Feeding 3: Maximizing Feeding through Plasticity

Feeding 3: Maximizing Feeding through Plasticity

1. Morphological Plasticity

   • Adaption of feeding structures
     • Leg Plasticity
       • Marchinko (2007) Looked at leg plasticity in Balanus glandula
         • Found clear difference in plasticity of animals in exposed compared to sheltered
           • Exposed shore animals had shorter, fatter legs
           • Sheltered organisms had long, thin legs
         • Number of Cirral beats also seemed to increase within exposed organisms - ADAPTIVE
         • In sheltered shore organisms, cirri became deformed and were not used effectively
           • Developed testing behaviour, to see if okay to feed
       • An organisms ability to change leg plasticity to suit env. conditions. e.g. shore exposure
     • Velum plasticity
       • Strathman et al. (1993) exposed veliges of Crassostrea gigas to high and low food rations over time
         • The more scarce the food source, the greater allocation to feeding structure development
           • in low food areas, the size of the velum was found to increase in size
           • The length of the cirri was also found to increase
             • Potentially better at food collection
               • Cilial Allometry - increase length can increas max clearance rat
     • Stomach plasticity
       • Miner (2005) investigated how high food rations affected stomach size in S.pupuratus
         • At low food levels, stomach size was found to decrease
         • Sea urchin species

2. Behavioural Plasticity

   • The adaption of feeding behaviours, in order to fit specific diets
   • Cruz-Rivera & Hay (2000) investigated animals affinity for low/high quality feeds
     • Looked at mobile and sedentary stages of amphipods,
     • Fed them diets consisting of either 1) algae or 2) Fish food
       • First trials animals were selective as chose the higher quality feed source (fish food)
     • Amphipods were also fed on only a low quality diet to see if they could compensate
       • All species of amphipod were shown to compensate
         • Amphipods did suffer a trade off with nutritional quality over quantity
           • With effects leading to reduced Survivorship, growth and fecundity
   • Pochelon et al (2009) Pre-exposed Nephrops norvegicus larvae to either starving or high levels of food.
     • This created pre-exposed phenotypes
       • They then re-exposed the lobsters to high and low levels of food
         • ORganisms adjusted food intake in relation to what thehy had been pre-exposed to
     • Organisms were also fed different types of prey to look at ontogenetic plasticity
       • Found that N.norvegicus preferred smaller prey to what had been previously fed

3. Digestive Enzymes

   • Le vay et al (2001) investigated ability to alter enzyme amount in Shrimps.
     • fed the shrimps either algae (high trypsin) or artemia (low trypsin)
       • Was found that organisms were able to alter amount of digestive enzymes depending on the feed being fed.
         • Producing less Trypsin when being fed a high quality diet.
           • Suggests diet-specific plasticity
   • organisms altering amount of digestve enzymes used to breakdown feeds

4. Life History

   • Organisms altering their feeding strategy through different life stages
   • Anger & Hayd (2009) looked at feeding ontogeny in Amazon River Prawn from non feeding (lecithotrophy) to feeding (planktotrophy)
     • Eggs are laid in freshwater conditions with low food availability
       • Cope with this through heavy reliance on maternal provisioning - using lipid droplets to feed
     • Is a point at which the shrimp become obligatory planktotrophic
       • but there is a stage where plasticity occurs and they can survive being lecithotrophic