Other important Zooplankton
Fig 6.5
Pareuchaeta (norvegica)
• Large (~8-10 mm) carnivores (tactile) at
several hundred meters depth. Active all
year
Pareuchaeta with egg sack
Pseudocalanus (lower) (and
Paracalanus)
• Pseudocalanus spp, intermediate sized (~1
mm) herbivores
• Life cycle with
dormancy at depth
• Egg sack
• (Calanus spawns
eggs freely)
Metridia
• Metridia spp; about the same size as Calanus
finmarchicus (ominvore, normally extensive
DVM, active all year)
Oithona
• Oithona spp small (< 1mm), omnivores,
abundant nearly everywhere
Oithona with egg sacks
Oncaea sp
• Oncea spp, small copepods (< 1 mm)
associated with particles (”marine snow”)
Oncaea on plankton net
Cadocerans, coastal forms
(Evadne left; Podon right)
Krill
Krill species:
* 3 important species in NS: in order of size:
Meganyctiphanes norvegica, Thysanoessa inermis, T. longicaudata
* Several different larval types,
each with several stages:
Nauplius->metanauplius->calytopis->furcilia
* Pronounced DVM
* Schooling/swarming occurs
* Macroplankton/Micronekton?
Meganyctiphanes norvegica
Meganyctiphanes norvegica
* Northern krill (Storkrill)
* Distribution: From Atlantic from
Mediterranean to nearly polar
* Size up to about 40 mm
* Maturity at 1 year in the Oslofjord, 2 years in NS
* Longevity 2-3 years?
Meganyctiphanes norvegica
* Omnivorous
* Filter feeding on phytopl.
* Raptorial on zooplankton
* Wide range of prey
Thysanoessa inermis
Thysanoessa inermis
* Distribution: North Atlantic
* Primarily on shelves
* Near bottom during winter?
* Max length 35 mm
* Maturity at 1 y.o.
* Longevity 2-3 yrs
Thysanoessa longicaudata
* Distribution: Atlantic/Subarctic
* Basin species
* Max length 20 mm
* Maturity at 1 yrs
* Longevity 2 yrs
Krill
* Feeding: Generally omnivorous or herbivorous, T.
longicaudata likely largely carnivores
* Filtering basket
* Relatively high clearance rates (vol. Filtered)
* Raptorial on zooplankton
Amphipods: Themisto libellula
* Max size about 60 mm
* Arctic distribution
* Direct development of
freeswimming young
(brood chamber)
* Maturity at 2 yrs
* Longevity 2-3 yrs
* Raptorial predator (visual)
Pelagic shrimps (Sergestes
arcticus)
• Carnivores at mesopelagic depth
• Normal DVM
Sergestes arcticus
Other important zooplankton
* Chaetognaths
- Predators
* Cnidaria
- Predators
- Periphylla
- Holoplanktonic species
- Aurelia/Cyanea
Other important zooplankton
* Ctenophores
- Predators
* Pteropods
* Limacina-herbivore
* Clione-carnivore
Appendicularians
- Filterfeeders
- Extremely fine filters
- Rapid turnover