Feeding

Question 1

feeding definition

Answer 1

gathering and ingesting food

Question 2

digestion

Answer 2

breakdown and transferring required nutrients into the body

Question 3

Ways of obtaining nutrients

Answer 3

 Autotrophic – including plants algae and some bacteria – able to produce their own food and energy
 Heterotrophic – consumers – all animals must obtain nutrients from other plants or animals for energy and nutrients

Question 4

Short food chains vs long

Answer 4

Short food chains deplete less energy prior to consumption thus more efficient than long food trains

Question 5

Why did animals evolve within the sea

Answer 5

The ocean was a source of more of a more constant environment, so they didn’t have to evolve ways of dealing with so many different environmental factors

Question 6

earliest metazoan marine life

Answer 6

Ediacaria period - 550myr ago

Question 7

Feeding behaviours within ediacara period

Answer 7

detrivores and carnivores were able to capture protists and bacteria
* Primary productivity was and still is limited to the surface areas of the ocean
* Benthic organisms were and are dependent on organic detritus falling from the surface of the ocean

Question 8

Exceptions of benthic organisms feeding on detritus

Answer 8

hydrothermal vents and cold seep ecosystems

Question 9

Feeding methods

Answer 9

Small particle feeding
Large particle feeding
Fluid feeding

Question 10

Small particle feeding

Answer 10

suspension or filter feeding – consume material suspended in water column
* Specialized flagellated cells – choanocytes – move flagella to draw in water through pores
* No gut – direct cellular ingestion of captured food

Question 11

Filter feeding – mucociliary

Answer 11

• External mucociliary mechanisms – use motile cilia and mucus to capture food particles of the appropriate size
  1. Create a current of water bearing particles
  2. Separation of particles from the water
  3. Transfer of particles to mouth
  4. Ingestion occurs

Question 12

Filter Feeding - Amphiuridae

Answer 12

• Feed by holding their arms into the water column and trapping particles in flowing water
• Particles are moved to the mouth using groove on their oral side
• In stagnant water they switch to deposit feeding

Question 13

Deposit feeding

Answer 13

ingestion of living and non-living organic matter (crabs)

Question 14

Setae

Answer 14

external setae or cirri = long closely spaced feeding setae on numerous appendages used to collect food

Question 15

Baleen whales

Answer 15

– two sets of baleen plates – (keratin) sieve food particles from the water

Question 16

Basking sharks

Answer 16

can strain 2000 L of water per hour swim with mouth continuously open to feed on the zooplankton – gill rakers trap and filter out plankton – mouth closes to swallow

Question 17

Deposit feeders

Answer 17

• Consume large amounts of organic matter within sediments
• Vital for the regeneration of nutrients and enhance benthic productivity
• Eg. Ragworm

Question 18

Radula adaption

Answer 18

found in many gastropods – used for scraping algae off rocks – can be found in carnivorous snails to rasp flesh off dead animals
- Structure = many sets of small teeth in which move back and forth to scrape off algae the structure is then pulled back into the buccal cavity to ingest the particles

Question 19

Aristotles lantern

Answer 19

• Sea urchins possess a very intricate mouth apparatus – Aristotles lantern which is comprsed of a powerful set of jaws – makes them a very successful herbivore

Question 20

Hunting behaviour

Answer 20

some species feed by targeting and subduing individual food items, but others will work together in teams and in pods to chase the prey that they are after

Question 21

Orcas

Answer 21

• Eat fish, squid, sea otters, and seals by attacking them with sharp teeth.
• Behavioural specialists depending on prey
• Hunt in packs (e.g., pods of five) for higher success rates.
• Prey is divided among the group after catching it.

Question 22

Dolphins

Answer 22

• Hunt in pods.
• They corral bait balls by swimming around them to bunch up the fish.
• Dolphins slap the bait ball with their tails to stun the fish - float to the surface, making them easier to catch.
• Dolphins also use a technique called mud nets to trap fish

Question 23

Specialised radula

Answer 23

• drill snails- that cuts a hole through shells – either sucks out living tissue OR injects venom to paralyze

Question 24

Nematocyctes

Answer 24

• Exclusively found in the phylum Cnidaria
• Coiled, hollow, barbed thread that quickly turns outward
• Often contains poison
• Prey capture and defence

Question 25

Photosynthetic symbiosis

Answer 25

endosymbiotic algae produce nutrients through photosynthesis – passed on to corals cells  Coral emit waste produce (NH4 etc) consumed by endosymbiotic algae

Question 26

Chemosynthetic symbiosis

Answer 26

(hydrothermal vent worms) -They have a symbiotic relationship with chemoautotrophic bacteria and lack a mouth, gut, or anus.  Food comes from sulfur-oxidizing chemoautotrophic bacteria within a trophosome.  Require hydrogen sulfide, found near hydrothermal vents.  Sulfate is produced in the trophosome and voided across the gills.  Bacteria produce energy and transfer it to the worm.

Question 27

Intracellular digestion

Answer 27

* Gastrovascular cavity - has one opening and a blind tube or cavity that serves as mouth and anus * Digestive enzyme in tubular cavity break down food and food particles are engulfed by cell lining within the gastrovascular cavity

Question 28

Extracellular digestion

Answer 28

* Alimentary canal – digestive tract with a mouth at one end and anus at the other end * Food is ingested in through the mouth passes through the esophagus and stored in the crop

Question 29

Evolution of the through gut

Answer 29

* Allowed for continuous food processing * Increased ability to process bulky and low quality foods * Multiple mechanical and chemical processes along length of gut such as changing pH to optimise enzyme activity

Question 30

Gut structure

Answer 30

* Foregut * Midgut * Hindgut

Question 31

Foregut

Answer 31

ectodermal in origin = ingestion and mechanical breakdown of food * Buccal cavity – saliva to lubricate passage of food and enzymes to start digestion * Pharynx – pump food down to gut – aid mechanical breakdown and mixing of food * Esophagus/crop – either carries food directly to stomach (crop is associated w animals that have large infrequent meals)

Question 32

Midgut

Answer 32

– endodermal in origin = nutrient absorption * Muscular stomach – starts or continues the comminution of food = sometimes mechanical breakdown * Secretory caeca – branch off immediately after stomach = production of digestive enzymes and absorption of digested food * Intestine – intracellular digestion in lower invertebrates = extracellular digestion in animals processing large masses of food

Question 33

Hindgut

Answer 33

– ectodermal in origin = elimination of waste through anus * Rectum – selective reabsorption of water and salts from food - Site of faecal pellet formation - highly distinctive shapes can be used to identify species presence

Question 34

Types of meal processing – reactor models

Answer 34

- Batch reactor - continuous flow reactor with mixing - continuous flow reactor without mixing

Question 35

* Batch reactor

Answer 35

– each meal is processed before the next meal enters

Question 36

* Continuous flow reactor without mixing

Answer 36

meals line up so they don’t mix but each meal processed for longer than batch reactor

Question 37

* Continuous flow reactor with mixing

Answer 37

– new meals mix with meals that have already undergone some processing

Question 38

Secondary loss of the through gut

Answer 38

* 25% of 30,00 fish spp have lost ability to use stomachs because of a change in diet - no need for stomach enzymes * Lost gene for gastric proton pump and for pepsinogens * food is passed into the stomach in a cord of mucus * Stomach acids reduce viscosity of mucus and particles are released * Remaining gut is alkaline – restores viscosity of the mucus and production of faecal pellets occur

Question 39

Chordates

Answer 39

mucus chord moved to stomach by cilia of the pharyngeal basket and esophagus

Question 40

Bivalve digestive strategies

Answer 40

* 2-phase digestive system: rapid intestinal pathway OR slower, glandular pathway * Evolved this digestion strategy to avoid excess assimilation of metals * Reduced ingestion rates under high Cr * Reduced proportion processed by glandular digestion under high Cr * Able to modify processing to reduce exposure to Cr

Question 41

Gut microbes – herbivorous fish

Answer 41

* Different algae types have unique compositions of polysaccharides. * Herbivorous fish use specific enzymes to break down these large polysaccharides to obtain energy from algae.