Arthropoda: Pancrustacea (Copepoda)

Question 1

General Characteristics (6)

Answer 1

Extremely abundant
Aquatic food webs (primary consumers)
Small body size (1-2 mm)
Diverse aquatic habitats (freshwater and marine)
Free-living (holopelagic or pelago-benthic)
Parasitic (1/3 of all described species)

Question 2

Body Plan (9)

Answer 2

Torpedo (teardrop) shape
Median ocellus (retained from nauplius; no compound eye)
1st pr. antennae - sensory
2nd pr. antennae - swimming
Pair of mandibles & 1st pair maxillae
2nd pair maxillae - food capture 
One pair of maxillipeds - assist feeding
4-5 pair thoracic appendage - hopping swimming 
Forked telson

Question 3

Open ocean copepods environmental parameters (5)

Answer 3

Pull of gravity
Depth-dependent light intensity
Nowhere to hide
Dilute resources (food, mates)
Small Reynolds number

Question 4

Reynolds Number

Answer 4

Describes relative importance of viscous vs inertial forces for characterizing the behaviour of fluids flowing past an object
Re = (velocitysizedensity)/viscosity

Question 5

Small Reynolds Number vs Large Reynolds Number

Answer 5

Small: flow dominated by viscous forces that generate laminar flow, thick boundary layer

Large: flow dominated by inertial forces that generate turbulent flow, thinner boundary layer

Question 6

How do copepods avoid predators

Answer 6

Mostly transparent so they are hard to detect by predators
Active stroke of thoracopod for escape
Diel-vertical migration to avoid predators

Question 7

How do copepods find mates (2)

Answer 7

Pheromones are released from the females so that males can track them
Behavioural swimming patterns: Males swim at a constant height, moving horizontally and females move up and down in the water column