RABIYA NASIR

M.PHIL STUDENTINSTITUTE OF MARINE SCIENCE

ZOOPLANKTONS OF MARINE ECOSYSTEM

* OBJECTIVES:

:Be able to define zooplankton.:Be familiar with the major. groups of zooplankton and their characteristics.:Explain the benefits of zooplankton.:Explain how certain zooplankton can

gauge reproductive success.

CLASSIFICATION OF MARINE ORGANISMS:

• Plankton (floaters)• Nekton (swimmers)• Benthos (bottom dwellers)

PLANKTONS: Plankton (singular plankter) are any

organisms that live in the water column and are incapable of swimming against a current . They provide a crucial source of food to

many large aquatic organisms , such as fish and whales.

These organisms include drifting animals, protists , archaea , algae, or bacteria that inhabit the pelagic zone

of oceans, seas, or bodies of fresh water. That is, plankton are

defined by their ecological niche rather than phylogenetic or taxonomic

classification.

ZOOPLANKTON*Planktonic animals

can be found in almost all animal phyla

*Most zooplankton belong to 3 major groups: rotifers, Cladocera , and

Copepoda

*One other group may, at times, be important:

Protozoa

*Spend only portion of lives in plankton (mostly

sediment-dwelling)

*Feed on bacteria, detritus (little used by other

zooplankton)

IMPORTANT ZOOPLANKTON GROUPS:

*ProtozoaCiliates, Amoebae

*Rotifera*Copepods

*Gelatinous Zooplankton*Invertebrate and Vertebrate

Larvae

Protozoa*Single cell organisms.

*Primarily feed on bacteria and phytoplankton.

*Capable of reproducing rapidly due to small size.*Most species capable of

forming cysts Microzooflagellates, ciliates,

amoebae.

Ciliates and Amoebae

ROTIFERA: Typically referred to as

“Rotifers” “sloppy feeders” on

phytoplankton and other zooplankton

recycle nutrient via feeding and fecal pellets

parthenogenic eggs

Rotifers: Mostly littoral, sessile, but

some are completely planktonic

May be dominant zooplankton in some lakes

Omnivorous, small (<12 µm)

Filter-feeding with corona

ROTIFER USE BY FISH Too small to be

important as food for most fish

May be important in diets of some larval fish

Rotifers are potential prey for predatory copepods

Vertical migration upward at midday to avoid copepods

COPEPODS:• “Sloppy feeder” on

phytoplankton and other zooplankton

• Major source of food for larval fish

• Recycles nutrients via feeding and fecal pellets

COPEPODA:

• Microcrustaceans in same size range as cladocerans

• Several different groups based on differences in body structure

• 2 major groups: cyclopoids and calanoids

COPEPODA:• Cyclopoids - short

1st antennae• Cyclopoids - most

are littoral, but few are open-water planktonic forms

• All seize food particles and bring them to mouth - raptorial

COPEPODA:

GELATINOUS ZOOPLANKTON:• Commonly referred to

as jellyfish• Most have stinging

cells called cnidocytes but some are filter feeders

• May be permanent of temporary members of the plankton

CTENOPHORES:• Cteno means comb:

sometimes called comb jellies

• Gelatinous filter feeding organisms- no stinging cells

• May be bioluminescent

• Common in the Bay in the early Spring

COMB JELLIES:

CNIDARIANS:

• Stinging cells• Chrysaora quinequecirrha• Stinging and feeding

tentacles• Male and female forms• “jelly” is the sexual stage

of the life cycle and is called the medusa stage

OTHER CNIDARIANSHYDROMEDUSA, PORTUGESE MAN-O-WAR

LARVAE OF INVERTEBRATE AND VERTEBRATE ANIMALS

• Temporary members of the plankton

• Invertebrates are animals without backbones: worms, oysters, crabs

• Vertebrates are animals with backbones: fish

They aren’t always “small!”

Some large gelatinous zooplankton: (c) A colony of salps (Pegea) cloned from a single parent.

Barnacles: benthic sessile crustaceanBARNACLES: BENTHIC SESSILE

CRUSTACEAN

Cnidaria (siphonophora)

FLOATING ZOOPLANKTON:

• Microscopic zooplankton have shells or tests.–Radiolarians–Foraminifers–Copepods

LIFE CYCLES IN ZOOPLANKTON

• Holoplankton: spend entire life in the water column (pelagic)

• Meroplankton: spend only part of their life in the pelagic environment, mostly larval forms of invertebrates and fish

• Ichthyoplankton: fish eggs and fish larvae

SEASONAL:• Maximum in the spring– Temperate areas (spring,

fall, summer, winter)– Polar areas (spring,

summer, fall, winter)– Food supply (concentration

and type)– Life cycle of the

zooplankter

EXCRETION:• Release of soluble material– Ammonia (Urea, free amino acids, DOC)– Younger stages excrete more per unit

weight (Not total volume)– Decreases with temperature– Related to grazing