Invertebrate Feeding
- Created by: daisygbates
- Created on: 21-05-17 16:42
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Invert Feeding
Microphagy
- Feeding off of tiny food particles
- Probably favoured by ancestral inverts
- Disadvantges
- Food widely dispersed, so animal must be mobile
- Constrained by body size
- Evolution favoured a larger body size, so..
Macrophagy
- Advantages of large body size
- Increased reproductive output
- Reduced mortality
- Competitive advantage
- Can be classified according to diet and behavious
- Herbivory
- Predatory
- Easiest form: suspension feeding
- 2 types
- Passive (Interceptors)
- Consume organic matter whilst suspended in water column
- Mucus covers spines, trapping suspended particles
- Wiped off by a tube foot, transferred to scale and passed to mouth
- Active
- Common
- Requires a filter to capture suspended particles
- Current expelling water is more powerful, often coupled to removal of waste products
- Cilia generate current
- Flow = unidirectional
- An array of feeding appendages
- Polychaetes have tentacles
- Bryozoa have lophophore
- Bivalve molluscs - ctendial gills
- Some use mucus to trap particles
- Mucus secreted as a bad/threads through which a current is generated
- Mucus is then consumed along with trapped particles
- EXAMPLE - Chaetopterus sp.
- Often couples as a respiratory surface
- Arthropods
- Do not possess cilia, so use setae on specialised appendages
- Copepods use maxillipeds
- Barnacles use their legs
- Some crab species use antennae
- Setae - bristles used to trap suspended particles
- Do not possess cilia, so use setae on specialised appendages
- Passive (Interceptors)
- 2 types
Deposit Feeding
- Some inverts consume surface material
- Don't need specialised feeding structures
- Disadvantages
- Little available organic matter
- Limited by bacterial productivity
- Important in the deep sea
Herbivory
- Requires robust mouthparts
- Echinodermata, Echinoidea: Aristotle's Lantern
- 5 pyramids supporting the teeth
- Under muscular control
- Rasping and chewing
- Mollusca eg. radula and jaws
- Chitinous teeth
- Scraping/rasping action
- Buccal cavity
- Arthropoda eg. insects
- Do not typiccally suffer food shortages
- Disadvantges
- Chemical defence mechanisms
- Large proportion of diet is indigestible
- Often have bacteria within gut to asist in breakdown of plant material during digestion
- Echinoderms also have N2 fixing bacteria
- Molluscs have evolved enzymes (cellulases) to break down plant material
- Some avoid indigestible plant material by sucking sap
- Requires complex mouth appendages
- Poor diet, lacks protein
- Utilises symbiotic bactera
- EXAMPLE…
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