Zooplankton Dr. Jason Turner MARE 444

Zooplankton Protozoans (Kingdom Protista) Size varies from microns (μm) to meters (m)

They’re Heterotrophic Herbivores – Carnivores – Detritivores – Omnivores – Planktivores -

Zooplankton Stenohaline - (limited to a narrow range of salinity) found near mouth of estuary Euryhaline - (more tolerant of salinity variation) penetrating further up estuary Estuarine - species confined to estuary Freshwater - species normally found in freshwater

Planktonic Life Styles Holoplankton – Meroplankton -

Collecting Plankton

Collecting Plankton Horizontal tow Vertical tow Oblique tow Mesh size Gear avoidance Volume of water sampled Fragile organisms

Flow Cam Images

Flow Cam Images

Protozoans Single celled Small (often overlooked)

Protozoans Dinoflagellates Zooflagellates Foraminiferans Radiolarians Ciliates

Dinoflagellates Peduncle - a cytoplasmic extension used in phagotrophy Half of dinos are heterotrophic

Dinoflagellates

Zooflagellates Strictly heterotrophic (microbial loop?) Typically 2-5 m in length High reproductive rates 20-80% of nanoplankton = food source

Zooflagellates

Foraminiferans Phylum Foraminifera Amoeboid critters with a shell (test) made of calcium carbonate Test can be used to ID species and reconstruct past environments Rhizopods, feed on bacteria, phytos, zooplankton Chalk, White Cliffs of Dover, ooze

Foraminiferans

Radiolarians Phylum Polycystina Amoeboid critters with silica shells Shells are typically spherical with radiating spines Pseudopodia Common in cold waters Some are deep-sea species Siliceous ooze

Oozes

Radiolarians

Ciliates Phylum Ciliophora Hair-like cilia used in locomotion and feeding Specialized, advanced cells

Ciliates

Microbial Loop

Holoplanktonic metazoans Most primitive are cnidarians Jellyfish (medusae) some are holoplanktonic, others are meroplanktonic all are carnivorous Siphonophores colonial forms; Physalia Box jellies: Chironex

Medusae

Siphonophores & Box jellies

Ctenophores Phylum Ctenophora Look like jellyfish, but have 8 rows of fused cilia Do not sting

Ctenophores

Chaetognaths Phylum Chaetognatha Arrow worms Carnivorous Rapid swimmers – long trunk muscles

Chaetognaths

Polychaetes Phylum Annelida, Class Polychaeta Tomopteris - a planktonic worm 40 species, all predators

Tomopteris

Holoplanktonic mollusks swim by undulating a single fin some have reduced, or absent shell visual predators warm, oceanic water

Heteropods

Pteropods Sink to bottom produce pteropod ooze Thecosomes most have a shell suspension feeders Gymnosomes (naked pteropods)

Pteropods

Crustaceans Phylum Arthropoda Class Crustacea Very common planktonic animals Copepods are most common

Copepods Order Calanoida 1850 species ubiquitous 12 different stages of development from egg to adult - easy to study

A calanoid copepod

Copepod Life Cycle

Cyclopod copepods Order Cyclopodia 250 planktonic species

A cyclopod copepod

Harpacticoid copepods Coastal, or associated with the benthos 20 species are holoplanktonic No distinct divisions between body regions May be seasonally or locally abundant, but ecological importance is not great

An harpacticoid copepod

Euphausiids Shrimp-like animals 86 species Euphausia superba -

Euphausiid

Amphipods Laterally compressed body Some are parasitic, others are carnivorous, etc.

Amphipods

Ostracods Unique, hinged bivalved exoskeleton Scavengers? Usually small, deep-sea individuals can get big Little work has been done on this group

Ostracods

Cladocera Mainly a freshwater group, 8 marine species Daphnia - the water flea Coastal and brackish water Primitive group - capable of producing cloned offspring (parthogenesis)

Cladocera

Mysids Spend most of the time on sea floor, rise in the water column to feed at night Estuarine, nearshore waters Harvested in Asia

Mysids

Decapods Omnivores or carnivores Active at night, vertical migrations Important prey for tuna, dolphins, and whales

Shrimp

Chordates Phylum Chordata Appendicularians 70 marine species also called larvaceans make a mucus house marine snow filter feeders

Larvaceans

Salps Asexual budding Hermaphorditic r-selected organism

Salps