Marine Zooplankton

Question 1

Holoplankton

Answer 1

organisms which spend their whole life as plankton

Question 2

Meroplankton

Answer 2

organisms which have only part of their life cycle in the plankton. An example is larvae of barnacles or crabs. Many benthic organisms have part of their life cycle as meroplankton.

Question 3

About——of benthic organisms have a planktonic stage

Answer 3

70%

Duration of the planktonic stage ranges from minutes to even years in some exceptional cases

Question 4

trochophore larvae

Answer 4

small, translucent, free-swimming larva characteristic of marine annelids and most groups of mollusks. Trochophores are spherical or pear-shaped and are girdled by a ring of cilia (minute hairlike structures), the prototroch, that enables them to swim.

Question 5

After the Trochophore stage, benthic snails and clams produce ……

Answer 5

shelled veliger larvae

Question 6

Zooplankton size ranges

Answer 6

Picozooplankton 2-20µm
Microzooplankton 20-200 μm
Mesozooplankton 200 μm-2 mm
Macrozooplankton 2-20 mm

Question 7

There are many diverse classes of zooplanktonic holoplankton….

Answer 7

Crustacea (copepods, krill, many meroplankton
Cnidaria (siphonophores, medusa)
Molluscs (pteropods)
Appendicularians (salps & larvaceans)
Ctenophores (comb jellies)
Picozoa 2-3 µm heterotrophs

Question 8

Picozoa

Answer 8

a new phylum — Originally called Picobiliphytes, they were found to contain phycobiliproteins (PB) and thought to be photosynthetic.
However, the PB came from cyanobacteria eaten by the organisms.
Very widespread!

Question 9

Crustacea

Answer 9

are members of the phylum Arthropoda. Examples of Crustacea are: lobsters, shrimp, copepods and crabs. The arthropods include 80% of all animal species on Earth and include spiders, scorpions, insects, mites, millipedes, centipedes etc.

Question 10

what supports and protects the exoskeleton of crustaceans?

Answer 10

chitin (a nitrogenous polysaccharide)

cellulose and starch are the three most abundant organic compounds in nature. Chitin is a polysaccharide with an amide (with N) group attache

Question 11

Crustaceans Body Plan

Answer 11

have two pairs of antenna and limbs with 7 segments

All crustaceans have a nauplius (larval) stage in their life cycle

Question 12

Crustacean larval called?

Answer 12

nauplius – molt about 6 times before developing into the next stage

Question 13

If so many zooplankters are molting, why isn’t the ocean filling up with chitin?

Answer 13

Bacteria (Vibrio) detect the chitin, swim to it and synthesize enzymes to break it down

Question 14

Chitosan-based DNA nanoparticle for gene delivery and transfection….

Answer 14

Chitosans, typically isolated from the shell of shrimp, has the ability to react with DNA and compact it to produce a nanoparticle. Such nanoparticles are more readily taken up by cells. In this way we can transfer novel genes into cells, either for therapeutic purposes (gene therapy)

Question 15

Copepoda

Answer 15

subclass of Crustacean members of the zooplankton Most abundant group of animals on Earth. Picozoa probably more abundant!

Question 15

Copepoda

Answer 15

subclass of Crustacean members of the zooplankton Most abundant group of animals on Earth. Picozoa probably more abundant!

Question 16

In developing, copepods must

Answer 16

molt or shed their exoskeleton. This is because as they grow, their exoskeleton becomes too small for their body.

Usually go through 6 naupliar and 6 copepodite stages before becoming an adult

Question 17

Copepods use their antenna for…

Answer 17

sensing the environment

Question 18

Antenules (NOT antenna) in copepods are used for…

Answer 18

Antennules are used in swimming

Question 19

Copepod life cycle

Answer 19

egg –> 6 nauplii stages –> 5 copepodid stages

egg, nauplius, copepodite, and adult

Question 20

Why could C. finmarchicus (copepod) have a diapause stage?

Answer 20

winter goes into a diapause stage where metabolism slows, stops feeding, and it goes to deep water

like hibernation, not as much food available ?

Question 21

it has been discovered that both diatoms and dinoflagellates can depress copepod reproduction, why?

Answer 21

When certain species are eaten, copepod egg and fecal pellet production and hatching success is depressed

Three different aldehydes were isolated from diatoms that are responsible

Question 22

Euphausids

Answer 22

Euphausia superba is “Krill” of Southern Ocean.

~85 species
~ 80 mm (3 inches) long

Spawn Jan-March in Antarctic waters. Eggs sink to ~ 1800 m. Naupliar stages slowly swim upward in time to feed on austral summer phyto blooms which start in October. Next 2 yrs grow to 6 cm in length and live in upper 200 m

Question 23

Euphausid life cycle

Answer 23

Eggs sink & hatch in
Spring. Reach the
Furcilia stage by
winter

Question 24

Appendicularians (LARVACEANS)

Answer 24

Chordates (Phylum Chordata) which are closely related to benthic tunicates (sea squirts) Because they resemble larval stages of benthic species they are called larvaceans Look like a tadpole Builds a mucoid house and filter to collect food. Filter becomes clogged and is discarded (ca 10X/day). Can have ~ 1000 discarded houses/m3 Contribute to “marine snow.” Marine snow sinks relatively rapidly to the bottom and is food for deep sea benthos ~ 70 species

Question 25

Larvaceans have a

Answer 25

primitive “backbone” or notochord

Question 26

Salps

Answer 26

chordates The large aggregates can be 15 m long Aggregate stage has hermaphroditic (both sexes in one individual) salps which produce sperm & egg (at different times) Fertilized eggs grow to be a solitary salp which then reproduces by budding until the large aggregate is formed Have very rapid growth rates Typically found in warm waters, not polar regions, but with global warming are invading polar areas

Question 27

what is the reproduction of salps like?

Answer 27

sexual and asexual reproduction soliary stage (asexual) --> aggregated stage (sextual) ---> aggregate with embryo --> embryo

Question 28

Pyrosomes

Answer 28

bioluminescent & are also tunicates, colonial filter feeders. Zooids are a few mm in size and embedded in a gelatinous tunic, tropical... the really big long tube things

Question 29

Phylum Cnidaria, name the classes?

Answer 29

Hydrozoa, Scyphozoa, Anthozoa

Question 30

Anthozoa

Answer 30

(sea anemone & stony corals)

Question 31

Scyphozoa

Answer 31

(large jellyfish)

Question 32

Hydrozoa

Answer 32

(small jellyfish, siphonophores & hydroids)

Question 33

Siphonophores

Answer 33

Siphonophores are colonial hydrozoan jellyfish that range from the surface to the deepest waters. The group is poorly known from conventional plankton net samples because the delicate colonies often are damaged beyond recognition during capture. Surface species often have small gas-filled floats and prey on zooplankton. They contain a complex of medusoid and polyploid members that function together as an organism. A primitive nervous system coordinates the individuals.

Question 34

Nematocysts

Answer 34

(stinging cells)

Question 35

Scyphomedusa

Answer 35

large jellies, have nematocysts,

Question 36

Ctenophores

Answer 36

``` Do not move by pumping water Use cilia to move Do not have nematocysts (stinging cells) Very big predator on copepods Can become very abundant (NOT in the cnidarian phyulm) ```

Question 37

Phylum Mollusca

Answer 37

``` Pteropods -- Planktonic molluscs Foot is modified to be a wing like appendage 2-5 cm in size (1-2 in.) Flap wings like a butterfly See prey with their eyes ```

Question 38

Pteropod

Answer 38

Pteropod (winged foot) is a term to cover two groups that aren’t closely related Thecosomata are the shelled organisms called “sea butterflies” Gymnosomata have no shell and they are called “sea angels” The sea angels are predators on the sea butterflies and suck them right out of their shells

Question 39

sea gooseberries

Answer 39

Ctenophores

Question 40

Sea Butterflies

Answer 40

Mollusca (pteropod)

Question 41

Velella

Answer 41

cnidarian --> hydrozoan

Question 42

Nomura jellyfish

Answer 42

cnidarian --> scyphozan

Question 43

Platynereis dumerilii

Answer 43

Trochophore larvae vertically migrate. ``` Swim up to surface at Night & down in day Larvae produce melatonin only at night. Melatonin causes the neurons that control beating Hairs to stop beating, and the Larvae sink at end of the daylight. Precursor to sleep? ```

Question 44

Oceanographic “Fronts”

Answer 44

areas where two water masses meet Zooplankton typically have high populations in these frontal regions. Recent research in the Red Sea (Genin et al. 2005, Science 308, 860) shows that zooplankton are able to aggregate into “patches” and hold their depth by swimming against these vertical currents.

Question 45

how are zooplankton distributed? (even if the environment is homogenous)

Answer 45

NOT homogeneously -- patch or clumped

Question 46

what causes patchiness?

Answer 46

``` Langmuir circulation cells Fronts Grazing by groups of predators their food is patchy too ext ```

Question 47

Calanus pacificus

Answer 47

copepod-- Spends the winter deep as Stage V copepodite In Jan-March it molts to adult stage and goes to surface where phytoplankton are blooming. In summer eggs hatch In autumn Stage V migrates down to spend winter where it is cool Thus its life cycle is tuned to be able to be ready to feed as adults on the spring phytoplankton bloom

Question 48

Calanus (copepod) fecal pellets

Answer 48

Adult females of C. finmarchicus feeding on diatom cultures produce a fecal pellet every 5-7 minutes. Size is ca 0.2-0.6 mm. Pellets this size sink a few hundred m/day Those from Euphausids sink 100-800m/d Nutritional value can vary Bacteria colonize pellets rapidly At 22oC 16% of C lost by bacterial decomposition in 1 d, 67% in 2 d At 5oC loss was only 10% in 14 d, so if a pellet makes it into deep water fast enough its energy will make it to the bottom for benthic organisms to feed on

Question 49

Microzooplankton-

Answer 49

Microzooplankton- Ciliates-cilia Flagellates- 1 to many flagella Amoeba-pseudopodia (rhizopods)

Question 50

Mesodinium

Answer 50

“red tide” From Cryptomonad pigments (are a group of algae, most of which have plastids)) Phycoerythrin (any of a group of red photosynthetic pigments )

Question 51

Amoeboid Forms (Phylum Sarcodina)

Answer 51

Amoebae-usually attached to surfaces but a few are planktonic. Can cause diseases in lobster & crabs Testaceans- Amoeba lives in a shell or “test” Most are freshwater Foraminifera -Have a multi chambered shell. Put out long (15 mm) streamers called rhizopods Heliozoa-Freshwater “sun animalcules” Radiolaria- siliceous spines Acantharia- 20 strontium sulfate spicules

Question 52

Testaceans

Answer 52

Amoeba lives in a test or shell. Most are freshwater.

Question 53

Foraminifera

Answer 53

benthic & planktonic amoeboid species. There are different shell types. (Sarcodina) Have a multi chambered shell. Put out long (15 mm) streamers called rhizopods

Question 54

more about foraminifera

Answer 54

Foram shell (test) can be gelatinous, chitinous, calcareous or siliceous-shape varies a lot. Chambers connected by pores going from oldest to newest Ca 40 planktonic & 4000 benthic species Have photosynthetic symbionts in test Rhizopodia used in feeding Paleontology-Water temp. affects distribution of a species and shape of the test. Larger tests from colder waters. Studies on species in sediments give clues to past climates. Planktonic Forams very abundant between 40N & 40S

Question 55

Radiolaria-

Answer 55

have a central membrane separating granular endoplasm from frothy ectoplasm Skeleton is of silica. siliceous spines

Question 56

Chaetognaths

Answer 56

(Arrow worms). Abundant carnivorous group. Most < 4 cm long

Question 57

Copepod feeding is complex and feeding currents are established...

Answer 57

by the maxillae they make feeding currents with antenna, setae catch food particles, feeding limbs creat the vortices (circle movement) around the body

Question 58

Copepod feeding (explained in human context)

Answer 58

Feeding is like trying to eat while suspended in molasses. Pretend you are in molasses and you want to grab a donut suspended in front of you. If you reach for food particle it is pushed away from you (a) and if you try to clasp it (b) it squirts away. You can try a zig zag (c) back and forth to grab it. This can work. Basically (d) put your elbows against your waist and fling your arms open to draw in the donut, then open your elbows and this will pull the donut closer & next close your arms in then close your elbows in again.

Question 59

Copepod feeding (explained in human context)

Answer 59

Feeding is like trying to eat while suspended in molasses. Pretend you are in molasses and you want to grab a donut suspended in front of you. If you reach for food particle it is pushed away from you (a) and if you try to clasp it (b) it squirts away. You can try a zig zag (c) back and forth to grab it. This can work. Basically (d) put your elbows against your waist and fling your arms open to draw in the donut, then open your elbows and this will pull the donut closer & next close your arms in then close your elbows in again.

Question 60

what is the microbial loop?

Answer 60

Bacteria are then eaten by microzooplankton. Some microzooplankton are eaten by larger zooplankton but most release more DOM which is taken up by bacteria forming a loop