Zooplankton Flashcards
What are meroplankton and what are the advantages?
Meroplankton are species that have part of their lifecycle in the planktonic stage.
Approx. 80% benthic species have a larval stage. Some stay in the planktonic stages for weeks or months depending in advantageous conditions of the species.
Benefits of small planktonic stage – develop to sexual maturity faster, drift further from colonies
What are some of the adaptations in the blue crab larva?
See through, can’t be seen.
Star shape to stop settling.
In early larval stages (top right) large spines stops predation from smaller predators.
What are some of the adaptations in larval fish?
Yolk sac
Transparancy
Fish eggs have lipids and oils to aid buoyancy
What are the two larval stages of a crab?
Megalopa – later laval crab stage
Zoeal – early larval crab stage
List categories of holoplankton (permanant residents) in terms of their size
Smallest - protists (micro-organisms)
Medium - Chaetognatha/arrow worms (1-4cm)
Large - Comb jellies, jellyfish (many metres wide and long)
Give examples of two gelatinous zooplankton
medusa and siphonophore
Give some examples of holoplankton
Portugese man o war – colonial hydroid, class next to jellyfish. Gas bladder projects above the water – neuston category
Moon jellyfish
Teptroptimous – long antennae and chaete
Copepods
What are some adaptations of arrow worms?
Strong hooks around the mouth to catch prey.
Good at picking up vibration in the water
What are some adaptations of Ctenophores?
Cone rows of scilia
Trailing tentacles with adhesive cells to catch prey – often copepods.
What species dominates the plankton group?
The copepods make up 70% of net-collected plankton.
Describe the body organisation of the Copepods
Head and first body segment are fused together and contain antennae and mouth parts.
Body segment contains swimming legs and lastly the tail which has no appendages.
How do copeppods feed?
Antennae swoop once food is deteced on the hairs of the antennae bringing in water and maxillipeds make a circular movement grabbing food with maxillary setules.
Diet preference; two celled chains to single cells and prefer larger diatoms.
Why do zooplankton undertake a diurnal vertical migration, ascending to surface at dusk and descending to depths at dawn?
- Avoid strong uv radiation
- allow phytoplankton to recover
- avoid predation
- conserve energy
- optimal foraging
What is the match/mismatch hypothesis and who proposed it?
D.H Cushing proposed the hypothesis.
He noted that climatic factors control the timing and strength of phytoplankton blooms which affects zooplankton feeding and larval fish.
‘Mismatch’ phytoplankton blooms occur earlier/later/reduced than expected.
What affects can be caused due to phytoplankton mismatch?
When zooplankton and phytoplankton align, you get very good fish stocks. However if PP blooms earlier or later than zooplankton alignment, fish stocks tend to be strongly influenced by timing of prey. Not only for prey but for food for fish offspring.
Plankton mismatch means that prey can differ in size and species which can affect those dependant on them for food.