Feeding Mechanisms

Question 1

Suspension feeding principles

Answer 1

Concentration and separation of suspended particles from the surrounding seawater
- creation of a feeding current
- trapping of particles on a filter or membrane
- removal of particles from filtering apparatus to mouth
Detection and selection process to reject some particles

Question 2

Filter feeding Principles

Answer 2

Three types of aparatus
- Mucous mesh (gelatinous plankton)
- setae (crustaceans)
- cilia (echinoderms)
detection and selection processes

Question 3

Mucous mesh techniques

Answer 3

Muscular pumping:
- apendicularian and salps
Muco-cillary:
- Doliolid
Sedimentation:
Theocosome

Question 4

Thecosome pteropods feeding

Answer 4

Parapodia wings produce mucous web in <5s
Hang motionless and trap phyto and small motile prey
Animal consumes entire mucous structure and attached particles

Question 5

Appendicularians feeding

Answer 5

Inlet filters exclude large prey
Food Concentrating filter
Particle charge and shape determines what is ingested
Explicit spout through which rejected particles are expelled.

Question 6

Salps feeding

Answer 6

Pump water into oral siphon, through pharyngeal chamber and out atrial siphon
Pumping action generated by muscles, creates jet propulsion for movement.
Food particles entering chamber strained through mesh, which is secreted by endosyte.
Rolled into food strand and moves to oesophagus

Question 7

Copepod detecting prey

Answer 7

Motion, viscous and sensory cues
Motion core, water always passing through
Viscous core, feeding current
Sensory core, detection area
capture area, copepod mouth
Chemosensory sensillae and mechanosensory setae

Question 8

Mechanoreception

Answer 8

Copepods perceive presence, shape, orientation of particle 100s microns to mm from body
Detection by P receptors in 1st antennae and body to identify disturbance
Particles detected in sensory layer surrounding viscous core, copepod capture by reorientation
Some particles detected and drawn through viscous core, without capture and rejected.

Question 9

Chemoreception copepods

Answer 9

Used to detect food quality (C:N, chl a per cell) in the solute cloud surrounding algal cells

Question 10

Behavioural changes copepod

Answer 10

Positional change of body produces active redirection of feeding stream into capture area

Question 11

Prey characteristics which influence detection

Answer 11

Presence of toxins
Presence of other organic compounds
C:N and chl a content per cell
Swimming motion
Swimming speed
Distance from prey

Question 12

Copepod mouthparts

Answer 12

Trophic segregation
- different copepods eat different: algae, protozoans, nauplii
- morphology of mouthparts differ with diet

Question 13

Copepod setae and size selection

Answer 13

Size dependent particle selection is based on the inter-setae and inter-setule distances (spaces)

Question 14

Ontogenetic trophic niche separation

Answer 14

Ontogenetic body size, between copepodite and adult stages, produce filter which traps particles of differing size and species
Absolute size of particles and spectrum of particles increases with size

Question 15

Interspecies trophic niche separation

Answer 15

Copepod species can differ in size 10-20%
Resulting differences in filter size and inter-setae and inter-setule spaces are sufficient to establish in separate feeding niches
Trophic co-existence of several species can occur

Question 16

Mixed diets in copepods

Answer 16

Growth rates of females on mixed diets is significantly higher
Nauplii growth impaired and mortality with some single diets.

Question 17

Taxa with cilia

Answer 17

Molluscs
Polychaetes
Echinoderms

Question 18

Predator feeding mechanisms

Answer 18

Cruise feeding
ambush

Question 19

Methods of detection of prey

Answer 19

Mechanical
tactile
chemical
visual

Question 20

Capture methods of prey

Answer 20

Entangling with tentacles
raptorial with mouth

Question 21

Copepod diet

Answer 21

Can switch trophic mode according to relative abundance of prey
Variety of prey across taxa and size
Specific feeding methods among different prey species based on the traits of prey
Graze on ciliates and dinos when diverse foods offered, nutrional
Discriminate between individuals of same species with same properties

Question 22

Copepod foraging

Answer 22

Swim, search and capture depends on diet

Question 23

Copepod prey switching

Answer 23

Acartia tonsa has 2 different modes of feeding:
- Immotile prey, generate feeding current, capture cell arriving.
- motile prey, sinks through water and ambushes

Question 24

Chaetognaths

Answer 24

Ambush raptorial
Large head, grasping spines, anterior and posterior teeth.
Complex nervous S, vibration sensors and eyes
Transparent
Strong swimmers
Cruising ambush and ambush predators
Regular and short bursts of swimming followed by passive sinking
Eat copepods

Question 25

Fish larvae

Answer 25

Visual raptorial yolk sac feeds larvae. first feeders <5mm, weak swimmers large larvae are stronger sight prey at <1 body length Bend body into S and dart forward

Question 26

Search factors

Answer 26

Volume search depends on: - sighting distance - FOV - searching speed

Question 27

Prey capture factors

Answer 27

Ability depends on: - jaw gape - age (Size) - hydrodynamics

Question 28

Ambush entangling

Answer 28

Tentaculate ctenophores, siphonophoresd, coronate jellies Stationary in water and wait Some swim in water and sink with outstretched tentacles Large SA with long tentacles

Question 29

Cruising entangling

Answer 29

Aurelia, cyanae medusae swim, create current, slower swim prey into bell

Question 30

Biomechanics of jelly bell

Answer 30

Prolate (arched) swim by jet propulsion Oblate (flat) rowing propulsion Muscular contractile forcesd required to achieve jet propulsion do not scale with increasing medusa size Small bell diameter, enough muscle to expel water from bell for jet Large, not enough muscle

Question 31

Prolate jelly behaviour

Answer 31

Ambush foraging Primarily impact highly motile prey

Question 32

Oblate jelly behaviour

Answer 32

Cruising pred Prey encounter depends on motions generated by pred relative to prey Selection depends on vulnerability of prey to entrainment and prey size when encountering capture surfaces

Question 33

Medusae feeding

Answer 33

Once detected prey, changes swimming pattern to more vertical, increases encounters Chemosensory detection, simple kinesis rather than tactic response

Question 34

Prey capture in medusae

Answer 34

Cnidocytes contain cnidocysts - nematocyst, spirocyst, ptyocyst Once inside ball, medusae use tentacles, mucous and cilia to transfer prey to mouth Mucous on bell and tentacles to trap

Question 35

Ctenophores prey capture

Answer 35

Capture fast swimming prey using tentacles with colloblasts on Tentacles rapidly contract Body spins round and tentacles move food to mouth

Question 36

Raptorial feeding in Beroe sp

Answer 36

Class nuda without tentacles Eat only other ctenophores, swallow whole

Question 37

Why are jellies effective

Answer 37

large body size, low C, high water Type I feeding functional response, linear response to increasing food conc Cosmopolitan diet, Most taxa