Physiology of Finfish and Shellfish (2+1)

4.1.2. Nutrition and metabolism in fish

Nutrition is the process of nourishing the individual cells of the body N- to a layman -> just requirements of nutrients of flour supply. But to a physiologist N response includes process of feeding, digestion and astemilation.

Prodn of energy from assimilation nutrients – dealt under metabolism.

Feeding – is the aqusition and ingestion of food.

Digestion is the break down of complex consumed food into simple assimilabel forms. The ingested food of any origin cannot be taken as such to cells for energy production – need by cells. In higher animals all cells cannot take up – directly from dig. syst.

Therefore – dig. syst → blood → tissues.

So N is the movement of cells i.e. supply of food.

Why food needed? → for 2 purpose → production of heat – for muscular movement

→ Chemical synthesis – for growth reproduction.

Thus energy as needed for -

Providing fuel for keeping alive and maintaining body processes

Providing raw material for gr and reproduction.

Produced energy → prot. syn. → DNA → reproduction – nut cells.

New cells → if added to body → growth

→ If added to off spring or gamete → reproduction

Source of energy?

All animals – receive energy as chemicals – from planits either directly or throorhter animals/org. plants from in so sum is the ultimate source.

If any form of life on earth – dependent on sure

But, secretly found a community of orgms on sea ocean boltom – geothermal water – Sulphur – reducing bact (chemicals) – others of worm, fish etc.

Feeding strategy in fish:

Fishes are the dorminating vertebrate group as far as number of speclex is concerned and in their immense variety have adopted many nutritional habits.

They are: planktivores (phyto and zoo plan), herbivores (large plant feeders), insectivores larvivores, piscivores, detritivores, parnasites etc. cyclostimic (lamprey and hag fishes) catch or such fold habit involved special feeding strategy. It is different for each sp/group.

e.g. Hantitivores – filter feeding – from flowing water – served.

Herbivores – foraging – cutting, scrapping, browsing etc.

Insection, larvi, pisci and other predaceous – chasing behavior and capturing.

Parasites – injuring and sucking.

Each of such feeding strategy has structural adaptations.

e.g. parasites (cyclo-) – have jawless suctorial mouth with horning teeth. During attachment to host – water flew – independent of mouth created for espiration.

In gnathostomes – anterial visural arches form jaws – which are simple in else chondrichthyes teeth.

In ostechthyes – jaws are complex with arrangements of muscles, nerves, ligaments, etc.

Such jaws are used in respiration, biting, scrapping, chewing, discarding of unwanted etc.

Other structural adaptation for feeding are positioning of fins, protrucibity of mouth, changes in jaw and snout shape (e.g. the elongation – easy snipping on of coral polyps; changes in tooth shape (incisors, crushing teeth, fused plates), development of accessory feeding structures like barbels, behavioral changes (coris rolls over stones or)