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Zooplankton

Zooplankton. http://www.microscopy-uk.org.uk. Planktos: “drifts” in greek. Their distribution depends on currents and gyres Certain zooplankton can swim well, but distribution controlled by current patterns

damian-clements
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Zooplankton

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  1. Zooplankton http://www.microscopy-uk.org.uk

  2. Planktos: “drifts” in greek • Their distribution depends on currents and gyres • Certain zooplankton can swim well, but distribution controlled by current patterns • Zooplankton: all heterotrophic plankton except bacteria and viruses; size range from 2 µm (heterotrophic flagellates, protists) up to several meters (jellyfish)

  3. Herbivorous zooplankton: Grazers

  4. Nutritional modes in zooplankton • Herbivores: feed primarily on phytoplankton • Carnivores: feed primarily on other zooplankton (animals) • Detrivores: feed primarily on dead organic matter (detritus)  • Omnivores: feed on mixed diet of plants and animals and detritus

  5. Feeding modes in Zooplankton • Filter feeders • Predators – catch individual particles

  6. Filter Feeder Copepod

  7. Filter Feeder Ctenophore

  8. Predator Chaetognath Arrow Worm

  9. 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

  10. Holoplankton Copepods Planktonic crustaceans

  11. Barnacles: benthic sessile crustacean http://science.whoi.edu/labs/pinedalab/

  12. Meroplankton Nauplius larva http://www.microscopy-uk.org.uk

  13. Meroplankton Cypris larva http://www.microscopy-uk.org.uk

  14. http://science.whoi.edu/labs/pinedalab/

  15. Cypris larva and metamorphosed juveniles http://science.whoi.edu/labs/pinedalab/

  16. Barnacle population regulation http://science.whoi.edu/labs/pinedalab/

  17. Ichthyoplankton Gadidae Gadus morhua

  18. Gadidae Gadus morhua Ichthyoplankton

  19. Gadidae Gadus morhua Ichthyoplankton

  20. Gadidae Atlantic cod Gadus morhua Demersal Adult

  21. Protists: Protozooplankton • Dinoflagellates: heterotrophic relatives to the phototrophic Dinophyceae; naked and thecate forms. Noctiluca miliaris – up to 1 mm or bigger, bioluminescence, prey on fish egg & zooplankton • Zooflagellates: heterotrophic nanoflagellates (HNF): taxonomically mixed group of small, naked flagellates, feed on bacteria and small phytoplankton; choanoflagellates: collar around flagella • Foraminifera: relatives of amoeba with calcareous shell, which is composed of a series of chambers; contribute to ooze sediments; 30 µm to 1-2 mm, bacteriovores; most abundant 40°N – 40°S

  22. Dinoflagellates Noctiluca miliaris

  23. Colonial choanoflagellates Bacteriofages (Ross Sea) http://www.nsf.gov/pubs/1999/nsf98106/98106htm/ht-015.gif

  24. Foraminifera (calcareous – all latitudes)

  25. Protists: Protozooplankton • Radiolaria:spherical, amoeboid cells with silica capsule; 50 µm to several mm; contribute to silica ooze sediments, feed on bacteria, small phyto- and zooplankton; cold water and deep-sea • Ciliates:feed on bacteria, phytoplankton, HNF; naked forms more abundant but hard to study (delicate!); tintinnids: sub-group of ciliates with vase-like external shell made of protein; herbivores

  26. Figure 3.21b Radiolarians (siliceous – low latitudes)

  27. http://www.jochemnet.de/fiu/

  28. Live Radiolarian http://www-odp.tamu.edu/public/life/199/radiolaria.jpg

  29. Invertebrate Holoplankton • Cnidaria: primitive group of metazoans; some holoplanktonic, others have benthis stages; carnivorous (crustaceans, fish); long tentacles carry nematocysts used to inject venoms into prey; box jellyfish of Australia kills humans within minutes • Medusae: single organisms, few mm to several meters • Siphonophores: colonies of animals with specialization: feeding polyps, reproductive polyps, swimming polyps; Physalia physalis (Portuguese man-of-war), common in tropical waters, Gulf of Mexico, drifted by the wind and belong to the pleuston (live on top of water surface)

  30. Cnidaria (medusae)

  31. Cnidaria (medusae)

  32. Cnidaria (siphonophora)

  33. Invertebrate Holoplankton • Ctenophores:separate phylum, do not belong to Cnidaria; transparent organisms, swimm with fused cilia; no nematocysts; prey on zooplankton, fish eggs, sometimes small fish; important to fisheries due to grazing on fish eggs and competition for fish food • Chaetognaths: arrow worms, carnivorous, <4 cm Polychaets: Tomopteris spp. only important planktonic genus

  34. Ctenophora (comb jellies)

  35. Ctenophora (comb jellies)

  36. Invertebrate Holoplankton • Mollusca:  • Heteropods: small group of pelagic relatives of snails, snail foot developed into a single “fin”; good eyes, visual predators • Pteropods: snail foot developed into paired “wings”; suspension feeder – produce large mucous nets to capture prey; carbonate shells produce pteropod ooze on sea floor

  37. Heteropod (Predates on Ctenophores)

  38. Pteropod http://www.mbari.org/expeditions/

  39. Protochordate Holoplankton • Appendicularia: group of Chordata, live in gelatinous balloons (house) that are periodically abandoned; empty houses provide valuable carbon source for bacteria and help to form marine snow; filter feeders of nanoplankton • Salps or Tunicates:group of Chordata, mostly warm water; typically barrel-form, filter feeders; occur in swarms, which can wipe the water clean of nanoplankton; large fecal bands, transport of nano- and picoplankton to deep-sea; single or colonies

  40. Appendicularia

  41. Pelagic Salps

  42. Arthropoda: crustacean zooplankton • Cladocera (water fleas): six marine species (Podon spp., Evadne spp.), one brackish water species in the Baltic Sea; fast reproduction by parthenogenesis (without males and egg fertilization) and pedogenesis (young embryos initiate parthenogenetic reproduction before hatching) • Amphipoda: less abundant in pelagic environment, common genus Themisto; frequently found on siphonophores, medusae, ctenophores, salps • Euphausiida: krill; 15-100 mm, pronounced vertical migration; not plankton sensu strictu; visual predators, fast swimmers, often undersampled because they escape plankton nets; important as prey for commercial fish (herring, mackerel, salmon, tuna) and whales (Antarctica)

  43. Amphipoda

  44. Amphipoda (parasites of gelatinous plankton)

  45. http://www.imagequest3d.com/catalogue/deepsea/images/l038_jpg.jpghttp://www.imagequest3d.com/catalogue/deepsea/images/l038_jpg.jpg

  46. Euphasids (krill)

  47. Arthropoda: crustacean zooplankton • Copepoda:most abundant zooplankton in the oceans, “insects of the sea“; herbivorous, carnivorous and omnivorous species • Calanoida: most of marine planktonic species • Cyclopoida: most of freshwater planktonic species • Harpacticoida: mostly benthic/near-bottom species • Copepod development: first six larval stages = nauplius (pl. nauplii), followed by six copepodit stages (CI to CVI) • Tropical species distinct by their long antennae and setae on antennae and legs (podi)

  48. Copepods

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