Feeding & Digestion

Question 1

What are the only life forms to have evolved on land?

Answer 1

Uniramia/insects

Question 2

What is the only organism not fuelled by solar energy/photosynthesis?

Answer 2

Those that rely of deep sea vents or cold seeps (chemoautotrophs)

Question 3

What are the 3 types of feeding?

Answer 3

Small particle feeding (in suspension or already breaking down (detritivory)), large particle feeding (large amounts of low-grade) and fluid feeding

Question 4

What is fluid feeding?

Answer 4

the direct uptake of dead organic matter (DOM) by the piercing of another organism

Question 5

How do porifera feed?

Answer 5

suspension feeding using choanocytes - nutrients transferred via intracellular transfer.

Question 6

What is external mucociliary food capture?

Answer 6

suspension feeding using external organ

Question 7

How do polychaetes feed?

Answer 7

external mucociliary capture using branched, ciliated tenticles which capture particles from near-bottom currents

Question 8

How do bryozoa and bivalves feed?

Answer 8

external mucociliary capture using modified gills with ciliation to generate water flow for gaseous exchange as well as particle capture

Question 9

How do brachiopods feed?

Answer 9

external mucociliary capture using a modified lophophore

Question 10

How do echinoderms feed?

Answer 10

external mucociliary capture with long, thin arms

Question 11

How do holothurians feed?

Answer 11

External mucociliary capture using branched, ciliated, filamentous tentacles with mucus-producing glandular cells

Question 12

What are the 3 forms of suspension feeding?

Answer 12

external mucociliary particle capture, external setose particle capture and non-ciliate mucus particle capture

Question 13

Give 2 example organisms that use non-ciliated mucus particle capture

Answer 13

tube-dwelling polychaetes and gastropods

Question 14

how do tube-dwelling polychaetes feed?

Answer 14

non-ciliated mucus particle capture by generating an opposing mucus-water counterflow.

Question 15

How do gastropods feed?

Answer 15

non-ciliated mucus particle capture with mucus threads which spread out over surface and collect particles before being drawn back to the mouth

Question 16

How do urochordates (tunicates) feed?

Answer 16

non-ciliated mucus particle capture using a fan

Question 17

how do some polychaetes use non-ciliated mucus capture?

Answer 17

by forming temporary burrows and spread out a mucus lining within burrow. Movement of body draws water over mucus, allowing for particle capture.

Question 18

Name 3 organisms which use deposit feeding?

Answer 18

echiurans (spoon worms), bivalves and holothurians

Question 19

How do echiurans (spoon worms) feed?

Answer 19

deposit feeding using proboscis extension moving over sediment with cilia.

Question 20

How do burrowing bivalves feed?

Answer 20

deposit feeding using long, highly flexible siphon which reaches the sediment surface and acts as a vaccum

Question 21

how to echinoderms feed?

Answer 21

deposit feeding with a crown of tentacles spread out over sediment, ciliated with mucus to pick up particles. Mucus streams occasionally withdrawn using muscular action to the mouth.

Question 22

Name an organism that uses external setose particle capture

Answer 22

Crustaceans, e.g. barnacles, have limbs with hair-like setae acting like sieves (limbs occasionally drawn through the mouth for feeding)

Question 23

How do sipunculans feed?

Answer 23

deposit feeding using introvert with terminal mouth

Question 24

What is a nepheloid layer?

Answer 24

the sediment-water interface - area of strong near-bottom current

Question 25

Name 2 sediment interceptors

Answer 25

gorgonian cnidarians and crinoid echinoderms

Question 26

How may bivalves act as predators?

Answer 26

they have hook-like structures developed from their foot used to scoop up jellies and crustacea

Question 27

How may gastropods act as predators?

Answer 27

with spiked oral hoods to capture gelatinous organisms or small fish

Question 28

What is a rynchocoel?

Answer 28

an internal cavity in a nemertea that hold the proboscus

Question 29

Which organisms use fluid feeding?

Answer 29

Nematodes and most meiofauna

Question 30

What are the two types of symbionts and how do they differ?

Answer 30

Photosynthetic symbionts (using chloroplasts of other organisms) and thiobiotic symbionts (using hydrogen sulphates generated by other organisms near hydrothermal vents)

Question 31

Name a key difference in the digestive system of a platyhelminth and a nemertean?

Answer 31

platyhelminths have a blind-ended gut as opposed to a through-gut, which only allows for episodic feeding.

Question 32

What are the key characteristics of a predator's gut?

Answer 32

Predator guts are generally shorter with stronger proteolytic enzymes in a highly acidic stomach (to allow for faster digestion)

Question 33

What are the 3 sections of the gut?

Answer 33

The foregut (chemical), mid-gut (mechanical), and hind-gut (chemical)

Question 34

How can the 3 sections of the gut be defined embryonically?

Answer 34

the foregut and hindgut both have an ectoderm from their formation from blastula indents

Question 35

What does the fore-gut consist of and what happens there?

Answer 35

mouth, where glands may produce saliva, toxins, and/or anticoagulants, the pharynx and oesophagus where mechanical and chemical breakdown continues

Question 36

What does the mid-gut consist of and what happens there?

Answer 36

a muscular stomach containing acid for breakdown of food (may also include a gizzard for intense mechanical activity), a small (may include hepatopancreas/liver) and large intestine.

Question 37

What caused the secondary loss of the through gut?

Answer 37

animals requiring minimal digestion and little/no excretion

Question 38

Describe the process food goes through from suspension feeding?

Answer 38

mucus passes into gut, where it undergoes a lower pH, causing a change in nature of mucus from stringy to liquid, releasing food particles into the stomach. After returning to an alkaline environment in the intestine, mucus facilitates the formation of faecal pellets

Question 39

How to lophophorates and molluscs draw in food without using mucociliary action?

Answer 39

they use a continous rope of mucus winched in by a rod of faecal material. In molluscs, a rod of hyaline protein forms a crystalline style to grind food and also contains digestive enzymes

Question 40

How is wood boring ecologically important?

Answer 40

it contributed to the flow of carbon through a marine ecosystem

Question 41

Name 2 organisms that have adaptations for the breakdown of difficult material

Answer 41

Limnoria and Teredo

Question 42

what are cestodes?

Answer 42

parasites that live in the gut of their host, so that all digestion is done by the host.