)
Characteristics of the fish family: Scrombridae
- Most schooling fish in surface waters
- Migration
E.g. mackerel
Characteristics of the fish family Salmonidae
- Marine and freshwater species
- Migratory but native to North hemisphere
- Carnivorous
E.g. salmon
Characteristics of the fish family Pleuronectiforms
- Asymmetrical as adults, flattened body
- All marine
E.g. flounders
Characteristics of the fish family Gadidae
- Marine
- Slow growing
- Long life span
E.g. cod
Collapse of cod stocks
Allowed the build up of shrimp and crab
Fishing down the trophic web
Overfishing; as top predators are removed from fishing, smaller fish lower in the web are targeted, reducing their numbers
zones of the deep sea
Meso, bathy, Abyssopelagic
How does the habitat of the deep sea compare to the epipelagic zone?
- 10 times less abundant
- lack of primary production
- darker, colder, higher pressure
Mesopelagic zone
- Some twilling light but no photosynthesis
- Zone where permanent thermocline occurs
- Zone where the OML (oxygen minimum layer) occurs
Where does the mesopelagic zone get its oxygen from?
- Atmosphere exchange
- Photosyntheis
- Ocean conveyor belt
Why is there a small increase in oxygen below the OML? (Oxygen minimum layer)
Lack of nutrients
4 adaptations of the mesopelagic
- Bioluminescence and photophores: photophores located on ventral side; bioluminescent cells
- Sensory organs: Large, highly sensitive eyes
- ‘Hungry’ anatomy: Specialized feeding anatomy
- Vertical migration ability
Conditions of the Abyssopelagic
- Always dark
- Always cold (1-2 degrees Celsius)
- Under higher pressure
Adaptations to the Abyssopelagic
No need for swim bladders, streamlining, colors, large eyes
