Oceanic Nekton Flashcards
Adaptations of oceanic nekton
Buoyancy locomotion surface of resistance and body shape defence and camouflage sensory systems echolocation reproduction lifestyle migrations
What are protogynous hermaphrodites? (With example)
Start off female
E.g. Parrotfish
What are protoandrous hermaphrodites? (With example)
Start off male
E.g. Clownfish
What does diadromous mean?
Organism is both freshwater and marine
E.g. Salmon
What does anadromous mean?
Adults return to freshwater (from marine)
E.g. Salmon
What does catadromous mean?
Adults return to marine to spawn (from freshwater)
E.g. Eels
What is a method of colour camouflage in netritic fish?
Counter-shading colouration
- dark on top (blends with darkness of depths)
- shiny on bottom (blends with light/sun)
What does a high aspect caudal fin ratio mean? (With example)
Fast swim pace but short distance
E.g. Tuna
What does a low aspect caudal fin ratio mean? (With example)
Short rapid acceleration but long distance
E.g. Cod
What does white muscle mean?
Poor muscle blood supply
What does dark muscle mean?
Good muscle blood supply
What do the median fins do?
Aid stability
What types of lift are there?
Buoyancy
Hydrodynamic
What aids hydrodynamic lift?
Fins & tail
What aids buoyancy?
Swim bladder/oil-rich liver
What is globiform?
Fish shape like a ball - e.g. Pufferfish
What is fusiform?
Fish streamlined and built for speed - e.g. Tuna
What is sagittiform?
Arrow-like shape - e.g. Needlefish
What is compressiform?
No width, laterally flattened - e.g. Flatfish
What is depressiform?
No depth, dorso-ventrally flattened - E.g. Manta ray
What is anguilliform?
Elongated, rounded body - e.g. Eels
What is taeuiform?
Ribbon-shaped
What is filiform?
Filament-like
where is the epipelagic zone?
0-200m
where is the mesopelagic zone?
200m-1km
where is the bathypelagic zone?
1km-4km
where is the hadalpelagic zone?
> 4km
where are benthicpelagic organisms found?
sea floor and water column to feed
where are benthic organisms found?
sea floor/in sea bed
where are pelagic organisms found?
in the water column
where is the littoral zone?
between the high and low tide, exposed and submerged for different portions of the day
where is the netritic zone?
from the low end of low tide to when the continental slope slopes down steeply
order of seafloor names from coast to ocean
coast continental shelf continental slope continental rise abyssal plain
what is a key adaptations for the neritic zone?
protections from irritation by pollutants
e.g. membrane across eyes of squid to protect from irritants
what does holopelagic mean?
fish that spend whole life in pelagic zone
what does meroplanktonic mean?
fish that spend part of life in pelagic zone
where did most fishing historically occur?
the pelagic zone - deeper depths only recently
what is the visual-interactions hypothesis?
The metabolism of several animal groups declines with depth even after adjustments for size and temperature.
why? as the result of declining light levels that reduce the distances over which predators and prey interact.
- > relaxes the selective pressure for locomotory capacity
- > reductions in metabolic
where is the visual-interactions hypothesis most pronounced and why?
pelagic species - no refuge from predators.
-> less depth-related variation among benthic species.
what is a small-scale example of a regime shift?
coral reefs - coral dominated VS algae dominated
Hurricane Allan in Caribbean -> rainfall reduced water salinity
-> coral deaths
-> algae dominated coral reefs
what is an intermediate-scale example of a regime shift?
North Sea - more water from Atlantic Ocean
- > changes in plankton community
- > more jelly fish but less cod
- > less herring and haddock (juvenile predated by jellyfish)
what is a large-scale example of a regime shift?
North Pacific Ocean - warming in the Winter Pacific Oscillation (starting in mid 1970s)
-> reduction in Chinook salmon but increase in pink salmon
what is a behaviour of fish species which can reduce by-catch percentages?
shoaling (all together)
when calculating swim speed for fish what is Hz referring to?
number of tail flicks a second
what is a physostomous swimbladder?
open to gut- gulp air
what is a physoclistous swimbladder?
closed
what is a swimbladder solution to increased pressure with depth?
rigid container
what is a pattern on the distribution of fish with swimbladder?
more swimbladder fish closer to the surface
What is a method of shape camouflage in netritic fish?
keel - sharp ventral edge tail
e.g. tuna
sharks and rays special sensing organ
ampullae Lorenzini
electrical signals
amphidromous
migrate for purpose other than reproduction
potamodromous
migrate wholly within freshwater
oceanodromous
live and migrate wholly within seawater
magnetotactic bacteria
use of magnetic fields in migration
more invasive fish species tend to be…
planktivorous
